Novel Polymer Shelves (See Projects Section on Linkedin)

PolymerWorks
Team: Mick Blackwell, Ben Condro, Mark Dufresne, Brenton Lester, and Matt Lewis
Advisor: Dr. Gipson and Dr. Prins
Topic: Materials and Mechanics Project (SUDoKU Portfolio)

Non‐Traditional Polymer‐based Shelving Units
Shelf Unit Conceptual Portfolio (SUCP)
March 30, 2014
Mechanics and Materials Semester Project
Team: PolymerWorks
Students: Mick Blackwell, Ben Condro, Mark Dufresne, Brenton Lester, and Matt Lewis
Advisors: Dr. Kyle Gipson and Dr. Robert Prins

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Table of Contents
I. INTRODUCTION………………………………………………………………………3
II. LITERATURE REVIEW………………………………………………………………3
III. PURPOSE AND OBJECTIVES………………………………………………………4
IV. MATERIAL SELECTION ANALYSIS…………………………………………….. 5
V. DESCRIPTION OF SHELVING UNITS…………………………………………….12
VI. MECHANICAL ANALYSIS………………………….……………………………..15
VII. SYNTHESIS OF ANALYSIS INTO DESIGN……………………………………..28
VIII. CONCLUSIONS AND RECCOMENDATIONS………………………………….30
IX. REFERENCES……..……………………………………………………………….. 30
X. APPENDIXES……………………………………………………………………..….32

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Introduction
In order to properly design a product, mathematical analysis and analytical modeling for each
component are necessary to obtain parameters and confirm feasibility of proposed designs. The
following sections document four designs correlated to obtained customer needs in order design
of a novel shelving system.
Each design was modeled analytically using SolidWorks and mathematically analyzed using
known mechanical methods. The mechanical analysis, ecological audits, and tabulated material
properties were compared in order to choose the most appropriate material and design for
fabrication of the product.
Literature Review
Research was conducted on common polymer-based product manufacturing methods due to
project constraints requiring a polymer shelving unit, as well as known polymer benefits and
disbenefits at large. An overview of the applicable research conducted will be explained and
further information can be found in the references used.
Polymers can be found in any department store or building around the globe. For instance,
electrical outlets have a plastic face constructed from an electrically resistant polymer [8]. There
are many methods of producing polymer products: thermoforming, extrusion, injection molding,
blow molding, compression molding, plastic machining, and transfer molding [10]. However,
some polymers are not feasible alternatives for select manufacturing processes. For example,
polycarbonate is not normally shaped using the thermoforming process [10].
Moreover, blow molding is commonly used to produce thin walled products such as plastic bottles.
Compression molding can only be used for a small subset of polymers and makes familiar items
such as the previously mentioned wall outlet. Transfer molding is commonly used for molding of
thermal sets, thus can only be used for a few select polymers [10].
For a shelving unit, a select set of polymers were chosen based off of needs discussed further in
the document. Mentioned needs were established from surveys conducted within the target market.
The surveys and results, in entirety, can be found in Appendix A3. As such, potential materials
which passed screening were polycarbonate, high density polyethylene, and polypropylene.
Materials such as polycarbonate and polypropylene are commonly molded using the process of
injection molding. According to the Polymer Molding Handbook, “After over a century of world-
wide production of all kinds of injection-molded products…the products can be processed
successfully, yielding high quality, consistency, and profitability” [9].
Furthermore, note that different subsets of polymers will behave differently when molded by
injection. For instance, polycarbonate (PC), if injection molded, would require special ventilation
during cooling, since PC is hydroscopic material [9]. Therefore, designers must tradeoff between
the only two viable methods remaining for a shelving unit: plastic machining and injection
molding. Aspec Plastics states, “Molding theory states that you can purchase an expensive mold

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and produce inexpensive parts, or you can purchase an inexpensive mold and produce expensive
parts” [11].
The general rule of thumb is as follows; when producing large amounts of products (100,000+)
and low tolerances are acceptable, injection molding is considered the most cost efficient method
[12]. Project constraints stated that the shelving unit would be produced in quantities larger than
100,000. Conversely, injection molding is heavy reliant on electricity for producing components.
Approximately 90% of electricity consumed is used to operate the powerful machinery [13]. To
better disperse the energy consumption into the actual components, multi-cavity molds should be
utilized to increase component output per cycle [14, 15 (In particular, reference 15 offers many
cost saving training videos correlated to injection molding)].
In conclusion, based off of conducted research and known product constraints, injection molding
was the most feasible alternative for shelf production. A more detailed analysis of the project
requirements and analysis is stated in the following sections.
Purpose and Objectives
The purpose of this project was to use the best aspects of a type of material to create a feasible and
innovated shelving unit. The shelving unit should adhere to the four pillars of sustainability:
technological, environmental, economic, and social. By using mechanical analysis, ecological
audits, and found material properties, a designer can sufficiently validate the design decisions
made during the process.
The home market, described in the design restrictions, included college-aged 20-somethings.
Furthermore, the material used for the fabrication of the shelving unit must consist mostly or
entirely of plastics from the polymer class of materials.
Objectives for the design process include the goals listed below:
 Satisfy all customer needs while balancing the four pillars of sustainability.
 Design a shelving unit most suited for the injection molding process (See the Literature
Review section for the reasoning behind choosing injection molding).
 Minimize cycle time/material to minimize cost.
 Test all materials for coherence with known material property values.
 Rapid prototype the derived design for the shelving unit.
 Propose methods to increase incentives for the cradle-to-cradle life cycle.
The previous objectives were shown to be satisfied at project completion and/or addressed in the
recommendations section.

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Section I: Material Selection Analysis
Section I.1 discusses the steps taken to choose feasible materials for the customer’s desires.
Section I.2 shows all ecological audit findings and discusses the societal, economical, and
technical sustainability factors for each material.
Section I.1
Acquirement of customer needs began by formulating generalized survey questions pertaining to
qualitative aspects of the storage unit. The survey questions used can be found in Appendix A3
along with pie charts depicting the numerical results. The results obtained from the surveys are
shown below.
1. The storage unit should be stackable. Stackable was defined as the storage unit resting on
a support structure. However, the unit should not be free standing, so the next best
alternative was a wall mounted unit.
2. The storage unit must hold a minimum of 20 pounds.
3. The storage unit should cost between 0 to 100 USD.
4. The storage unit will most likely be used in a private room/study.
Following the establishment of basic product requirements, CES was utilized to help screen out
unqualified polymers [6]. The chart shown below represents the materials qualified after a
selection line and limitations were established (See Table 1 below).
Figure 1. Graph of Compressive Strength vs. Price for the CES class of polymers. The selection
line maintained a slope of 1.
Figure 1 shows only four polymers suitable for product development based off selection criteria
and the selection line established. For all selection criteria, refer to the Selection Criteria section.
Note the four materials: polyethylene, polycarbonate, polypropylene, and polystyrene.
In order to further screen feasible material choices, research was conducted through CES to gather
an understanding of all noted materials. Specifically, polystyrene was found to be unsuitable for
storage needs due to the brittleness of the material (prone to chipping). Polystyrene is mostly used
in small, rigid structures; such as pens, thus was not a feasible material choice for a shelf [6].

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The selection criteria for the three polymer choices can be seen in Table 1 below separated by
general properties, processability, durability, and eco-properties.
Shown below are the screening parameters utilized to choose the materials mentioned above.
Table 1. All polymer selection criteria used for material selection.
For general properties, price constraints for all polymers were limited to less than 5 U.S. dollars
per kilogram. The limit ensures cost effective material choices can be purchased within the
provided stipend of 100$.
Processability was limited by two processes: moldability and machinability. The values were
ranked on a numeric scale from one to five; a value of one indicated the material was not
recommended for the given process whereas a value of five corresponded to a highly recommended
process. Moldability was selected at maximum process values, because the prototype storage unit
will be designed for mass production. Castability and weldability were neglected in the limit stage
created for the selection criteria, because neither process was being considered for the product
production. Machinability was ranged between values of 4 and 5, which related to the assembly
process and means of fabricating such as lathing and milling. Slight machining such as drill holes
could pertain to the product design, therefore, the limit was included.
Durability was governed by three limits: Thermal tolerance, resistance to aqueous solutions, and
resistance to acids. The thermal tolerance described was constrained to a minimum temperature of
0°C and a maximum temperature of 150°C. The polymers selected were deemed excellent in terms
of withstanding aqueous solutions of water, water with salt, and wine. All solution criteria chosen
were typical to household use, thus common household items have the potential to interact with
the material. Also, the polymers selected were labeled excellent when in contact with acetic acid
(10%), citric acid (10%), and phosphoric acid (10%). The listed acids were included in the limit
parameters, because the acids were common in cleaning chemicals. Therefore, the product must
be compliant and resilient to the acids listed.
The final limit described was the labeled recyclable under eco-properties. Recyclability was an
important factor relative to sustainability. A recyclable product helps to complete the cradle-to-
cradle life cycle, thus, the final constraint limiting the polymer selection was if the material was
able to be recycled.

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Applying the above selection criteria with the CES software produced the polymers: polyethylene,
polycarbonate, polypropylene, and polystyrene. The four polymers listed met the specified
constraints described in the selection limits. As previously discussed, polystyrene was not
considered due to the known usage and properties of the material. Therefore, the selected materials
for the storage unit were: polyethylene, polycarbonate, and polypropylene.
Furthermore, after the materials were chosen, all known CES parameterized were tabulated and
the results are shown in Appendix A2.
Section I.2
The eco-audit was performed using the three chosen materials: polyethylene, polycarbonate, and
polypropylene. When performing the eco-audit, CES asked for several criteria to ground the
calculations. The criteria included the quantity of products, material used, mass of the product,
end life, transport of the product, and the product use. The following section includes the values
inserted for each criterion, explanations as to why each value was chosen, and presentation and
explanation of the eco-audit.
-Criteria
The criteria set for the audit constraints were the material, manufacturing process, and end life
for the product. The constraints included how many units of the product will be made, the
material used, the manufacturing process, mass of each unit, and the end life goals for the
product. Four concepts were developed using SolidWorks. Each concept included a shelf base
and three supports. The supports can be made out the same material as the shelf base or out of a
different material, such as a metal. For the eco-audit, the polymer concept designs 1 and 2
weighed approximately 16lb and were used as a baseline for comparison.
A quantity of 500,000 units were chosen to be manufactured, as determined from the project
guidelines. The three materials audited were the three materials chosen as mentioned above:
polypropylene, polycarbonate, and polyethylene.
The primary manufacturing process chosen was polymer extrusion, because the process is used
mainly to make polymer sheets and most large polymer objects [6]. Polymer extrusion was most
similar to injection molding, thus was a viable alternative for the analysis. Injection molding
requires the purchase of plastic pellets, which are heated and forced into a mold. A more in-depth
discussion of injection molding can be found in the Literature Review.
The end of life chosen was for the product to be downcycled. Recycle fractions for polymers are
very low compared to other materials, with PET being the highest at about 18%. Thus, recycling
polymers is expensive and can cost more than what the material is actually worth. Appropriately,
the method of downcycling the products was chosen, which is the most similar to recycling. The
polymer will be used for other products such as car upholsteries, park benches, etc.

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The criterion of transport was completed using all values given within the project instructions.
The transport type was given to be a 32 tonne truck and the distance traveled was 1,000 miles.
The use of the product was filled out using a combination of given values and assumed values.
First, the country electricity mix was chosen to be North American. The product life was agreed
to be 4 years, because the average college student attends school for 4 years. The criteria of
mobile mode and static mode were disregarded as specified in the directions.
An example of the criteria that was inserted into CES is shown in Figure 2. In this example,
polycarbonate was used as the material; the other two screens were the exact same, except
polyethylene and polypropylene were used as the material.
Figure 2. Polycarbonate criteria.
-Results
The results of each of the materials are summarized in Tables 2-4 where the energy in kcal,
energy %, CO2 in lb, and CO2 % were displayed for each process. As discussed previously, the
processes included material, manufacturing, transport, use, and disposal.
Table 2. Polypropylene results.

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Table 3. Polycarbonate results.
Table 4. Polyethylene results.
The above results showed that the best selection for energy is polypropylene, because PP used
the least total energy to manufacture, transport, and dispose. All of the EoL potentials for the
materials were negative, meaning that there was energy available within the product at the end of
products life. The more negative the value, the better the material was to downcycling. So, with
respect to downcycling, polycarbonate is the best option.
The carbon footprint in pounds of each material was also derived and the best option was
polyethylene, because PE created the least amount of carbon when manufactured, transported,
and used. With respect to EoL potential, the best material to choose would be polycarbonate,
because PC does not create any carbon when it is downcycled.
A better visual of the results for energy and carbon footprint are shown in Figures 3 and 4.
Figure 3. Energy summary chart for all three materials.

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Figure 4. CO2 footprint summary chart for all three materials.
To better compare the three materials with respect to total values and EoL potential, the results
shown above were inserted into Excel and a new graph was created. The new graph was created
by taking the total (for first life) values for each material and adding the first life totals to the
EoL potential for each material. If the EoL potentials were negative, the values would decrease
the total energy used or carbon created by the materials. The values and graph created are shown
below in Figure 5.
Figure 5. Table and chart created using overall energy and carbon footprint.

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From the chart in Figure 6, the best choice of material, with regards to an eco-audit, was
polyethylene. This material used slightly more overall energy than polypropylene, but created
significantly less carbon throughout the life of the material. Polycarbonate created very little
carbon throughout the process, however the overall energy needed is significantly higher than the
other two materials.
In conclusion, the eco-audit showed that the best material to choose was polyethylene. Compared
to polypropylene, PE used slightly more energy during the entire process, but created
significantly less carbon compared to polypropylene. PC did not create significantly more carbon
relative to polyethylene. Overall, considering the ranking for the eco-audit, the top choice was
polyethylene. The true best choice should depend on consumer needs and minimize
environmental impact. One may want a product that created the minimum amount of carbon
during its lifetime and remain tough; the next best choice would be polycarbonate. If the user
wanted a product that used the least amount of energy during the product life, then
polypropylene would be the next best choice according to the audit.
-Further Impacts
Not only will the material selection have an effect on the environment, but the chosen material
will affect the other three pillars of sustainability. With regards to the technical aspect, if the
material selection were based just on the eco-audit, the chosen material may not be that the
strongest material out of the considered materials. For instance, polyethylene was the most
environmentally friendly, but with regards to strength; PE could support the least amount of
weight. When the mechanical analysis was performed for each material, the analysis showed that
polyethylene was the weakest. Therefore, there must be trade-offs when selecting the material to
use. Depending on the desired trait, the product may be strong, but not environmentally friendly
or vice versa.
If polyethylene was chosen, the actual product would not last as long as intended. The targeted
life time of the shelving unit was to be 4 years, because that was the average time a person stays
at college. If polypropylene was chosen as the fabrication material, the product may not last 4
years. See the durability properties of all materials in Appendix A2. The user would, thus, either
buy a new shelf or get frustrated with the lack of strength and not purchase another unit.
With regards to social sustainability, customer dissatisfaction was not acceptable. A dissatisfied
customer was considered a loss in potential profits. Conclusively, some of the four pillars may be
positively affected by a certain design, while others may be negatively affected. Polycarbonate
was chosen, because PC optimizes the strength vs. sustainability objectives proposed.

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Section II: Description of Shelving Units
The four designs for each shelving unit were based off of known construction parameters. For
instance, the studs in common households are placed between 16” and 24” apart center to center
according to building code 5602.10.3 [1]. Given the shelf must be 45” wide, each support must
also be placed 16” apart center to center, as the most common stud spacing was found to be 16”
[16]. Appropriately, the following designs were produced with respect to the survey results
obtained; the shelf should be wall mounted in a private study/room (Appendix A3). Shown below
are the isometric 3D analytical shelving prototypes.
Prototype 1 (also referred to as design 1 or concept 1) is shown below. Design 1 was based off of
common household shelving systems.
Figure 7. The full-polymer shelving unit. Notice the shelf was supported by 3 truss-like
cantilever beams. A more involved representation of the model can be found in Appendix A1.
Note design one failed to meet the thickness requirements for injection molding (less than
0.150”) [4 and 5].
Prototype 2 shown below incorporated metal supports in order to support the shelf. Prototype
two could not be fabricated by injection molding, however, plastic machining was a viable
alternative for this concept.
Figure 8. The polymer-metal shelving unit. Note the shelf was supported by thin metal braces.
Again, see A1 for a more detailed view.
Note concept two was relatively simpler to machine, but required a material outside the polymer
class.

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Prototype 3 shown below performed the highest when compared to all other shelving prototypes.
However, concept 3 required a molding process that was unattainable.
Figure 9. The full polymer shelving unit with a bored shelf and triangular supports.
Note concept 3 could not be machined with any known fabrication methods except for plastic
machining due to the internal bores.
Prototype 4, the chosen alternative, appropriately follows all injection molding guidelines
established in the upcoming shelving analysis sections.
Figure 10. The full polymer shelving unit utilizing a ribbed shelving structure and the same
supports as Figure 9.
Note concept 4 was able to be injection molded accorded to the established injection molding
guidelines found in literature. Therefore, concept 4 was optimized for manufacturing purposes.
Furthermore, based off of the known max force values shown in Section II and design
specifications shown in Appendix A1, the prototypes should be used to support objects less than
12” in length from the wall and objects with a total weight less than the specified values in
Section 2. Note each prototype requires external components for mounting purposes. As such,
screws for mounting the supports to wall studs will need to be included and parameterized
appropriately.
The most applicable fabrication process for the shelving unit was derived through research and
using the CES software. For practical purposes, two potential fabrication methods for a

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polycarbonate (PC) shelving system will be determined. PC was chosen based off of mechanical
analysis results conducted, those of which can be found in the mechanical analysis section. The
constraints derived from supplied analytical models and known material properties are shown
below. For reference, the figure of the shelving system being discussed will also be shown
below. Notice the shelf and supports are separate components.
Figure 10. The discussed PC shelvng system.
 Material – PC, Thermoplastic (Use Tree-Limit, Polycarbonate)
 Shape – 3D solid
 Weight – 0.42kg (Support) and 4.89kg(Shelf)
 Maximum Thickness – 0.15inch [2]
 Precision – "(0.4mm) (Based on available shelving limitations)
 Surface Finish– 0.5-2μm (Assuming quality relative to ordinary machined parts)
 Batch Size – 500,000 (Base off of known project guidelines)
 Primary Shaping Method
Using CES Level 3 with the above limiting factors, the following primary shaping processes
could be used [6].
Primary Shaping Short list:
1. Compression Molding.
2. Injection Molding (Thermoplastics).
3. Thermoplastic Composite Molding (Ignored, since the material used will not be a
composite).
Thus, for primary shaping, compression molding and injection molding are viable alternatives.
Benefits and disbenefits of the end product for each method are discussed below.
Compression Molding (CM):
 Advantages – Cheaper relative to IM.
 Disadvantages – High tooling costs, limited to simpler shapes, thermoplastics require
heating and cooling cycles which reduce production rate.

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Injection Molding (IM):
 Advantages – High production rate, high quality, inserts and screw-threads are possible,
small angles are possible.
 Disadvantages – Capital and tooling costs are very high, thick sections are not
recommended, malfunctions during processing can be extremely dangerous.
For consolidation purposes, CM should not be used for the production of the shelving unit. The
CM production rate for thermoplastics was much slower relative to IM [6]. However, IM would
require higher startup costs for machinery. Thus, larger batch sizes will be needed to cover the
accumulation of costs. IM, appropriately, could cover large batch sizes due to IM having a high
production rate and high quality.
The IM complexity limits were of use due to the current design requiring screw holes. Even
though thick sections are not recommended for IM, CES confirmed that a component with a
thickness of 0.15” could be fabricated using IM. Note 0.15” was the maximum thickness in at
any given section of the design.
In conclusion, the largest impact to the end product of shelving unit would be the accompanying
costs of using IM. The price of the shelving unit will need to be fixed to off-set the operating
costs of using IM. Therefore, pricing of the shelving unit may be closer to the client based max
price of 100 USD.
Section III: Mechanical Analysis
A summary of derived mechanical analysis results is shown below separated into two sections.
For free body diagrams and the derivation of forces acting on each component, please see the
figures below. Supporting documentation for support analysis can be found in the support
analysis section. The full free body diagrams for all shelving systems can be found in Appendix
A4. Intermediate values used in calculation can be found in Appendix A5.
SHELVING ANALYSIS.1 (Designs 1 and 2 shown in Figures 7 and 8, respectively)
The loading scenarios described in the attached free-body diagrams included the weight of the
shelving unit, shown as a uniformly distributed load, as well as the maximum allowable point
load(s) spanning the shelving unit supports. The free-body diagrams shown were split into two
different orientations. The first orientation entailed modeling the ends of the shelving unit as
supported cantilever panels; the area spanned between the supports was modeled as simply
supported panels. Considering that the unit was symmetric, only one analysis was needed for
each scenario.
In order to determine the loading scenarios present at the shelving supports, the maximum
allowable loading force at the supports needed to be calculated. The shelving unit was required
to support various loading scenarios and therefore cannot yield under stated conditions. The

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maximum allowable loading conditions, with respect to yielding, were dependent on the
maximum allowable deflection of the unit.
Following standard practice, the maximum deflection was described to be less than 1/360 the
total length of the section being examined. The max deflection value for the cantilever scenario
was calculated as 0.0167 in. and the max deflection value for the simply supported beam
scenario was calculated as 0.0417 in. Following the standard values, deflection calculations were
used to solve for maximum allowable point loading conditions. The loading scenarios and their
corresponding deflection scenarios were described below:
The maximum deflection for the cantilever panel was described by a uniformly distributed load
and an end point load (as shown in the free body diagrams attached). Utilizing the free-body
diagram, deflection equations were incorporated to model the deflection scenario present in the
modeled cantilever panel. The conditions described produce the deflection scenario of:
, (Eq. 1)
Where delta represented the total deflection at the end of the panel by the summation of an
applied point load (at maximum deflection scenario located at the end of the panel) and a
uniformly distributed load. P was the unknown point load, l was the length of the panel, w
represented the weight of the panel, E was Young’s Modulus, and I was the second moment of
inertia for the panel.
Figure 11. Free-body Diagram of End Conditions for the Shelving Unit.
Following the free-body diagram above, the deflection scenario to calculate the maximum force
load to yield the panel was described by manipulating Equation 1, to solve for the unknown force
load P:
(Eq. 2)
P

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Inputting the appropriate variables into Equation 2 resulted in the maximum force load the
cantilever panel could withstand without yielding.
The maximum deflection for shelving sections spanning between the supports were modeled as
simply supported beams and can be described by a uniformly distributed load covering the entire
section and a point load located in at the center of the panel as shown below. Utilizing the free-
body diagram, deflection equations were incorporated to model the deflection scenario present in
the modeled panel. The conditions described produce the deflection scenario of:
, (Eq. 3)
Where delta represented the total deflection across the panel by the summation of an applied
point load (at the maximum deflection of a simply supported beam located at the center of the
panel) and a uniformly distributed load. P was the unknown point load, l was the length of the
panel, w represented the weight of the panel, E was Young’s Modulus, and I was the second
moment of inertia for the panel.
Figure 12. Free-body Diagram of Mid-panel Conditions for the Shelving Unit.
Following the free-body diagram above, the deflection scenario to calculate the maximum force
load to yield the panel was described by manipulating Equation 3, to solve for the unknown force
load P:
(Eq.4)
simply supported panel could withstand without yielding. Table 5 below shows the resulting
values corresponding to the selected materials by solving Equations 2 & 3 for the maximum
point loads with the respected scenarios mentioned above:
P

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Table 5. Maximum Force Loads for Modeled Scenarios
Note the full Excel sheet calculations can be found located in the Appendix A5.
From Table 5 above, the resulting force values for variable P can be seen; that is, the forces
shown were the maximum allowable loads that the shelf can be subjected to before yielding.
These calculations were, as described earlier, based off of maximum conditions located at the
shelving units’ most vulnerable points. Therefore, the shelf can withstand the described forces at
the locations. However, to determine the total amount of force the shelf can withstand, a
mechanics analysis was performed to determine the allowable forces provided by the shelving
supports, shown below.
Also note, the calculations described absolute max loading conditions without yielding; the
values were calculated based off of modeling the ends of the shelving unit as panels—not the
designed irregular shape. Therefore, the loading conditions should be considered to be less than
that of allowable loading conditions. Also, because deflection was described with respect to
Young’s modulus, the selected material should resemble the largest value for Young’s modulus,
thus providing the largest magnitude of loading support.
SUPPORT ANALYSIS.1 (Designs 1 and 2 shown in Figures 7 and 8, respectively)
The supporting structures of the shelf forces must be parameterized appropriately in order to not
fail. Shown below are the methods taken to determine the max allowed force for both types of
supporting structures.
-Metal Braces
Following the same procedure to determine the maximum load applied for the modeled
cantilever panel, the support forces can be found utilizing a similar method. Notice, that for
concept two, the metal supports were designed as thin connected metal panels. Thus, the
supports were modeled as two parallel plates and a cantilever beam under deflection. By solving
for the maximum load at which the panel yields, the maximum load the supports can hold was
calculated.
The maximum deflection for the cantilever support beam was described by a uniformly
distributed load and a point load, as shown in the free body diagrams below. Utilizing the free-
body diagram, deflection equations were incorporated to model the deflection scenario present in
the modeled cantilever support. The conditions described produce the relation shown below.
, 3 (Eq. 5)
Material Young's Modulus, E (psi) Moment of Inertia (I), Iyy (in^4) Max force, lbf (Cantilever) Max force, lbf (Panel)
Polypropylene 177500 0.125 4.204 9.265
Polyethylene 110050 0.125 2.252 4.269
Polycarbonate 322000 0.125 8.385 19.969

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Where delta represented the total deflection across the support by the summation of an applied
point load and a uniformly distributed load, P was the unknown point load, l was the length of
the panel, a & x were the distance to the point load, w represented the weight of the panel, E was
Young’s Modulus, and I was the second moment of inertia.
Figure 13. Free-body Diagram of Metal Support.
Following the free-body diagram directly above, the deflection scenario to calculate the
maximum force load to yield the supports were described by manipulating Equation 5 to solve
for the unknown force load P.
(Eq. 6)
supports could withstand without yielding. Table 6 below shows the resulting values for the
maximum point load allowable for the metal supports:
Table 6. Maximum Force Loads for Metal Supports.
Note the full Excel sheet calculations can be located in Appendix A6.
As seen in Table 6, the maximum force the supports can maintain is roughly 300 lbf. Thus, the
calculated loading scenario for the supports are greater than those loads provided at the middle
and end sections of the shelving unit. Therefore, the metal supports can support the shelf with
applied loads described in Tables 5 & 6 at their respected locations.
Material Young's Modulus, E (psi) Moment of Inertia (I), Iyy (in^4) Max force, lbf (Cantilever)
Cast Stainless Steel 27557170.16 0.0247 300.209
P

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-Polymer Truss-like Supports
In order to calculate the maximum force that the polymer truss-like supports could support, the
frame must first be analyzed. When analyzing the frame, the assumption was made that the joints
of the support were rigid and, as such, the support would fail when one of the three highlighted
areas, seen below, would fail. The support can be seen below in Figure 14.
Figure 14. The free body diagram for the truss-like support.
The three main areas of concern for the shelf to fail are the areas in red. It is assumed that these
three boxes can be looked at as a cantilever beam, a simply supported beam, and as a vertical
column respectively.
The cantilever beam (box one in Figure 14) is displayed below in Figure 15 where P represented
the load from the shelf and Po represented the density of the material the support is made from
times the cross sectional area of the beam.
Figure 15. The free body diagram of a cantilever beam in the truss-like support.
The max allowable deflection of a beam, , was found using Equation 7.
(Eq.7)
Po
P

Page 21 of 38

Where L was the length of the beam.
Using this maximum allowable deflection, the maximum point load that the beam could handle,
P, was found using Equation 8.
∗ 3 / (Eq.8)
Where E was the modulus of elasticity for each material, I was the moment of inertia for the
beam, and Po was the distributed load as described previously.
The results of Equation 8 for each material, which described the maximum allowable point load
as shown in Figure 15, can be seen below in Table 7.
Table 7. Cantilever analysis on truss-like support.
As seen from Table 7 polypropylene, polyethylene, and polycarbonate can support
approximately 1.5 lbf, 1 lbf, and 3 lbf respectively.
The simply supported beam (box two in Figure 14) is displayed below in Figure 16 where P
represented the load from the shelf and Po represented the density of the material the support is
made from times the cross sectional area of the beam.
Figure 16. The free body diagram of the simply supported beam in the truss-like support
The max allowable deflection of a beam, , was found using Equation 9.
(Eq.9)
Where L was the length of the beam.
Po
P

Page 22 of 38

Using this maximum allowable deflection, the maximum point load that the beam could handle,
P, was found using Equation 10.
∗ 48 / (Eq.10)
Where E was the modulus of elasticity for each material, I was the moment of inertia for the
beam, and Po was the distributed load as described previously.
The results of Equation 10 for each material, which described the maximum allowable point load
as shown in Figure 15, can be seen below in Table 8.
Table 8. Simply supported beam analysis on truss-like support.
As seen from Table 8 polypropylene, polyethylene, and polycarbonate can support
approximately 1650 lbf, 1000 lbf, and 3000 lbf respectively.
The diagonal support (box three in Figure 14) was modeled as a vertical column and the critical
load was modeled with Euler’s formula, as derived below. In order to determine the correct
formula, the slenderness ratio must be compared to the column constant.
The radius of gyration, r, was found using Equation 11.
/ (Eq.11)
Where I was the moment of inertia and A was the cross-sectional area of the column.
The slenderness ratio, S.R., was found using Equation 12.
. . (Eq.12)
Where K was the end condition constant for the column and L was the length of the column.
The column constant, Cc, was found using Equation 13.
(Eq.13)
Where E was Young’s modulus of the material and σy was the yield strength of the material.
Since for all three materials the slenderness ratio was larger than the column constant; the
column was considered relatively long and was analyzed using the Euler formula seen below in
Equation 14.

Page 23 of 38

(Eq.14)
Where Pcr was the critical load on the column before it could fail.
The maximum supported force of the shelf, Fs, by all three supports was written in terms of the
critical load of an individual column according to the angle, θ, made between the connection of
the support and horizontal beam as seen in Equation 15.
3 (Eq.15)
The results of the above equations can be found below in Table 9.
Table 9. Maximum Force Loads for Polymer Supports.
As seen in Table 9, the polypropylene, polyethylene, and polycarbonate supports could support a
maximum force of approximately 1375 lbf, 850 lbf, and 2500 lbf respectively.
Through this analysis the truss-like support structure was limited due to the front cantilever
section. This part of the support limited the design of the shelf so that it became the limiting
factor of the entire shelving unit.
SHELVING ANALYSIS.2 (Designs 3 and 4 shown in Figures 9 and 10, respectively)
The previously proposed designs were unable to be fabricated with standard injection molding
procedures. For instance the standard recommended thickness range for polycarbonate was 0.04”
to 0.15” [2]. Injection molding has high start-up costs due to the initial cast-molds needed to
begin processing. However, over time, the startup cost for injection molding has potential to be
offset by the savings relative standard machining (milling and lathing being the only other
feasible method to produce the shelving units) [3]. Thus, injection molding was determined to be
the most cost efficient option to produce mass amounts of product.
In general, injection molding has a lower tolerance and a rougher finish when compared to
standard machining. Since Designs 3 and 4 both have no need for precision greater than 0.005”,
injection molding was still a viable alternative.
Injection molding requires a large amount of guidelines to be met in order to confirm successful
product fabrication. Design criteria discussed below can be found by referring to the reference
section [4 and 5]. In summary, drafts, fillets, radii, gussets, ribs, intersecting thicknesses, and
overall product dimensions must be considered when designing a product for injection molding.

Page 24 of 38

The following diagrams show the cross sectional area for designs 3 and 4. Equations 1-6 were
still valid for the panel force analysis, however, the moment of inertia differs from the previous
designs.
Figure 17. The bored shelving unit design.
Figure 18. The ribbed shelving unit design.
Note the height of the cross section in Figure 18 (concept 4) was optimized to minimize material
while still meeting the needed 20lbf minimum support. The minimum moment of inertia for the
ribbing structure must be 0.066 in order to support 20lbf according to the Excel equation
solver. Thus, due to the design guidelines discussed below, only the height of the shelf could be
optimized. The minimum height value to achieve the 20lbf was found to be approximately
0.625" by constructing iterations of the SolidWorks model. Concept 4 utilized a height 0.65" to
ensure the minimum standard was achieved.
The previous cross sections were used to determine the moment of inertia for each respective
design.
The following parameters were determined based off of known design guidelines for injection
molding and were described sufficiently [4 and 5].
Design Guidelines
 Inner radii: 0.5*t, where t was the general thickness of the design and t equaled 0.15” for
both designs.
 Outer radii: 1.5*t
 Rib Spacing (RS): RS>2*t, 0.5” or 0.68” depending on design characteristics.
 Rib Width (RW): 40-60% of t, bored shelving unit RW = 0.1”, ribbed shelving unit RW
= 0.075”.
 Rib Height (RH): RH 3*t. RH = 0.45”.

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 Gussets in Supports: Spacing = 0.5”, Length = 0.5”, width = 0.45”, gusset thickness =
0.075”, fillet radius = t*0.25, and spacing = 0.15”*2 (See Appendix A8 for an argument
for gusset implementation).
 Draft: Between 1° and 2° for all components.
For design 3, the following max force allowed is shown below with accompanying
intermediate results. Note by this time in the design process, polycarbonate was chosen as the
appropriate material, thus only the average polycarbonate Young’s modulus E was used [6].
Table 10. The intermediate values and max force for design 3.
Panel Deflection Max, in Length, in Ixx, in^4 Eavg, psi Pmax, lbf
   0.04 13.70 0.33 322000.00 75.83
Ends Deflection Max, in Length, in Pmax, lbf
   0.01 5.35 31.08
For design 4, the following max force allowed is shown below with accompanying
intermediate results.
Table 11. The intermediate values and max force for design 4.
Panel Deflection Max, in Length, in Ixx, in^4 Eavg, psi Pmax, lbf
   0.03 11.88 0.06 322000.00 24.1
Ends Deflection Max, in Length, in Pmax, lbf
   0.01 5 8.48
Thus, design 3 seemingly was the most appropriate choice based off of derived force values.
However, design 3 had a major flaw in relation to draft required for injection mold extraction.
Design 3 would require the draft to be placed along the large faces of the shelf, thus causing the
main faces of the shelf to be non-uniform. The main faces for a shelf are necessarily flat, thus
design 3 was disregarded.
Design 4 is capable of being extracted perpendicular to the main face, thus the drafts were
appropriately placed on the sides and the ribbing. For an example, see Figure 19 below.
Figure 19. Displays the draft on the outside edge and inner ribbing.

Page 26 of 38

Following the shelf analysis, the support analysis was conducted for feasibility. Note the
maximum load experienced by design 4 at any given time should not exceed 50lbf Thus, the
supports should support at least 17 each (since there were 3 supports in this design).
SUPPORT ANALYSIS.2 (Designs 3 and 4 shown in Figures 9 and 10, respectively)
Again, the supporting structures shown in Figures 9 and 10 were designed with injection
molding in mind. Each support has an inward draft with respect to extraction. The supports were
modeled as a cantilever beam with a linearly varying depth with respect to cross sectional area.
Common practice dictates the moment of inertia be taken at the distance to the centroid of the
cantilever shape for a minimum bound of derived values [7]. For reference, a free body diagram
of the support is shown below. For the lowest possible sustainable force, only one triangular
cantilever section was modeled.
Figure 20. The free body diagram for the support structure.
The assumed moment of inertia (shape shown with the dashed line in Figure 18), thus, was that
of a rectangular support of thickness 0.15”, length 11.15”, and depth of 1.33”.
Table 12. The minimum sustainable force by one support.
Max Deflection, in thickness, in depth, in I, in^4 length, in Pmin, lbf
0.031 0.15 1.33 0.023 11.15 20.64
Note, the design will succeed based on the estimations above, since each support could support,
at a minimum, 20lbf (exceeding the 19lbf estimated above Table 5).
Therefore, design 4, shown in Figure 10, will be the design pursued for final product fabrication.

Page 27 of 38

Mounting Analysis (Screw Selection)
In order to properly mount the shelving unit to specified wall studs, the selection of screws was
necessary. The screws were selected based on known standards discussed below and qualitative
reasoning.
The shelf will support, at maximum, a total of 60lbf. Each screw was specced to support the 60
lbf maximum load. Thus, the shear force in the screw member is also 60lbf.
Using the Fastenal Handbook and NDS building codes, the following relations were derived. The
actual shear stress in a screw member was as follows.
4 ∗ (Eq. 12)
Where was the actual shear stress in a screw member of circular cross sectional area, was
the circular cross section area for each screw [17].
The Fastenal Handbook stated the acceptable limit for screw shear stress could be approximated
as follows.
∗ 0.6 (Eq. 13)
Where was the acceptable shear stress and was the ultimate strength of low-carbon steel
(material of commonly used screws, 50ksi) [18, 6]. Thus, = 30ksi.
Now, the following relations was derived in order for a screw to be considered as a feasible
alternative.
(Eq. 14)
The screws to be considered for selection were tabulated using the information available from
Bolt Depot [19]. The results obtained were as follows.
Table 13. The screw diameters (D), calculated shear stress, safety factor in relation to the
acceptable shear stress, and the known diameters of available washers. Note Fender washers
were chosen due to out diameter being larger relative to normal washers [19].
Screw Size D, in , ksi Safety Factor , in
#2(Cannot use Fender washer) 0.086 13.77 2.18 Void
#6 0.138 5.35 5.61 0.625
#8 0.164 3.79 7.92 0.75
#10 0.19 2.82 10.63 1

Page 28 of 38

Note the largest possible washer, in relation to screws sizes shown in Table 11 that was able to
fit between the gussets of concept 4, was 1in in diameter. In order to maximize the amount of
surface contact from the screw member, the largest diameter washer possible was chosen, which
allowed screw alternatives to be screened.
The maximum amount of surface contact at the washer to support interface was necessary in
order to minimize the stress around the screw holes. However, the previous statement was made
on a qualitative basis and optimization of the washer surface area should be conducted in further
studies.
Section IV: Synthesis of Analysis into Design
In order to choose the best alternative for the shelving material, a reflection on obtained
mechanical analysis results, ecological audit results, and known tabulated material properties
was necessary. The following sections describe the screening of polycarbonate, polyethylene,
and polypropylene in order to choose one material for further product development.
Mechanical Analysis
Polycarbonate, from the mechanical analyses, supported the largest applied loads, primarily due
to Polycarbonate’s’ inherently large Young’s Modulus value. When calculating the applied force
loads, the limiting factor for such calculations were dependent on Young’s modulus values. In
turn, Polycarbonate had the largest of the three materials chosen. Therefore, it follows
Polycarbonate was the material which could support the greatest loads.
Polypropylene fell within the middle margin of the materials on the basis of the mechanical
analyses. The values calculated for Polypropylene rested between Polycarbonate and
polyethylene respectively. Therefore, Polypropylene remained relatively neutral with respect to
the other material choices.
Choosing polyethylene resulted in supporting the lowest applied load values, which was
correlated to polyethylene having a lower Young’s Modulus value. Thus, polyethylene suffered
in terms of supporting applied loads when compared to other materials chosen for the shelving
unit.
Ecological Audit
Polycarbonate created the least amount of carbon throughout its lifetime and did not require
significantly more energy than the other two materials. Polycarbonate used a large amount of
energy to produce and use, but created small amounts of overall carbon during the product life
cycle. Polypropylene was the opposite; PP does not require as much energy as polycarbonate, but
created large amounts of carbon throughout its entire lifecycle.
Throughout the lifecycle process, polypropylene required the least amount of energy, but
produced the most amount of carbon. The overall calculations of carbon and energy required
showed that polypropylene was not a viable choice regarding environmental sustainability.

Page 29 of 38

In regards to environmental sustainability, polyethylene was the top material to choose. PE
required slightly more energy during the product lifetime, but created very little carbon during
the overall lifecycle. The previous mentioned factors led PE to be the top choice in regards to the
ecological audit.
Material Properties (Refer to Appendix A2)
PC had the highest maximum Young’s Modulus (E= 2.44 Gpa). Thus, PC could support the
highest load with respect to the derivations produced in Section II. However, PC also cost the
most per unit kg. Remember, in order to stay within the clients budget, the shelving system
should cost less than 100 USD. Appropriately, the shelving unit was less than 20kg, causing the
cost to be less than 100 USD. All PC shelving units were found to support over 40 Lbf (See
Table 5), satisfying the customer need requirement of 20 .
The max E for polypropylene was 1.55 Gpa. Thus, if the shelving unit was made from
polypropylene, the shelving unit could not hold an appropriate amount of weight with respect
client satisfaction (could only support 18.4 lbf, referring to Table 5).
PE was not a feasible alternative due to the amount of weight supported when compared to PC
and PP. PE had the lowest max E (0.896 Gpa). Thus, PE was found to only be able to support a
max of approximately 10Lbf. Again, see Table 5 for all found shelving forces.
Note each material above maintained similar material properties throughout screening (Refer to
Section 3). Thus, when considering fabrication benefits between materials, all materials were
machined similarly. SolidWorks fabrication analysis was used to test the fabrication capabilities
of each component. According to SolidWorks, the polymer components were able to be milled
and lathed and the steel component was made using sheet metal processing. The polymer and
steel components were parameterized based off of known sheet thicknesses sold by
manufactures.
Injection molding was viable alternative relative to the design practices used in concept 4 (Figure
10). Injection molding was most viable when cycling time was minimized and product changes
are unnecessary. As such, a design which can be molded in one molding instance would be the
most cost and energy efficient option.

Page 30 of 38

Conclusions and Recommendations
In conclusion, based on the above summaries for the three materials and when considering all
aspects mentioned throughout the above documentation, polycarbonate will be the material
chosen for further product development. PC was the only feasible alternative when considering
acquired customer needs. Future work involves analyzing injection molded material samples in
order to further verify material properties.
Recommendations include optimizing the thicknesses parameterized for the injection molding
process to use the least amount of material and still support the anticipated load. A design which
can be easily molded in one molding instance should be considered, as the savings and negative
impacts would be maximized and minimized, respectively. Incentives to increase recycling
awareness should be displayed on packaging and made easily accessible. For instance, if the
product was returned to the company after the useful life duration, a discount on the next model
would be made available. Lastly, a scale model of concept four should be created to demonstrate
feasibility.
References (Number System: In-Text Citations)
[1] N.p. Web. 30 Mar 2014. <http://www.mass.gov/eopss/docs/dps/780-cmr/780056b.pdf>.
[2] "Basics of Injection Molding Design." Quickparts. 3DSystems, n.d. Web. 30 Mar 2014.
<http://www.quickparts.com/LearningCenter/BasicsofInjectionMoldingDesign.aspx#wall
thickness>.
[3] Gerard, Katie. "Plastic Injection Molding vs. Plastic Machining: How to Decide." Craftech
Industries INC. N.P., 06 Sep 2013. Web. 30 Mar 2014.
<http://info.craftechind.com/blog/bid/333498/Plastic-Injection-Molding-vs-Plastic-
Machining-How-to-Decide>.
[4] "Injection Molding Design Guidelines." GE Plastics. General Electric Co. Web. 30 Mar
2014. <http://www.polymerhouse.com/datasheets/GE_Thermo Plastic
DesignGuide_[1].pdf>.
[5] "Injection Molding Design Guidelines."Solid Concepts Inc. Web. 30 Mar 2014.
[6] "Granta's CES EduPack." Granta Material Intelligence. Granta Design Limited 2013.
[7] Paglietti, A, and G Carta. "Remarks on the Current Theory of Shear Strength of Variable
Depth Beams."Bentham Science. Department of Structural Engineering, University of
Cagliari, Italy, 02 Jan 2009. Web. 30 Mar 2014.
<http://www.benthamscience.com/open/tociej/articles/V003/28TOCIEJ.pdf>.
[8] "History of Polymers and Plastics for Teachers." American Chemistry. American Chemistry
Council, Inc., n.d. Web. 1 Apr 2014. <http://plastics.americanchemistry.com/Education-
Resources/Hands-on-Plastics/Introduction-to-Plastics-Science-Teaching-

Page 31 of 38

Resources/History-of-Polymers-Plastics-for-Teachers.html>. [9] Rosato, Dominick V.,
Donald V. Rosato, and Marlene G. Rosato, eds. Injection molding handbook.
Springer, 2000.
[9] Rosato, Dominick V., Donald V. Rosato, and Marlene G. Rosato, eds. Injection molding
handbook. Springer, 2000.
[10] Kopeliovich, Dmitri. "Methods of Polymers Fabrication."Subs Tech. N.P., 27 Jul 2013.
Web. 1 Apr 2014.
<http://www.substech.com/dokuwiki/doku.php?id=methods_of_polymers_fabrication>.
[11] "ASPEC Secondary Machining of Plastic Parts." ASPEC. N.p. Web. 1 Apr 2014.
<http://www.aspecplastics.com/secondary-machining.html>.
[12] Admin, . "EPP Corporation." Plastic Machining: Custom Plastic Components- Molding vs.
Machining. EPP Corporation-Plastic Machining Experts, 29 Jun 2011. Web. 1 Apr 2014.
<http://eppcorp.com/custom-plastic-components-molding-vs-machining-2/>.
[13] "Energy Efficiency in Plastics Processing." Tangram. Tangram Technologies. Web. 1 Apr
2014. <http://www.tangram.co.uk/TI-Energy Worksheets (Plastics) - Tangram.PDF>.
[14] "Injection Molding." 3D Systems. N.p. Web. 1 Apr 2014.
<http://www.3dsystems.com/solutions/injection-molding>.
[15] BPF Training. British Plastics Federation. Web. 1 Apr 2014.
<http://www.bpftraining.com/library/energy_efficiency_in_injection_moulding>.
[16] Stansley, Kit. "Three Ways to Find a Wall Stud." Bobvila. Bobvila, n.d. Web. 20 Apr.
2014. <http%3A%2F%2Fwww.bobvila.com%2Farticles%2Fhow-to-find-a-wall-
stud%2F%23.U1QZTfldXCs>.
[17] Wood Council, American. "National Design Specification." NDS for Wood Construction.
AWC, 1 Jan. 2005. Web. 28 Apr. 2014.
<http://www.awc.org/pdf/NDSCommentary2005.pdf>.
[18] "Fastenal Industrial and Construction Supplies." Technical Reference Guide. Fastenal, 1
Jan. 2005. Web. 28 Apr. 2014.
<http://www.fastenal.com/content/documents/FastenalTechnicalReferenceGuide.pdf>.
[19] "Bolt Depot." Bolt Depot.com. Bolt Depot, 1 Jan. 2014. Web. 28 Apr. 2014.
<http://www.boltdepot.com/Fender_washers_Stainless_steel_18-8.aspx>.

Page 32 of 38

Appendix
A1
Please see labeled attachments for the CAD drawings of Figures 7, 8, 9, and 10.
 Attachment 1: Shows the support structure for Figure 7.
 Attachment 2: Shows the shelving structure for Figure 7.
 Attachment 3: Shows the support structure for Figure 8.
 Attachment 6: Shows the support structure for Figure 9 and Figure 10.
A2
All CES values for each material are shown below [6].
Polypropylene Values:
General Properties Min Max Avg. Units

Density 890 910 900 kg/M^3
Price 1.92 2.21 2.065 USD/kg

Mechanical Properties Min Max Avg. Units

Young's Modulus 0.896 1.55 1.223 Gpa
Shear Modulus 0.316 0.548 0.432 Gpa
Bulk Modulus 2.5 2.6 2.55 Gpa
Poisson's Ratio 0.405 0.427 0.416 Gpa
Yield Strength (elastic) 20.7 37.2 28.95 Mpa
Tensile Strength 27.6 41.4 34.5 Gpa
Compressive Strength 25.1 55.2 40.15 Gpa
Elongation 100 600 350 %
Hardness 6.2 11.2 8.7 HV

Thermal Properties Min Max Avg. Units

Max Service
Temperature 100 115 107.5 °C
Min Service Temperature ‐123 ‐73.2 ‐98.1 °C
Thermal Conductivity 0.113 0.167 0.14 W/m.°C
Specific Heat 1.87E+03 1.96E+03 1915 J/kg.°C

Page 33 of 38

Electrical  Properties Min Max Avg. Units

Conductor/Insulator Good Insulator
Electrical Resistivity 2.1 2.3 2.2 μohm.cm

Optical Min Max Avg. Units

Transparency Translucent
Refractive Index 1.48 1.5 1.49 ‐

Processability Min Max Avg. Units
1 =
Low 5
= High
Castability (1‐5) 1 2 1.5 ‐
Moldability 4 5 4.5 ‐
Machinability 3 4 3.5 ‐
Weldability 5 ‐ ‐ ‐

Eco Properties Min Max Avg. Units

Embodies Energy 75.7 83.7 79.7 MJ/kg
CO2 Footprint 2.96 3.27 3.115 kg/kg
Recyclable (Yes/No) Yes ‐ ‐ ‐
Polyethylene Values:

Density 939 960 949.5 kg/M^3
Price 1.176 1.94 1.558 USD/kg


Young's Modulus 0.621 0.896 0.7585 Gpa
Yield Strength (elastic) 17.9 29 23.45 Mpa
Tensile Strength 20.7 44.8 32.75 Gpa
Compressive Strength 19.7 31.9 25.8 Gpa
Hardness 5.4 8.7 7.05 HV


Max Service
Temperature 90 110 100 °C

Page 34 of 38


Electrical Resistivity 3.30E+22 3.00E+24 1.52E+24 μohm.cm


Transparency Translucent

1 =
Low 5
= High
Castability 1 2 1.5 ‐


Embodies Energy 77 85.1 81.05 MJ/kg
Recyclable (Yes/No) yes    ‐ ‐
Polycarbonate Values:

Density 1.14E+03 1.21E+03 1175 kg/M^3
Price 4.1 4.51 4.305 USD/kg


Young's Modulus 2 2.44 2.22 Gpa
Yield Strength (elastic) 59 70 64.5 Mpa
Tensile Strength 60 72.4 66.2 Gpa
Compressive Strength 69 86.9 77.95 Gpa
Hardness 17.7 21.7 19.7 HV


Max Service
Temperature 101 144 122.5 °C

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Electrical Resistivity 1.00E+20 1.00E+21 5.5E+20 μohm.cm


Transparency Optical Qualtiy

1 =
Low 5
= High
Castability 1 2 1.5 ‐


Embodies Energy 103 114 108.5 MJ/kg
Recyclable (Yes/No) yes    ‐ ‐
A3
The list of survey questions in entirety are shown below. Note survey questions were approved by
engineering faculty available for consultation.
1. When storing items, what type of unit would you prefer? “unit(explanation/visual)”
A. Free Standing (supported by itself) B. Wall Mounted C. Stackable (rests on support
structure) D. Free Hanging (chandelier)
2. How much weight would you store on/in your preferred unit? “weight(approximation of object
weight)”
A. 0-10lb (a few tools) B. 10-15lb (bowling ball) C. 15-20lb (a few textbooks)
D. 20-30lb (3 gallons of water)
3. How much would you be willing to pay for your desired unit?
A. 0-50$ B. 50-100$ C. 100-150$ D. 150-200$ E. $ > 200$
4. Where would you want your desired unit?
A. Public Room B. Private Room C. Utility Room D. Outside E.
Other:_______________________
5. Please flip the survey over and write any other queries or/and expand your answer choice(s).

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The following figure depicts the results obtained from the surveys.
Figure 21. Displays percent responses for the survey questions directly above.
Figure 21 breaks down each survey question into percent pie charts for pictorial representation of
the results. Notice in Question 1’s responses, A and C were split evenly with a majority of 40%.
However, according to the given design guidelines, the storage unit should not be self-supported.
Thus, a wall hanging unit was the chosen appropriate alternative.
A4
The full free body diagram for both shelving systems.
Figure 22. The full free body diagram for both shelving units.

Page 37 of 38

A5
The intermediate values used in determine allowable forces acting on the shelf.
Figure 23. Intermediate calculations used as stated above.
A6
The intermediate values for use in determining the max allowable load for the metal brace.
Figure 24. Intermediate calculations used as stated above.
A7
The attachments labeled 1-7 are shown directly after as referenced by A1. Attachments 1-7
corresponded to pages 39-45, respectively.

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A8
The qualitative benefits for implementing gussets into the chosen shelving supports are depicted
below.
Figure 25. Stress locations when a 50lbf horizontal load is applied horizontally.
Figure 25 displaces the stress locations for when the supports undergo an unintended supporting
scenario. The scenario depicted was most similar to a horizontal force being applied to the
shelving supports, most likely by the swaying of the shelf. Note the model including the gussets
was able to minimize the amount of stress near the wall-support interface.
QED

10.500
2.452
0.500
12.500
3.106.90
9.00
R0.25
R0.25
R1.00
0.895.46
5.32
1.50
4.38
R2.00
R2.00
7.00
7.54
8.00
0.250
0.500
0.500
10.000
10.500
2
X
0.250
0.500
0.500
10.000
10.000
10.500
2 X 0.250
0.250
2.45
4.10
7.64
8.000.50 0.500
12.000
12.500
5.50
9.50
Top
Front
Back
+-0.005in
Attachment 1
DO NOT SCALE DRAWING
Support1
SHEET 1 OF 1
UNLESS OTHERWISE SPECIFIED:
SCALE: 1:5 WEIGHT:
REVDWG. NO.
A
SIZE
TITLE:
NAME DATE
COMMENTS:
Q.A.
MFG APPR.
ENG APPR.
CHECKED
DRAWN
FINISH
MATERIAL
INTERPRET GEOMETRIC
TOLERANCING PER:
DIMENSIONS ARE IN INCHES
TOLERANCES:
FRACTIONAL
ANGULAR: MACH BEND
TWO PLACE DECIMAL
THREE PLACE DECIMAL
APPLICATION
USED ONNEXT ASSY
PROPRIETARY AND CONFIDENTIAL
THE INFORMATION CONTAINED IN THIS
DRAWING IS THE SOLE PROPERTY OF
<INSERT COMPANY NAME HERE>. ANY
REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
<INSERT COMPANY NAME HERE> IS
PROHIBITED.
5 4 3 2 1

8.664
45.000
6.250
6.000
12.000
6.7522.25
22.75
38.25
45.00
2.60
R0.10Sym
45.000
0.500
+-0.005in
Attachment 2
Shelf1
SHEET 1 OF 1
SCALE: 1:10 WEIGHT:
REVDWG. NO.
A
SIZE
TITLE:
NAME DATE
COMMENTS:
Q.A.
MFG APPR.
ENG APPR.
CHECKED
DRAWN
FINISH
MATERIAL
INTERPRET GEOMETRIC
TOLERANCING PER:
TOLERANCES:
FRACTIONAL
ANGULAR: MACH BEND
TWO PLACE DECIMAL
THREE PLACE DECIMAL
APPLICATION
USED ONNEXT ASSY
PROHIBITED.
5 4 3 2 1

0.125 11.875
12.000
1.000
1.125
1.625
1.750
2.750
0.125
1.000
12.000
0.500
1.000
0.500
1.000
0.250Sym
0.500
1.000
0.500
1.125
1.625
2.250
2.750
2 X
0.250
+-0.005in
Attachment 3
support 3
SHEET 1 OF 1
SCALE: 1:5 WEIGHT:
REVDWG. NO.
A
SIZE
TITLE:
NAME DATE
COMMENTS:
Q.A.
MFG APPR.
ENG APPR.
CHECKED
DRAWN
FINISH
MATERIAL
INTERPRET GEOMETRIC
TOLERANCING PER:
TOLERANCES:
FRACTIONAL
ANGULAR: MACH BEND
TWO PLACE DECIMAL
THREE PLACE DECIMAL
APPLICATION
USED ONNEXT ASSY
PROHIBITED.
5 4 3 2 1

8.485sym
6.000sym
12.000
6.000sym
45.000
11.875Sym
6.000
7.000
22.000
23.000
38.000
39.000
45.000
0.125
0.625
0.750
+-0.005in
Attachment 4
Shelf 3
SHEET 1 OF 1
SCALE: 1:10 WEIGHT:
REVDWG. NO.
A
SIZE
TITLE:
NAME DATE
COMMENTS:
Q.A.
MFG APPR.
ENG APPR.
CHECKED
DRAWN
FINISH
MATERIAL
INTERPRET GEOMETRIC
TOLERANCING PER:
TOLERANCES:
FRACTIONAL
ANGULAR: MACH BEND
TWO PLACE DECIMAL
THREE PLACE DECIMAL
APPLICATION
USED ONNEXT ASSY
PROHIBITED.
5 4 3 2 1

45.00
11.50
0.1311.18
11.40
0.10
0.60
0.70
0.15Sym
0.60Sym
0.75Sym
11.50
R0.23Sym
0.75
0.38
45.00
+-0.005in
Attachment 5
Shelf 2
SHEET 1 OF 1
SCALE: 1:10 WEIGHT:
REVDWG. NO.
A
SIZE
TITLE:
NAME DATE
COMMENTS:
Q.A.
MFG APPR.
ENG APPR.
CHECKED
DRAWN
FINISH
MATERIAL
INTERPRET GEOMETRIC
TOLERANCING PER:
TOLERANCES:
FRACTIONAL
ANGULAR: MACH BEND
TWO PLACE DECIMAL
THREE PLACE DECIMAL
APPLICATION
USED ONNEXT ASSY
PROHIBITED.
5 4 3 2 1

R0.075
R0.075
0.17
TRUE R0.08Sym
R0.23
R0.23
R0.30
R0.30
1.57°
0.17
0.45
0.66
0.56
0.73
0.89
3.34
3.37
3.41
3.76
3.81
3.92
1.85
1.55
+-0.005"
Inches
Attachment 6
Drawing represents an example of pertinent parameters
for injection molding process
Support 2
SHEET 1 OF 1
SCALE: 1:5 WEIGHT:
REVDWG. NO.
A
SIZE
TITLE:
NAME DATE
COMMENTS:
Q.A.
MFG APPR.
ENG APPR.
CHECKED
DRAWN
FINISH
MATERIAL
INTERPRET GEOMETRIC
TOLERANCING PER:
TOLERANCES:
FRACTIONAL
ANGULAR: MACH BEND
TWO PLACE DECIMAL
THREE PLACE DECIMAL
APPLICATION
USED ONNEXT ASSY
PROHIBITED.
5 4 3 2 1

35.00
11.50
11.50
0.60
11.46
11.41
11.33
4.20
4.288.00
36.70
Attachment 7
+-0.005"
This design cannot be plastic machined, however an example of parameters
are shown here.
Shelf 4
SHEET 1 OF 1
SCALE: 1:10 WEIGHT:
REVDWG. NO.
A
SIZE
TITLE:
NAME DATE
COMMENTS:
Q.A.
MFG APPR.
ENG APPR.
CHECKED
DRAWN
FINISH
MATERIAL
INTERPRET GEOMETRIC
TOLERANCING PER:
TOLERANCES:
FRACTIONAL
ANGULAR: MACH BEND
TWO PLACE DECIMAL
THREE PLACE DECIMAL
APPLICATION
USED ONNEXT ASSY
PROHIBITED.
5 4 3 2 1

3D Printed Conceptual Prototype Summary
Team PolymerWorks
Advisors: Dr. Gipson and Dr. Prins
Team members:
Mick Blackwell, Ben Condro, Mark Dufresne, Brenton Lester, and Matt Lewis

Page 2 of 3

Overview
In order to demonstrate practicality for the proposed design (displayed below in Figure 1), a 3D
prototype was fabricated using the MakerBot Replicator 2 (MR2).
Figure 1. The selected design for shelving unit fabrication. For a complete description of
parameters, refer to Attachment 6 and 7 within the SUCP documentation.
Note the documentation and thought process to conceive the concept above is shown in the
SUCP.
Process
The Makerbot Replicator 2 was made available through the in-house 3D Printing Lab. According
to the Lab-Ops, the MR2 can print 3D components up to Length = 11”, Width = 6”, and Height =
6”. Material used for printing components was PLA (poly-lactic acid). Furthermore, the
individual components of the shelf were printed in order to better replicate the actual system.
Thus, a total of five components were printed including: four supports and one shelf. The scaling
ratio was determine based on the largest parameter of the shelving system to ensure the largest
model would be created. The largest parameter of the shelving system was the required shelf
length of 45”.
Simple math yields the maximum scaling ratio stated below.
0.244 0.24 (Eq. 1)
Where was the length of the maker bot printing tray and was the length of the shelf.
As shown in Eq. 1, a printing ratio of 0.24 was derived and used for all components to obtain
appropriate interfacing during assembly. Each shelving support was printed at a rate of one
support a session due to recommendations from Lab-Ops. Figure 2 below displays the shelf
being printed.

Page 3 of 3

Figure 2. The shelf being 3D printed on the MR2.
Note nearly the maximum length of the printing tray was utilized during printing as shown in
Figure 2. Furthermore, the shelf was printed support face down in order for the print to not
require any supporting material.
Results
The 3D printing techniques utilized allowed for an appropriate demonstration of shelf
practicality. Figure 3 below displays the assembled shelving system.
Figure 3. The shelving system used for demonstrative purposes.
Note the shelving unit was attached to a metal brace only for display.
Future work involves producing a 1:1 scale ratio shelving system to fully demonstrate feasibility.

Assembly Instructions
Team PolymerWorks
Team members:

Page 2 of 7

The following documentation provides a step-by-step tabulated and figurative assembly process.
Assembly begins with acquiring needed tools. The consumer, before purchase, would need to
read the packaging of the shelving unit to find the stud spacing requirement of 16”. If the
consumer does not live in a home constructed using the 16” stud spacing convention, then the
consumer cannot properly mount the 16” support-span shelving model. Hereafter, the actual
assembly instruction template will begin (Text enlarged to portray actual assembly text).
Congratulations on your purchase of the PolymerWorks Shelving System! We
appreciate your business and we will guide you through the installation process in
a timely fashion.
In order to begin the assembly of your shelving unit, please acquire the following
tools.
1. One Stud Finder
2. One Level
3. One Drill with Appropriate Drill Bit for a #10 Screw
4. One Tape Measure
A general overview of the shelving process is shown below and figurative
instructions follow.

Page 3 of 7

Step 1: Locate the wall studs using the required stud finder. Be sure the studs are
located 16” apart as shown in the figure below.
Step 2: Mark the stud located farthest left. This will be the stud used to mount the
first support.

Page 4 of 7

Step 3: Drill two screw holes into the wall stud spaced 1.50” apart vertically using
the required tape measure, drill, and standard drill bit for a #10 screw.
Step 4: Drill two more screw holes (using the same drill bit as before) 16” to the
right (horizontally) of the screw holes drilled in Step 3.

Page 5 of 7

Step 5: Drill two more screw holes (using the same drill bit as before) 16” to the
right (horizontally) of the screw holes drilled in Step 4.
Step 6: Insert the screw and washer combination included in the packaging into the
supports as shown below. Screw the screws into the previously drilled holes until
all three supports are mounted.

Page 6 of 7

Step 7: Lay the shelf onto the supports in the orientation shown below. Be shown
supports rest in the slots on the Bottom-Side of the shelf.
Final Step: Once the shelving unit has been assembled, use the required level to
check that the shelf is level. If the shelf is level, then you have successfully
assembled your new PolymerWorks Shelving System.

Page 7 of 7

Disclaimer: PolymerWorks is not responsible for any injuries or product
malfunctions due to improper installation. PolymerWorks is also not
responsible for any injuries acquired when using required equipment.
PolymerWorks recommends professional installation when the consumer is
unsure of how to assemble the shelving system. As stated on the packaging,
the maximum weight supported by the shelving unit is 60 pounds. Product
failure may occur if the weight exceeds the recommended maximum limit of
60 pounds. If bending can be seen while examining the shelf or supports,
consider removing all supported objects and check the assembly to be sure the
shelving system was properly assembled.

Bill of Materials
Team PolymerWorks
Team members:

Page 2 of 2

Overview
In order to test different material properties, samples were bought through select manufactures.
The team budget was 100USD and the samples were purchased through Mr. John Wild of the
James Madison Engineering Department.
Bill of Materials
Materials were purchased through US Plastics and McMaster. The list of materials purchased
was separated by manufacturer and is shown below in Table 1.
US Plastics
ROD
Stock 3/8" Diameter Quantity
Price,
USD
Total,
USD
PC (Clear) 2.25 USD/ft 8 18 29.72
HDPE 5.84
USD/
8ft 1 5.84
PP 5.88
USD/
8ft 1 5.88
McMaster
ROD
Stock 1/4" Diameter Quantity
Price,
USD
Total,
USD
PC (Clear) 1.22 USD/ft 8 9.76 21.84
HDPE 0.67 USD/ ft 8 5.36 Sum
PP 0.84 USD/ft 8 6.72 51.56
Thus, team PolymerWorks stayed within the 100USD budget during the project timeline.

Statistical Analysis of Polycarbonate and
Copper
Submitted to:

Dr. Kyle Gipson

Prepared by:
Mick Blackwell
Ben Condro
Mark Dufresne
Brenton Lester
Matthew Lewis

1.0 Introduction
The materials polycarbonate and copper were mechanically tested in order to statistically prove that the
two materials were different. The mechanical test performed was a three‐point bend test that required
the use of an Instron machine. The flexural strength of each material was the property calculated in order
to determine that the two materials were different. A total of 60 trials were performed during this test;
30 three‐point bend tests for copper and 30 three‐point bend tests for polycarbonate. This number was
used in order to statistically prove with a 95% confidence that the two materials were different.
1.1 Scope
These stated tests and calculations were performed in order to statistically prove that the two chosen
materials are different. It is known that polycarbonate and copper are not the same material, but
statistical analysis was needed in order to prove with 95% that the two materials belong in different
families. By researching known flexural strengths values using CES ® software, each material tested was
comparatively quantified according to standard and known flexural strength. This helped to prove that
the procedure used and data obtained was accurate. The values obtained in this testing were entirely
quantitative and included no qualitative observations. The experiment took place in a laboratory where
an Instron machine is located.
1.2 Significance and Use
The outcomes of these experiments can in be used in order to statistically show that polycarbonate and
copper do not belong in the same material family. The three‐point bend tests can also be used to further
investigate the flexural strength of both polycarbonate and copper. Although these tests have already
been performed, the tests that were run can better indicate with statistical accuracy the flexural strength
of each material.
1.3 Apparatus
As mentioned, the apparatus used for the three‐point bend test was the Instron machine. This machine
induces a point load on a specimen that sits atop two supports. The supports used for this test were 2
inches apart and the load was place directly in the middle of the two supports. Below, Figure 1.3.1 displays
a schematic of the test performed.

Figure 1.3.1‐‐Schematic of three‐point bend test
As seen in Figure 1.3.1 the specimen was atop two supports that were 2 inches apart from one another.
The load was then placed in the middle of the supports as well as in the middle of the specimen and the
Instron machine put increasing pressure on the specimen until the point at which the specimen broke or
was bent beyond repair.

2.0 Three‐point Bend Testing
2.1 Test Specifications and Procedure
The testing procedures to determine the flexural strength of both the copper and polycarbonate followed
the steps of ASTM D790 – Standard Test Methods for Flexural Properties of Unreinforced and Reinforced
Plastics. The steps within this ASTM test were the exact same for the three‐point bend testing of metals.
The only difference within this testing standard is that it is recommended that a four‐point bend test be
run for materials that do not fail by the maximum strain.
This standard includes taking a specimen that is roughly, but no less than, 2 inches in length and placing
it atop the supports. Refer back to Figure 1.3.1 for the schematic of the setup. The load arm was then
touched to the specimen and the “Balance Load” tab was pushed on the Instron control panel. Once the
load was balanced the “Start Test” tab on the control interface was pushed in order to begin the test. The
Instron placed would then place an increasing load (pressure or force) on the specimen until it failed.
Failure took place when the specimen broke or was deformed beyond repair.
The data obtained during testing was stored on an accompanying computer using BlueHill Software and
then later transferred to a personal computer for data analysis.

Specimen

3.0 Tests Results
3.1 Flexural Strength and Statistical Analysis Results
After the testing was completed, the flexural strength of each trial was calculated. Table 3.1.1 describes
the average flexural strength for polycarbonate and copper along with the statistical data calculated for
the trials. A total of 30 trials were performed for each material family resulting in 60 trials overall. The
value of 30 was chosen for the trial amount because that it the minimum amount needed in order to
calculate statistical values. To view data for all 60 trials refer to the Appendix in sections 5.1 and 5.2.
Note that the determination for these values can be found in section 3.2 below.

Table 3.1.1: Summary of average flexural strength and calculated statistical values

The above table summarizes the average flexural strength of copper and polycarbonate calculated from
the three‐point bend test. The statistical values calculated from the 60 trials are also displayed. These
values were calculated using a 95% confidence interval. It can be seen that copper has a higher average
flexural strength than polycarbonate. One may assume from the average values that they are different,
but statistical analysis must first be performed in order to make that statement. To better illustrate the
results described above, the average flexural strength of each material along with their margins of error
were inserted into a bar graph. This is shown in Figure 3.1.1 below.

Figure 3.1.1: Bar graph of average flexural strength for copper and polycarbonate along with error bars
and display of the dmin value.

From the above data, the following determinations can be drawn:
1) Copper has a higher flexural strength than polycarbonate
2) With 95% confidence it can be determined that copper and polycarbonate are statistically
different. This can be stated because the average difference between the flexural strength of
copper and polycarbonate is greater than the calculated dmin value.

3.2 Analysis of Test Data
To calculate the flexural strength from the obtained data, the following equation was utilized:
(3.2.1)
where:
Ff = max load applied to specimen during trial,
L = span length (for these tests it was 2 inches),
R = radius of test specimen.

The average flexural strength was calculated using the following equation:

∑
(3.2.2)
where:
53171
18443
0
10000
20000
30000
40000
50000
60000
Flexural Stress (psi)
Copper
Polycarbonate
95% 1318 psi

n = the number of trials performed.
The critical t value (tcrit) was determined using the degrees of freedom (DF) and Student’s t‐value
distribution table. The DF value was calculated using the equation below:
1 (3.2.3)
where n is the same variable as in Equation 3.2.2. Next, the standard deviation was calculated using
Equation 3.3.4 below:

∑ ̅
(3.2.4)
where:
= the flexural strength of that particular trial,
̅ = average flexural strength.

The margin of error was calculated using the equation below:

√
   (3.2.5)
In order to calculate the dmin value, an intermediate variable had to be calculated. This is the sp value which
was calculated using Equation 3.2.6 below:
           (3.2.6)
where:
s1 = the standard deviation of the copper trials,
s2 = the standard deviation of the polycarbonate trials.

Last, dmin was calculated using the equation below:
∗ ∗ (3.2.7)
4.0 Summary
Using ASTM D790 – Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics,
it can be concluded with 95% confidence that polycarbonate and copper are statistically different in
regards to flexural strength. After the 60 trials were performed (30 trials for polycarbonate and 30 trials
for copper), the test results showed that the average difference between the two materials was 34,727
psi which is much greater than the calculated dmin value of 1,318 psi. This proves that the two materials
tested are statistically different.

5.0 Appendix
5.1 Flexural Strength of Copper
The flexural strength calculated for each copper trial is described in the table below.
Table 5.1.1: Flexural strength for the 30 trials of copper

5.2 Flexural Strength of Polycarbonate
The flexural strength calculated for each polycarbonate trial is described in the table below.
Table 5.2.1: Flexural strength for the 30 trials of polycarbonate

Mechanical Analysis of Polypropylene,
Polycarbonate, and Polyethylene
Submitted to:
Dr. Kyle Gipson
Prepared by:
Mick Blackwell
Ben Condro
Mark Dufresne
Brenton Lester
Matthew Lewis

of 6
1.0 Introduction
The polymers polypropylene, polycarbonate, and polyethylene will be mechanically tested in order to
compare experimental mechanical properties to mechanical values found using CES Edupack 2013
software (CES) as well as compare all three polymers to one another. The mechanical test to be
performed is a three-point bend test that makes use of an Instron 5966 machine.
1.1 Scope
The mechanical testing on the above polymers quantitatively describes mechanical properties of each
polymer. The test method being performed is a three-point bend test. From this test the flexural
strength of each polymer can be determined. Through finding the flexural strength experimentally, a
comparison can be made between polymers and also against the accepted values found using CES
Edupack 2013 software. The testing was performed on an Instron 5966 machine under laboratory
settings.
1.2 Significance and Use
The outcomes of this experiment can be used to compare the flexural strength of polypropylene,
polycarbonate, and polyethylene. The values obtained can also be used to compare mechanical
properties found through experimental analysis to those listed in CES as accepted values. The tests will
better indicate as to what flexural strength the polymers can handle.
1.3 Apparatus
The three-point bend test was performed using an Instron 5966 machine. This machine has an accessory
which allows for three-point bend testing where a material sample rests across two supports. The
Instron 5966 has a load arm which applies a force on the material at the mid-span of the supports.
Below, a schematic of the setup can be seen in Figure 1.3.1.
Figure 1.3.1--Schematic of three-point bend test
As seen in Figure 1.3.1 the material sample sets atop the two supports. The load arm applies a force
until the sample broke or ruptured on the outer surface.
Material
Sample

of 6
2.0 Three-point Bend Testing
2.1 Test Specifications and Procedure
The three-point bend testing performed was in accordance with ASTM D790, Standard Test Methods for
Flexural Properties of Unreinforced and Reinforced Plastics, procedure A. This testing procedure includes
using a support span of two inches as well as use supports and a load arm that has a cylindrical surface.
Note that ASTM D790 allows for materials that have been cut from sheets, plates, or molded shapes, or
may be molded to the desired finished dimensions. The procedure also indicates that a minimum of five
trials must be run on each material.
The procedure of testing on the Instron 5966 machine is as follows. The Instron 5966 machine was
turned on in addition to the computer connected with it. On the computer, BlueHill software was
initiated in order to use the testing apparatus. The polypropylene, polycarbonate, and polyethylene
samples were measured and cut to a length of approximately (but no less than) two inches. These pieces
were placed onto the center of the support spans. The load arm was lowered until first contact with the
sample was made and then the load and extension of the Instron 5966 were both balanced. The “Start
Test” button was pressed to initiate the machine where the load arm was lowered (applying a force to
the sample) until the sample failed or ruptured on the outer surface. Once the test was complete, a new
sample was cut and the above steps repeated.
The BlueHill software recorded the applied load and the downward extension of the load arm. This data
was saved and transferred to a personal computer so that it may analyzed further.
For reference, a picture of the testing apparatus can be seen blow in Figure 2.1.1.
Figure 2.1.1: Testing apparatus

of 6
3.0 Tests Results
3.1 Flexural Strength
The data obtained from testing was used to calculate the flexural strength of each sample. Five tests
were performed on each type of polymer so that a total of fifteen tests took place. The data from all
fifteen tests in addition to the average flexural strength for each polymer can be found below in Tables
3.1.1, 3.1.2, and 3.1.3. Note that the derivations of flexural strength can be found below in section 3.2.
Table 3.1.1: Polypropylene flexural strength properties
Polypropylene
Specimen # Flexural Strength, psi
1 14947.8
2 14987.8
3 14915.9
4 14947.3
5 14799.2
Average: 14919.6
Table 3.1.2: Polycarbonate flexural strength properties
Polycarbonate
1 21972.1
2 21838.0
3 21915.7
4 21889.5
5 21777.0
Average: 21878.4
Table 3.1.3: Polyethylene flexural strength properties
Polyethylene
1 10989.7
2 11025.1
3 11023.5
4 10996.9
5 11042.0
Average: 11015.4

of 6
The above tables summarize the flexural strength of each polymer from testing. In order to compare
these values to the accepted ones in CES, Table 3.1.4 below shows both the average values from
experimental testing and those found using CES. Note that CES does not list flexural strength, but
flexural strength can be equated to the lower of tensile or compression strength and as such the values
below represent the average of the range given for the lower of tensile or compression strength.
Table 3.1.4: Summary of Flexural Strength
Flexural Strength, Psi
Material: Experimental CES
Polypropylene 14919.6 5000
Polycarbonate 21878.4 9600
Polyethylene 11015.4 3745
The above table summarizes both the flexural strength from the experiment as well as the flexural
strength obtained from CES. Using this information the following conclusions may be formed:
1) The experimental flexural strength values do not represent the accepted values
from CES; however the hierarchy among the three polymers is the same.
2) Polycarbonate is shown to have a larger flexural strength than polypropylene and
polyethylene.
3.2 Analysis of Test Data
To calculate the flexural strength from the obtained data, the following equation was utilized:
𝐹𝑙𝑒𝑥𝑢𝑟𝑎𝑙 𝑆𝑡𝑟𝑎𝑖𝑛 = 𝜎𝑓𝑠 =
𝐹 𝑓 𝐿
𝜋𝑅3 (3.2.1)
Where sigma represents the flexural stress in psi (lbf/in2
), Ff is the force load (lbf) applied to the material,
L is the gauge length or length of the testing specimen (in), and R is the radius of the polymer rod. Note
that the flexural strength is the max flexural strain achieved while testing.
4.0 Summary
Using ASTM D790, Standard Test Methods for Flexural Properties of Unreinforced and Reinforced
Plastics, procedure A the flexural strength amongst different materials can be compared. It was found
that polycarbonate has a higher flexural strength at 21878.4 psi than polypropylene or polyethylene at
14919.6 psi and 11015.4 psi respectively. These experimental values did not agree with the accepted
values found using CES Edupack 2013 software. The experimental values were larger at 14919.6 psi,
21878.4 psi, and 11015.4 psi for polypropylene, polycarbonate, and polyethylene respectively while in
CES values (respectively) were found to be 5000 psi, 9600 psi, and 3745 psi.

of 6
5.0 References
1. ASTM Standard D790, 2002, “Standard Test Methods for Flexural Properties of Unreinforced
and Reinforced Plastics,” ASMT International, West Conshohocken, PA, 2002, DOI: 10.1520/D0790-10,
www.astm.org.

Chemical Resistance Testing in
accordance with ATSM D543
Submitted to:
Dr. Kyle Gipson
Prepared by:
Mark Dufresne
Mick Blackwell
Ben Condro
Brenton Lester
Matt Lewis

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