Project 2 - Final Report

PROJECT 2 – FINAL REPORT
TENNIS BALL DELIVERY SYSTEM – TEAM S
KEITH CATON, BRANDON BEAUDOIN, TOMMY PERKINS, ALI
ALQURAISHI, ALROUMI ALENEZI
ME 286 – 3 MWF 11:30
NAU Design for Practice
MAY 11, 2016

Executive Summary
Over the course of the last six weeks, teams of four to five members were tasked with
creating, testing, and prototyping a tennis ball delivery system. The creation of this device was
the need to complete in a competition held by the Design for Practice team at NAU. The
contest entailed transporting a tennis ball from a starting location to a one of several targets
laid out in a field. By using the techniques learned about the Design Process, Team S, created a
ballista, figure 1, that met the requirements of the competition but did not exceed them. The
team learned the value of all the processed used and how original design works not only in the
education environment, but the real world. The course of concept generation, selecting the best
concept, prototyping and testing are detailed below. The results of the competition and a post-
mortem are located at the end of this report.

Table of Contents
Introduction...................................................................................................................................................................................1
The Design Process ...................................................................................................................................................................1
Clarify the Problem...............................................................................................................................................................1
Concept Development ........................................................................................................................................................2
Embodiment of Design .......................................................................................................................................................3
Detailed Design...........................................................................................................................................................................4
Design for Manufacturing and Assembly ..................................................................................................................4
Failure Models and Effects Analysis .............................................................................................................................6
Costing Analysis for Mass Production.........................................................................................................................7
Beta Prototype.............................................................................................................................................................................8
Bill of Materials .......................................................................................................................................................................8
Assembly Drawings...............................................................................................................................................................8
Conclusion .....................................................................................................................................................................................9
Post Mortem ............................................................................................................................................................................9
Contributors to project success ..............................................................................................................................10
Opportunities and Areas for Improvement.......................................................................................................10
Post Mortem Conclusion............................................................................................................................................11
Appendix A – The Design Process ..................................................................................................................................12
Appendix B – Detail Design ...............................................................................................................................................20
Appendix C – Beta Prototype............................................................................................................................................24

Introduction
The process of designing concepts, selecting the best concept and prototyping a working
device is a long process that the team has been working on for the last six weeks. During that
time, the use of concept generation techniques, system models, and prototyping techniques
were used. The focus of this project was to practice the process of original design and the
entire design process. This is a valuable process that all engineers use to solve the problems
that people face. The teams were tasked with creating a device that would transport a tennis
ball to one of several targets. The project was left inherently open ended, other than some
safety and organizational requirements, the bulk of which are described later in the report. With
the problem set before the class and the day of competition coming, the team set out to design,
analyze, test and prototype a device to meet these goals. The team gained valuable knowledge
and experience of the design process; the results of the last six week are detailed in the sections
below.
The Design Process
The design process for this project was a long process, which encompassed several
weeks of work. The process is broken into three parts, clarifying the problem, concept
development and embodiment. By using techniques learned in class, the team was able to
develop 15 concepts, narrow down the concepts to the best idea and finally using prototyping,
create a working device that could be demonstrated. The first step of the design process is to
identify the problem and clarify how the device needs to perform.
Clarify the Problem
For this project the problem was simple, transport a tennis ball to a target. The actual
way that the ball could be moved is the real challenge. Initially the constraints and requirements
were left broad and unknown as to not hinder the concept generation process. As the project
progress, the precise rules and requirements for the competition were made available. The rules
for the competition required that the team members had to remain within the starting area
when any tennis ball was in action or the device was in an “active” state. The device also had to
be built with simple materials found from home improvement or hobby stores and all

manufacturing had to be done either by the students or at the machine shop located on
campus.
To help clarify the problem, the team developed several customer requirements for the
device. With the team being the customer this process was simple, requiring a team meeting to
determine what is important for the design. The result of this meeting can be found in table 1,
located below.
Table 1 Customer Requirements
1-5 Scoring Keith Alroumi Ali Tommy Brandon Total Rank Weight
Distance 5 5 5 5 5 25 1 5
Accuracy 5 4 4 5 5 23 2 4.6
Durability/Reliability 3 4 5 3 4 19 3 3.8
Cost 3 3 4 3 3 16 4 3.2
Refresh Time 2 3 4 1 3 13 5 2.6
Ease of Setup 2 2 2 3 3 12 6 2.4
The requirements were ranked by the team members and then the rank is correlated to the
weight to determine which customer requirement is the most important.
Another technique used to clarify the problem was the creation of a functional model.
The use of functional models is an important tool for clarifying the problem as it lays out the
exact functions that the devices is needed to perform. For this project, the team developed a
functional model for a ballista that would later become a basis for the alpha and beta prototype,
appendix A, figure 1. By creating this functional model, the team gained better understanding
of what is required for the competition and what systems would be the most difficult to
implement. With the rules known and an understanding of the systems and requirements for
the device, the team started the concept generation process.
Concept Development
Once the problem was identified, the team started the process of developing concepts.
The techniques for concept development used were, c-sketches, bio-inspired design, and a
morph matrix. By using these techniques, the team developed 15 possible ideas that could
solve this problem. The morph matrix used for this project is detailed in appendix A, figure 2
and the sketches that came from it are found in appendix A, figures 3 and 4. The sketches
included a reeling in cart that used a suction cup to grab onto the target. Once locked in, the

cart would pull its self to the target then release all the tennis balls onto it in once single
motion. The other concept developed from this method was a laser guided aerial drone that
would be able to lock onto the target, transport the tennis balls and then deliver them all at one
time. These design were a product of combining the ideas from the morph matrix into a full
blown concept. These concepts proved to be too complicated to implement, this was confirmed
using concept narrowing techniques.
To narrow down the 15 created concepts, the team used several techniques, the first of
which was a Pugh Chart. The Pugh chart is a process of choosing a base line or datum, which
the rest of the concepts are compared to. The concepts are compared to the datum by the
customer requirements and are given either a +1, 0 or -1 if they outperform, are equal
performance or perform poorer than the base line. The results of the Pugh Chart can be found
in appendix A, table 1. The results of the table were then added up to determine the top five
designs that were then put into a decision matrix. The decision matrix takes the best designs
and put them through a more rigorous analysis. Each design is compared to the customer
requirements again, this time they are given a score from one to five. The scores in each
category is then weighted against each CR, and then totaled up. The two designs with the
highest weighted score move on to the final concept narrowing step, system models.
System models are equations used to determine the requirements needed to achieve a
certain goal. For this project, the main goal was distance the tennis ball could travel. For this,
the team developed a system model for determining the amount of energy needed to achieve a
certain speed to travel needed to reach the desired distance of 150 feet. As seen in appendix A,
figure 5, the back of the envelope calculations showed the peak height, the flight time and
velocity of the ball. This information was used to help determine the amount of potential
energy required. This helped determine the amount of bungee cord that would be needed or
the amount of air pressure needed. With an understanding of what would be required for the
device and how it should preform, the next step of the design process is embodiment.
Embodiment of Design
Embodiment of the design is the process of developing proof of concepts and
prototypes that demonstrate the functions of the device. The team created two prototypes and
two proofs of concept. The original design of the device was a traditional ballista. Using a
cradle on a track that would hold the tennis ball and bungee cord attached to the cradle would

provide the acceleration of the cradle which would then transfer the energy to the tennis ball.
The proof of concept for this design was the track to cradle system. The cradle, as shown in
appendix A, figure 6, shows the original idea for how the cradle would interact with the rest of
the device. The original design called for metal plates to run between the two slots in the wood,
this would allow the wood to follow a track and move the tennis ball forward to a point where
when stopped would transfer all the kinetic energy to the ball. This design was disregarded for
a simpler solution of using a tube with a slot cut out. The slot allowed the bungee cord to be
threaded through it which was ran behind the ball. When the cord was pulled back, it was
stretched which built up elastic energy, this energy was released when the cable was released
and transferred to the ball. There was one major flaw with this design, the cable would whip
around the ball and fail to accelerate it forward, and this problem was fixed in the beta
prototype which is detailed later in the report.
The end result of the alpha prototype is located in appendix A, figure 7. As mentioned
above, the track was replaced with a PVC pipe that would act as the barrel. The alpha was
constructed of mostly red wood which was cheap and readily available. The bungee cord was
simple flat cord purchased from The Home Depot and cut to length. This design was later
retrofitted and improved to become the beta prototype. With the beta prototype finished, the
team began work on the final step of the Design Process, Detailed Design.
Detailed Design
The final step of the Design Process is Detailed Design. This step is only an analysis for
the scope of this project, in which the team determines what would be required for actual
manufacturing. The three process that were analyzed are, Design for Manufacturing, Failure
Modes and Effects Analysis and a Cost Analysis. The details of these processes are detailed in
the sections below.
Design for Manufacturing and Assembly
During the manufacturing of the Beta Prototype by hand, the team realized quite a few
issues that could be addressed when improving the device for its shelf product stages. The first
issue deals with the main structure of the device. Making the entire device out of wood was
definitely cost efficient, but lacked in quite a few ways. With the correct resources, the best idea

would to be to reconstruct the out of low carbon steel for a few reasons. First low carbon steel
is fairly sturdy, but is also inexpensive. This will keep strengthening, seeing as there are a great
deal of moment forces accruing, and keep cost low. Also low carbon steel is denser than metals
like magnesium and aluminum. This would add weight to the base allowing for an improved
shot. Also, doing an injection mold or a cut out shape would become more feasible. Either of
the two would turn a four piece base with fasteners into a single structure. This not only
decreases the part count but also regains the strength and stability lost in using fasteners.
The next issue comes in the general form of fasteners used to bind pieces together. The
team feels it best to replace screws with rivets. Rivets are not only safer due to their edges, they
are also more reliable than screws and better utilized in metal. Bolts would likely be the most
reliable for holding the structure together, however they take up a gr eat deal more space. And
would add more weight in areas where such would be undesirable. Rivets, are likely to become
unnoticeable and maintain a uniform look to the device. Rivets can also be placed using
machine which lowers the handling time of the device.
The team would also like to see a change in the vertical supports. Currently, the idea
would be to exchange the wood for aluminum with an inner diameter to keep the weight low,
the cost low, and the inertia high. The vertical supports must not retain the same amount of
weight as the base in order to limit their ability to create a loss in stability from the forces
applied with the device is launched. Stability supports for the structures would also be more
easily applied with rivets. Having the vertical supports constructed out of aluminum would also
allow for y axial slots to be cut out of the left and right sides of each support to allow for more
ranged and possibility in the horizontal support.
Leading onto the horizontal support, already made out of low carbon steel, it would
likely be best for it to remain its current material. From what was calculated, maintaining a low
carbon steel for the horizontal support would not create a weight issue and would keep the cost
down. The beneficial alteration considered by the team would be to add threads onto either end
of the bar with butterfly nuts. One of the biggest letdowns of the device was not being able to
alter the angle as was had originally planned, and this would re-implement that possibility. The
idea is not simply to change the angle for the ability alone, being able to change the angle
would increase the accuracy and efficiency of the device as a whole.

In order to better assist the track in adjusting the horizontal bar movement, the
attachment configuration would be a necessary improvement as well. Currently the track is held
onto the horizontal support by a bungee cord. Of course this served its purpose in allowing us
to test the Beta Prototype but it would not be an efficient accommodation if the bar is able to
move. It has been considered to reconstruct the actual track out of aluminum as well to keep
the weight low, and proceed to rivet a rail track to the underside, so the horizontal support
could move freely back and forth in order to allow angle change but not up and down. When
the horizontal support is locked into a desired angle, it would no longer be able to shift or move
along the track.
Finally, the best finish to accompany the final structure would be a simple spray down of
a desired pigment or color. Seeing as a vast majority of it would be mold injected, the issue of
rough or dangerous ends would be minimized as well as the need to buff those ends. The
structure would likely only be handled in specific areas, discarding the need to smooth or round
out many of the edges. The addition of a flat paint would not only smooth out the surface faces
of the metal structure but would also give the device a non-reflective finish minimizing the light
distractions the come with metal.
Failure Models and Effects Analysis
The team developed a Failure Models and Effects Analysis to determine what areas of the
device could lead to problems with the overall performance. The result of this analysis is located
appendix B, tables 1 and 2. From this analysis the team determined that most of the failures
that could occur were from wear and tear of the device and not something that would happen
during demonstration day. The failures that were concerning were misfires. A misfire was
defined as a failure to launch the ball past 10 feet. There are several sub-functions that could
cause a misfire but the one that caused it the most on the alpha prototype was the bungee cord
whipping around the tennis ball. The use of a cradle was tested at first but that added in cradle
failure and higher chance of barrel jam. This was disregarded for a simple bar system that
would run down the barrel. The bar could not whip around the tennis ball which solved the
major issue with the alpha prototype. The bar did add a new failure of the bungee coming off
the bar or the bar twisting in the barrel. This was solved by adding washers to the bar to keep
everything in place.

The FMEA helped show what systems and parts would be a problem during
demonstration day. With this knowledge, the team devised new systems and solutions to
problems raised from the FMEA. This information ultimately helped with demonstration day but
there were still problems that arose on demonstration day. A second FMEA with the changes
from the first FMEA could have potentially brought the new failures to light.
Costing Analysis for Mass Production
Two parts the team chose to apply a costing analysis are, the Track Tube and Horizontal
Support. These items are easy to manufacture in all aspects: shape, material, size, and
manufacturing process required. In fact, both of the items analyzed could be manufactured in
multiple ways therefore; the most cost efficient method was used when considered within the
costing analysis program.
The Track Tube is made of Polyvinyl chloride (PVC) as this was not an option, the
seemingly closest material Polypropylene was chosen as the building material as it is of a similar
compound and unit cost. The only factors to be considered within the injection molding
program was the dimensions of the part to be made, and the number of parts to be made,
appendix B, figure 1. Once all of the numbers were run through the program, the cost per unit
for the Track Tube was to be set at $.40 per part when considering one million parts including
setup, tooling, and labor costs of $35/hr. Interestingly enough, the number of mold cavities
would only be one but the “intermediate” part complexity offered the lowest number of mold
cavities, five, as a result this option was selected.
The other part selected to analyze the cost per part if manufactured is the Horizontal
Support. This part, in essence, is simply a long thin cylindrical piece of metal. As a result, the
manufacturing technique selected was milling from a bar of aluminum. The raw aluminum bar of
dimensions .375 in2x24in is then milled down to a .375in diameter rod of length 24in.
Calculations can be done to find the ratio of volume before and after to get a ratio of .80, or
only 20% of the original material is milled off to reveal the final product. Since the part being
manufactured is a cylinder, the number of surfaces is three considering each face and the curved
surface. Considering each of these factors the total cost per unit came out to be $3.05/part, as
shown in appendix B, figure 2. During the Detailed Design process, the team also worked on
the beta prototype, which is the device that would be used on competition day.

Beta Prototype
The beta prototype is a prototype that is designed and functions in the way the final
assembly product would be work but uses special manufacturing techniques. This prototype is
used to demonstrate how the final product will work and is the device used for the competition.
For the beta prototype, the teams were required to develop a bill of materials and assembly
drawings for the device. The details of those reports are located below.
Bill of Materials
The Beta Prototype developed by the team resulted in fairly cost effective results. After
three days of cost comparisons, research and team considerations, the team was able to make a
decision on the most feasible materials to purchase. Utilized materials, and proposed materials
still changed throughout the construction in order to accommodate for both, a low cost and
more predictable launch patterns. The dominant material was red wood at two dollars and 77
cents for every 8 ft with a 2 inch by 2 inch cross section. By collecting a vast amount of red
wood and utilizing that in the majority of the production, the final cost was able to be
minimized. By creating the base, track and major supports out of red wood, it was possible to
construct over 60 percent of the final structure for just under 7 dollars. Wood structures were
then supported by metal brackets, screws, a hinge, a metal rod or alternative wood based on the
circumstances. Through thorough measurements, the device was also able to stay within the
size requirements and remain light enough for single person transportation. The most expensive
piece if the device was the PVC pipe, used as the track for the launching mechanism, at five
dollars and 79 cents. Unfortunately there is not much of an alternative as far in Polyvinyl
Chloride tubing was concerned. Fortunately, only one PVC tube was required for construction.
Each of the remaining materials remained below the three dollar mark. The final cost of the Beta
Prototype came out to 25 dollars and six cents, 20 percent of the cost limit of 125 dollars.
Assembly Drawings
The assembly drawing for this project shows the complexity of even a simple device such
as the ballista that was prototyped. The drawing, located in appendix C, figure 1, shows the
device in an unexploded view with a simple break down of the materials and the locations of
those materials. Doing a drawing of the device is important because it often shows how the
information of the device such as dimensions and part placement are expressed for other

engineers and manufacturing companies to recreate the device. The time spent creating the
drawing also helped show the inherent problems with the design and allows for theoretical
changes to be made that could be implemented in future iterations. With the drawings and bill
of materials completed the beta prototype was ready for competition day.
Conclusion
The device that was created to compete on demonstration day met the expectations of
the team. While team S scored lowest from section three, it still met the requirements of the
design and the goals set out by the team. The biggest problem faced demonstration day was
the washers that held the bungee cord in place on the bar broke after the second firing of the
device. This made it so time was spent resetting the bar and unjamming the barrel before
another shot could be fired. As mentioned in the FMEA section, more failure analysis could have
brought this problem to light and the team would have been able to rectify the problem before
competition day. Overall the team reacted to the best of our abilities. We worked out the
problem of the bar and set-up runners to retrieve the tennis balls, with the rest of the members
assigned to firing and “repairing” the device. After the first round, the team looked to fixing the
bar getting jammed in the barrel, with limited resources and time, the team decided that
wrapping the bungee cord around the bar tighter would make for a stable connection. This
solution mostly worked, the team was able to get in more fires the second round than the first
but the issue of aim was still apparent.
The weather conditions of the day had some effect on the performance of the tennis
ball. The wind played a factor in the devices ability to hit the targets but the largest problem
was inconsistent firing power. Each fire was done more rapid succession than with calculated
thought, with each pull being too hard or too soft, thus missing the desired target. The device
still preformed as expected. There were no misfires, and the goals set out by the team were
met. Overall the device served its purpose and the design process taught the team much about
what it is like to be an engineer.
Post Mortem
The overall success of the device relied on the team and the work they put in. While the
device did not meet the highest goals set out by the team, it did meet what was needed and

expected. The post mortem is broken into two sections that will detail the major contributors
to the project and the areas of improvement for future iterations of the project.
Contributors to project success
The entire team contributed to the success of this project. Each member took on
different aspects of the project and fulfilled them to the highest of their abilities. With all the
work done by the team, the project was a success at the lowest level of success. As stated
before, the device met the goals of the project but did not exceed them. The most positive
parts of the project was the actual competition day. The team worked well together and tried
their best to score the highest the team could. The development time and cost for the ballista
device were low. The device did not get close to the cost cap and the total time spent building
it was around 10 hours. Major contributors to the build were Tommy who cut most of the
wood, Brandon who did the metal work and Roumi who provided a place to work and store
everything. The entire team contributed to the write ups required by this project, but several
team members excelled with the write ups. Keith took on formatting and report design, he also
compiled all the work done by the other members. Tommy was a major contributor always
completing his work on time and willing to take on sections that still needed to be worked on
and Brandon always edited the memos and reports. This break down of duties for the write ups
proved to be a very positive system that worked well. The other areas of this project were
difficult to meet and proved challenging for the team to complete.
Opportunities and Areas for Improvement
While this was a good project for teaching the design process and the systems used,
many of the techniques used were time consuming and challenging. The concept generation
techniques, while important and taught the team many different ways of developing ideas, was a
very long and drawn out process that was difficult for some come up with imaginative ideas.
The process broke down into creating ideas that were not feasible at all and did not provide
much help to the actual device that was designed. The biggest problem faced by the team was
communication. The use of group text messages and emails worked nicely but there were
problems with members not responding and the root problem of emails with people either not
getting the mail or just not opening it. Further projects could be improved by using calendars
and computer based meeting systems to make team meetings easier. The Gantt Chart helped at
first but the original plan set-up by it was soon disregarded and tasks were finished on the fly

instead. This made some things very difficult to accomplish and better following of set timelines
would do much to improve team efficiency.
Post Mortem Conclusion
The project still met the goals set out by the Design for Practice staff and the
requirements of Abet accreditation. The team learned the value of performing failure analysis,
cost analysis, the use of system models and the many different forms of concept generation and
concept selection. The prototyping phase of this project is the only part that was truly difficult
and required skills that several of the team member didn’t have. While a device as made, it is
apparent that skills from other team members allowed them to produce a better prototype. This
cross of skills is important for engineering and allowed for very creative and interesting designs
that show that one concept, while it may work in theory, in reality the use of prototypes and
proof of concepts shows what is viable and what should actually be used.

Appendix A – The Design Process
Figure A - 1 Ballista Functional Model

Figure A - 2 Morph Matrix

Figure A - 3 Morph Matrix Sketch 1

Figure A - 4 Morph Matrix Design 2

Table A - 1 Pugh Chart
-1101110D-1101110
-1010111A-1-101010
10111-11T00-1-10-11
1110-1-1-1U11-1-10-11
11011-11M1100101
11-11-10-1!10011-10
443442303303323
101023201122030
24242-11012-213-13
PughChart
t

Figure A - 5 Back of Envelope Calculations
Find minimum velocity needed to Reach 150 feet.
150 feet = 45.72 meter
Max angle = 45 degrees
Xfinal = Xinitial + Vx*Time + (A*Time^2)/2
(note: no general acceleration; wind resistance will be acceleration)
Vy = Vinitial*(sin(45 degrees))
Vx = Vinitial*(cos(45 degrees))
The acceleration due to wind resistance is a negative which is equivalent to:
-(Air Density Kg/m^3)*(Drag Constant)*(Surface Area)
----------------------------------------------------------------------------------------*(Vx)^2
2 (weight)
WIth Flagstaff conditions and the average size of a tennis ball this equation becomes
- (.962Kg/m^3)*(.025)*(.014m^2)
-------------------------------------------------------------------*(Vx)^2
2(.0581)
= - .0029 * (Vinitial(cos(45 degree)))^2
The time to reach peak height and the flight time (peak height *2) were found to be described by
Vpeak = Vy + A*T
(note: y velocity at peak is zero as it changes directions
0 = Vinitial*(sin(45 degrees)) -9.81m/s^2(peak time)
Vinitial*(sin(45 degrees))
Peak Time = ------------------------------------------------------
9.81m/s^2
Flight Time = Peak Time *2
Final Displacement with other variables in terms of the Velocity is equivalent to the following
Xfinal = Vinitial(.7071)*(2)(Vinitial(.7071)/9.81)-
(.0029(Vinitial*.7071)^2)*((2)(Vinitial(.7071)/9.81)^2)/2
Or
45.72 meters = .102(Vinitial)^2 - (0.000015067)(Vinitial^4)
With this we find that the minimum velocity to reach 150 feet is 22 m/s or 50 MPH. Also we find
out that the following is true:
Vx = Vy = 15.56 m/s
Flight Time = 3.172 seconds
Peak Height = 12.334 m
Acceleration due to wind = .706 m/s^2

Figure A - 6 Proof of Concept Cradle

Figure A - 7 Alpha Prototype

Appendix B – Detail Design
Table B - 1 FMEA Part 1
ComponentName
Part#andFunctionsPotentialFailureModePotentialEffect(s)ofFailureSeverity(S)PotentialCausesandMechanismsofFailureOccurance(O)
1BaseSeperatesErracticeBehavior,potentialFailure,HealthHazard5ExcessiveForceonjoints,ManufactoringError2
1BaseTorquesLossofaim,healthHazard3Failureofsupports1
2VerticalSupportFailsUnabletoangle,lossofaim7Torque,Screwsfail3
2VerticalSupportSplitsPotentialFailure,lossofsupport6Torqueonscrews1
3TrackSupportSplitsPotentialFailure,lossofsupport6Torqueontrack,sheerforces1
4TrackHorizontalSupportSplitsPotentialFailure,lossofsupport6Torqueontrack,sheerforces1
5AngleHingebreaksUnabletoangle,lossofaim7ExcessiveTorque,ManufactoringError,Fatigue,Age1
5HingepullsoutofwoodUnabletoangle,lossofaim7StressFatigue,Woodsplits,Maxscrewyield2
5HingeRotationUnabletoangle,lossofaim7Weather,lackoflubrication,oxidation,surfaceimpurities1
7BreakofBungeeCompleteFailure,HealthHazard10FatigueStress,Distance2
8SupportBungeeFailsPotentialFailure,lossofsupport2FatigueStress1
9BarrelCracks/BreaksCompleteFailure,HealthHazard10StressFatigue,Pressure,Surpassmaxyield1
9BarrelJamFailedFire,PotentialHazard3PoorManufacturing,Bungeegettingcaught,CradlegettingCaught3
9BarrelDisattachmentCompleteFailure,HealthHazard10ScrewStress,Excessiveforce2
10SupportArmsFailUnabletoangle,lossofaim7FatigueStress,Surpassmaxforceyield5
13EyeloopbreakCompleteFailure,HealthHazard10FatigueStress,ManufactoringError,Surpassmaxyield1
13EyeloopunseatedCompleteFailure,HealthHazard10FatigueStress,ManufactoringError,Surpassmaxyield,ExcessiveTorque3
13EyeloopwoodsplitErracticeBehavior,potentialFailure4FatigueStress,ManufactoringError,Surpassmaxyield,ExcessiveTorque7
14CradleFailsFailedFire,PotentialHazard5Stress,Unevenforceapplication,roughbarrel3
EntireDeviceMisfireFailedFire,PotentialHazard8Ballfallsfromcradle,bungeegoesaroundcradle7
BallistaTeamS-KEITHCATON,BRANDONBEAUDOIN,TOMMYPERKINS,ALIALQURAISHI,ALROUMIALENEZI

Table B - 2 FMEA Part 2
Current Design Controls Test Detection (D) RPN Recommended Action
Fire Device 9 90 Add strenghting braces or replace with metal
Fire Device 8 168 Replace with Metal support
Fire Device 9 126 Mount as a slot in the base
Fire Device 9 63 Keep Hinge Lubricated
Fire Device 8 160 Regular replacement of coord
Fire Device 9 18 Replace Regularly
Fire Device 10 100 Replae with Metal barrel
Fire Device 4 36 Smooth and Lubricate Barrel
Fire Device 10 200 Add more supportive structures
Fire Device 8 80 Strenghting of material, preventaive maintence
Fire Device 8 120 Replace with Cross Bar
Fire Device 3 168 Preventative Maintence
Page No 1 of 1
FMEA Number 286-03-02-01
5/10/2016

Figure B - 1 Cost Analysis Injection Molded Plastics

Figure B - 2 Cost Analysis Machined Part

Appendix C – Beta Prototype
Table C - 1 Bill of Materials

Figure C - 1 Assembly Drawing

Project 2 - Final Report

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