- Stress is defined as the internal force per unit area within a material. It can be tensile or compressive. Common types include normal stress and shear stress.
- Strain is a measure of deformation in a material under stress. Normal strain measures changes in length while shear strain measures changes in shape.
- The allowable stress for a material is less than its failure stress to ensure safety under loads. Factor of safety is defined as the ratio of failure stress to allowable stress.
This powerpoint presentation deals mainly about bearing stress, its concept and its applications.
Members:
BARIENTOS, Lei Anne
MARTIREZ, Wilbur
MORIONES, Jan Ebenezer
NERI, Laiza Paulene
Sir Romeo Alastre - MEC32/A1
This powerpoint presentation deals mainly about bearing stress, its concept and its applications.
Members:
BARIENTOS, Lei Anne
MARTIREZ, Wilbur
MORIONES, Jan Ebenezer
NERI, Laiza Paulene
Sir Romeo Alastre - MEC32/A1
In this section the concept of stress will be introduced, and this will be applied to components that are in a state of tension, compression, and shear. Strain measurement methods will also be briefly discussed.
1. In this module we will determine the stress in a
beam caused by bending.
2. How to find the variation of the shear and
moment in these members.
3. Then once the internal moment is determined,
the maximum bending stress can be calculated.
Design aids for tension members as per revised is 800 2007eSAT Journals
Abstract The B.I.S. recently revised the new IS: 800-2007 . This is based on limit state method. This new code includes variety in elements like tension members, compression members , flexural members, combined connection, combined axial and bending design of members. The B.I.S. has yet not published any design aids based on new IS: 800-2007. For saving time in various design of structural steel section, one need to have their own computer programme or design aids or spreadsheet which is based on IS: 800-2007. In this research we have developed excel programme spreadsheet to analyze & design tension members, which will help the structural designer to save their time in designs. Also we have prepared design aids to find out the capacity on angled tension member with single row of bolts connected to the gusset plate. Keywords: Tension members, Design aids , IS:800-2007 , Analysis , Designing , Spreadsheet, Structural steel
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Honest Reviews of Tim Han LMA Course Program.pptxtimhan337
Personal development courses are widely available today, with each one promising life-changing outcomes. Tim Han’s Life Mastery Achievers (LMA) Course has drawn a lot of interest. In addition to offering my frank assessment of Success Insider’s LMA Course, this piece examines the course’s effects via a variety of Tim Han LMA course reviews and Success Insider comments.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
1. Stress and Strain
The most fundamental concepts in mechanics of material are stress and strain
Consider a prismatic bar under a axial force F (disregarding weight of bar) and
an axial force is a load directed along the axis of the member, resulting in
either tension or compression in the bar.
Stress
F F
Examples: bridge truss, connecting rods, wheel spokes and columns in buildings.
Prismatic bar: straight structural member having the same cross-sectional area A
throughout its length
Stress
2. Internal actions exposed by making imaginary cut at section m-n
F F
m
n
Continuously distributed stresses acting over entire cross section, and the axial
force, F acting at the cross section is the resultant of those stresses.
F
Resultant force
Stress has units of force per unit area and is denoted by Greek Letter σ (sigma) . In
general stresses acting on a plane may be uniform or may be vary in intensity. In
this course stresses acting on cross section assumed are uniformly distributed over
the area. Then resultant of those stress must be equal to the magnitude of the stress
times the cross-sectional area A of the bar.
Stress
3. Stress = intensity of the internal force
Generally speaking
Or symbolically,
SI units: Magnitude of stress is N/m2, called Pascal (Pa)
When bar stretched by force F, the stresses are tensile stresses
If forces are reversed than the stresses are compressive stresses
Stresses act perpendicular to the cut surface, they are also called normal stresses.
Normal stress can be either tensile or compressive
Stress
4. The bar in figure has a constant width of 35 mm and a thickness of 10 mm.
Determine The max. average normal stress in the bar when it is subjected to
the loading shown.
Examples
Determine internal normal force at section A. if rod is subject to the external
uniformly distributed loading along its length of 8KN/m
A
2m 3m
Stress
5. Rods AC and BC are used to suspend the 200-kg mass. If each rod is made of a
material for which the average normal stress can not exceed 150 MPa,
determine the minimum required diameter of each rod to the nearest mm.
Stress
6. Shear stress: If stress acts parallel or tangential to the surface of the
material.
where
τavg = Average shear stress at the section
V = Internal resultant shear force parallel to the
area
A = area at the section (or area on which it (V)
acts)
Shear stress, 𝝉 =
𝑽
𝑨
A
Stress
Greek letter τ (tau)
7. Loads are transmitted to individual members through connections
that use rivets, bolts, pins, nails, or welds
Forces applied to the bolt by the plates
These forces must be balanced
by a shear force in the bolt
This results in Shear
stress, ′𝝉’ on bolt,
𝝉 =
𝑭
𝑨
=
𝑭
𝝅𝒓 𝟐
F
F
V V=F
Single Shear
Stress
8. F
F/2 F/2
F/2=V V=F/2F
Shear stress on bolt
𝝉 =
𝑭
𝑨
=
𝑭
𝟐𝑨
Where
A is the cross sectional area of bolt
r is the radius of bolt
Double Shear
Stress
9. Bearing Stress
A normal stress that is produced by the compression of one surface against
another is called bearing stress. If the bearing stress becomes large enough then it
may deform surfaces in contact.
The bolt exerts on plate ‘A’ a force Fb equal and opposite to
the F exerted by the plate on to the bolt.
Fb represents the resultant forces distributed on the inside
surface of half cylinder of the plate.
The actual distribution of the stress is difficult to
determine. It is customary to assume that stresses are
uniformly distributed. Based on this Bearing stress can be
calculated by dividing the total bearing Force Fb by bearing
arear Ab
𝜎 𝑏 =
𝐹𝑏
𝐴 𝑏
Bearing area is projected area of the curved bearing surface
𝜎 𝑏 =
𝐹𝑏
𝑑𝑡
𝐴 𝑏 = dt
𝑤ℎ𝑒𝑟𝑒
d is diameter of bolt
t is thickness of plate A
Fb
10. Examples
Determine the average shear stress in the 20-mm diameter pin at A and the
30-mm diameter pin at B that support the beam.
Stress
11. A punch for making holes in steel plates is shown in the figure. Assume that a
punch having diameter d = 20 mm. is used to punch a hole in a 8 mm. plate, as
shown in the cross-sectional view. If a force P = 110kN is required to create the
hole, what is the average shear stress in the plate and the average compressive
stress in the punch?
Stress
12. Normal and Shear stresses on inclined sections
b
c
ϴ
A
P
2D view of the normal section
(thickness perpendicular to the
page)
2D view of the inclined section
Stress
13. The force P can be resolved into components:
Normal force N perpendicular to the inclined plane, N = P cos θ
Shear force V tangential to the inclined plane V = P sin θ
14. If we know the areas on which the forces act, we can
calculate the associated stresses.
Stress
15. A prismatic bar having cross-sectional area A=1200mm2 is compressed by an
axial load P=90KN. Determine the stress acting on an inclined section pq cut
through the bar at angle ϴ = 250
Stress
Example
16. Allowable Stress
An 80 kg lamp is supported by a single electrical copper cable of diameter d =
3.15 mm. What is the stress carried by the cable.
Example
a a
F
mg
FBD
Whether or not 80kg would be too heavy, or say 100.6MPa
stress would be too high for the wire/cable, from the safety
point of view. Indeed, stress is one of most important indicators of structural
strength.
Stress
17. When the stress (intensity of force) of an element exceeds some level, the
structure will fail. For convenience, we usually adopt allowable force or allowable
stress to measure the threshold of safety in engineering.
σ ≤ σallow
There are several reasons for this that we must take into account in engineering:
• The load for design may be different from the actual load.
• Size of structural member may not be very precise due to manufacturing and
assembly.
• Various defects in material due to manufacturing processing.
• Unknown vibrations, impact or accidental loading
To ensure the safety of a structural member it is necessary to restrict the applied
load to one that is less than the load the member can fully support.
Stress
18. One simple method to consider such uncertainties is to use a number called the
Factor of Safety, F.S. which is a ratio of failure load Ffail (found from experimental
testing) divided by the allowable Fallow
𝐹. 𝑆 =
𝐹𝑓𝑎𝑖𝑙
𝐹𝑎𝑙𝑙𝑜𝑤
If the applied load is linearly related to the stress developed in the member, as in
the case of using 𝜎 =
𝐹
𝐴
𝑎𝑛𝑑 𝜏 𝑎𝑣𝑔 =
𝑉
𝐴
, then we can define the factor of safety as a
ratio of the failure stress σfail (or to 𝜏 𝑓𝑎𝑖𝑙) to the allowable stress σallow (or 𝜏 𝑎𝑙𝑙𝑜𝑤)
𝐹. 𝑆 =
𝜎𝑓𝑎𝑖𝑙
𝜎 𝑎𝑙𝑙𝑜𝑤
𝐹. 𝑆 =
𝜏 𝑓𝑎𝑖𝑙
𝜏 𝑎𝑙𝑙𝑜𝑤
𝑂𝑅
Usually, the factor of safety is chosen to be greater than 1 in order to avoid the
potential failure.
𝐹. 𝑆 =
𝜎𝑓𝑎𝑖𝑙
𝜎 𝑎𝑙𝑙𝑜𝑤
> 1 𝐹. 𝑆 =
𝜏 𝑓𝑎𝑖𝑙
𝜏 𝑎𝑙𝑙𝑜𝑤
> 1
𝑂𝑅
19. F. S also dependent on the specific design case. For nuclear power plant, the
factor of safety for some of its components may be as high as 3. For an
aircraft design, the higher the F.S. (safer), the heavier the structure,
therefore the higher in the operational cost. So we need to balance the
safety and cost. In case of aircraft F S may be close to one to reduce the
weight of aircraft.
Example: If the maximum allowable stress for copper is σCu,allow=50MPa.
Determine the minimum size of the wire/cable from the material strength point
of view.
Obviously, the lower the allowable stress, the bigger the cable size. Stress is
an indication of structural strength and elemental size.
Stress
20. Determine the maximum vertical force P that can be applied to the bell crank so that the
average normal stress developed in the 10-mm diameter rod CD, and the average shear
stress developed in the 6-mm diameter double sheared pin B not exceed 175 MPa and 75
MPa.
Example
Stress
21. Strain
When a force is applied to a body, it will tend to change its shape and size, in
other words the body is deformed. Strain is intensity of deformation.
Normal strain (ε): measures the change in size (elongation/contraction)
Normal Strain is a dimensionless quantity. Sometimes it is stated in terms of a ratio of
length units. Usually, for most engineering applications ε is very small, so measurements of
strain are in micrometers per meter (μm/m).
22. Shear Strain
Measures the change in shape (angle formed by the sides of a body)
θ = the angle in the deformed
state between the two initially
orthogonal reference lines
Shear strain: γ = π/ 2 -θ’ (in radians)
The shear strain is positive when the right angle decreases (θ’is smaller than π/ 2)
23. γ = tan θ = δ/ y ≅θ in radians provided that θ is very small
γ = π/ 2 - θ’ = θ (in radians)
Normal strain causes only a change in volume. on the other hand,
shear strain causes only change in shape.
24. The plate is deformed into the dashed shape as shown in figure. If in this deformed
Shape horizontal lines in the plate remain horizontal and do not change their length
Determine (a) the normal strain along the side AB and (b) the shear strain in the plate
Relative to the x and y axis.
25. The rigid beam is supported by a pin at A and wires BD and CE. If the
load P on the beam causes the end C to be displaced 10 mm downward,
determine the normal strain developed in wires CE and BD.
26. The plate is deformed uniformly into the shape shown by the dashed
lines. If at A, γxy = 0.0075 rad., while, εAB = εAF= 0 determine the average
shear strain at point G with respect to the x’ and y’ axes.