# Stress analysis Definition and 28 Discussions

Stress–strain analysis (or stress analysis) is an engineering discipline that uses many methods to determine the stresses and strains in materials and structures subjected to forces. In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighboring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material.
In simple terms we can define stress as the force of resistance per unit per unit area, offered by a body against deformation. Stress is the ratio of force over area (S =R/A, where S is the stress, R is the internal resisting force and A is the cross-sectional area). Strain is the ratio of change in length to the original length, when a given body is subjected to some external force (Strain= change in length÷the original length).
Stress analysis is a primary task for civil, mechanical and aerospace engineers involved in the design of structures of all sizes, such as tunnels, bridges and dams, aircraft and rocket bodies, mechanical parts, and even plastic cutlery and staples. Stress analysis is also used in the maintenance of such structures, and to investigate the causes of structural failures.
Typically, the starting point for stress analysis are a geometrical description of the structure, the properties of the materials used for its parts, how the parts are joined, and the maximum or typical forces that are expected to be applied to the structure. The output data is typically a quantitative description of how the applied forces spread throughout the structure, resulting in stresses, strains and the deflections of the entire structure and each component of that structure. The analysis may consider forces that vary with time, such as engine vibrations or the load of moving vehicles. In that case, the stresses and deformations will also be functions of time and space.
In engineering, stress analysis is often a tool rather than a goal in itself; the ultimate goal being the design of structures and artifacts that can withstand a specified load, using the minimum amount of material or that satisfies some other optimality criterion.
Stress analysis may be performed through classical mathematical techniques, analytic mathematical modelling or computational simulation, experimental testing, or a combination of methods.
The term stress analysis is used throughout this article for the sake of brevity, but it should be understood that the strains, and deflections of structures are of equal importance and in fact, an analysis of a structure may begin with the calculation of deflections or strains and end with calculation of the stresses.

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1. ### Engineering Maximum normal stress and shear stress

First, I am trying to find the external reactions in A and B, but I have only one equation relating ##V_A## and ##V_B##, what other relation could I use ? Once I find the reactions, I can find the external moment as well. Then, I may draw the diagram of moments in each cross section and then...
2. ### How to calculate the normal stress of a Howe reinforcement?

This is the structure I already made the calculation of all the bars T = tension and C = compression, these are the results. now I am asked to calculate the normal stress in all the bars but I don't understand where to start, could you tell me how? here is the diagram of the first node but I...
3. ### Confidence in FEA stress values?

Hi all, I’m trying to get a better understanding of ANSYS as I don’t have a lot of experience with it. My question is with respect to a static structural analysis of a solid part: “how can I be reasonably confident that FEA is giving me reasonably accurate stress values?” I’ll analyse a...
4. ### Strength of a chain link

Hi, I am interested in the topic of hand calculations of chain link's strength. I am talking about a regular industrial chain with hanging weight. From what I've read, there are 3 potentially possible approaches: - Lame's problem (circular cross-section has to be replaced with equivalent...
5. ### Calculate the maximum vertical point force P that this beam can sustain

A simply-supported steel beam with a vertical point force P is shown in Fig. 2(a). A cross-section of the beam, which is composed of two identical C-shaped members bolted back-to-back, is shown in Fig. 2(b). Both C-shaped members have a uniform thickness of 1 cm. Pairs of bolts are located at a...
6. ### Beams-Bending stress exercise

A chimney has a rectangular cross-section with external dimensions 800 × 600 mm and wall thickness 150 mm. It is 5 m high. The density of the material is 2000 kg/m3. Assuming that the material is elastic, calculate the maximum uniform wind-pressure loading (N/m2) that...
7. ### Static Analysis of Bolts on Multiple Surfaces

I am trying to analyze if the bolts in my design are sufficient to support the load on a shaft. Unfortunately, the bolts are not all located on one face, and though I know how to analyze each face by itself, but I would like to be able to combine them all into one problem. I have attached a...
8. ### When does a cantilever beam fail in reality?

Hi, like the title says, how do we actually calculate when a cantilever beam fails in reality? We’ve been taught that these are absolutely fixed to the ground. However, in reality these would probably be bolted onto the ground, so how do we calculate the force trying to lift the fixed beam on...
9. ### Force from the legs of an electric motor due to torque

I need to perform stress analysis for the stand for an industrial sized electric motor like pic related. The motor stands on four legs. I need to know the force that the legs of the motor exert on the stand due to its torque. I have all the dimensions of the motor including weight and torque...
10. ### Airy Stress Func. Polynomial order to satisfy the biharmonic equation

Hello, When choosing a polynomial stress function Φ to satisfy the biharmonic equation, how does once decide on which order of the polynomial to choose? For example, is it based upon the number of boundary conditions, like a 3rd order polynomial would satisfy 3 boundary conditions?
11. ### Internal stresses of an accelerating body

Homework Statement Refer to image attached. Lets say I have a deformable solid that is being accelerated by a force that is equally distributed along the back face of the Main Body that is drawn in the picture. Attached to this Main Body is a Wing. At high accelerations, there will be inertial...
12. ### Tube Bending Stress

I have ran an FEA simulation on a lever to work out the stress on the part. I have now started doing some hand calculations to validate the software results and am struggling to get the values to match up. I am unsure whether my calculations are wrong, or whether the software is incorrect. The...
13. ### Multiple Beer Capper

So I've been working on a home project of creating a movable, self contained, ergonomic beer small (3-6 GA) home brew kit. I'd like to be able to fill and cap 6 bottles at one time. I'm working on a prototype for the filling process but need some ideas for how I could apply 6 caps to six bottles...
14. ### Circumferential tangent in the cylinder

Homework Statement A cylindrical vessel of height ##H## and radius ##R## contains liquid of density ##\rho##. Determine the circumferential tension at a height ##h##; also determine its maximum and minimum values. This is the scan of the original question(solved), I couldn't understand what...
15. ### Picking an element type for FEA

When choosing between a 2D 4-node quadrilateral element and 8-node for FEA stress analysis, why is the 8 node option preferred? I understand it has much more flexibility with different shapes due to the central mid node but are there any other reasons?
16. ### Stress in a rod with a hole for pin-joint

If a rod is in compression, will the minimum area on rod ( the section where there is a hole for pin) stress free? What if the rod is in tension? The rod BC is in compression and the boom AB is in tension? http://imgur.com/a/6asfB
17. ### Airy's stress function for a cantilever beam

I have to calculate Airy's stress function for a cantilever beam made of two different material along its length. The young's modulus of the first half is E1 and E2 for second half. The beam is made such that these materials are joined to each other one after other along its length. At the...
18. ### Automated Air Force Lug Analysis

Air Force Lug Analysis (section 9 here and summarized here) seems to be the best generalized method for comprehensive lug analysis. However, it relies on charts developed by the USAF in the late sixties. Every source I've found on the method uses those same images. I'm trying to make an...
19. ### Fatigue stress

Whether we are using Soderberg or Goodman line; it is two dimensional Cartesian coordinate system in which x-axis is the mean stress and y-axis is stress amplitude. For them to calculate we have two values one is maximum stress and other is minimum; I found on Quora.com that they are not...
20. ### Relationship between displacement and stress

Hi, Am I right in saying that if the gradient of displacement is negative then stress is negative as in a simple elastic case, sigma = E*du/dx? thanks.
21. ### Suitable metal for flooring in an industrial lift + power

Hi all, first post here. I'm currently faced with an assignment in a class where we really haven't been taught anything and have to figure it out on our own. We've been asked to design an industrial lift system to raise approximately 3000 kg up 25 stories. I have done a lot of research and...
22. ### Effective area for compression versus tension of a link?

I solved the equilibrium equations and found that link BD is in tension while link CE is in compression, but my resulting answers for normal stress were wrong. The solutions show that the cross area to be used for normal stress at links BD and CE should be different. Link BD should incorporate...
23. ### Metal prince rupert's drop?

i am wondering would that be possible to make a prince rupert's drop with metal.. would it end up having similar properties? (ie high compressive stress => stronger) or does molten metal flow too quickly?
24. ### Solid State Recommendations for Stress Analysis using Photoelasticity

I am looking for a robust text on stress analysis using photoelasticity. Razumovsky's "Interference-Optical Methods of Solid Mechanics" has been the best looking one so far, but with a >£100 price tag with only Chapter 1 (=30 pages) useful to me, I could do with finding an equally robust...
25. ### Stress anaylsis inquiry

Homework Statement For reasons based on cost,weight,availability , etc., the choice is made to construct the rod from aluminum of σall = 100 MPA. What is an appropriate choice for the rod diameter ? Givens: (P=50 KN) Homework Equations The Attempt at a Solution σall=P/A , then he get the...
26. ### Thermal Stress Analysis in a barrel of a T-80 tank

Homework Statement I need to find thermal stresses that will be produced in a tank barrel as a result of firing. First of all, I want to know if theses stresses can be small enough to be neglected? And if not, then how can they be calculated? I basically know the solution but I want to be sure...
27. ### Thermal Stresses in the barrel of a tank

I want to calculate the thermal stresses in the barrel of a tank. The barrel is smooth bore, auto-frettaged and chrome-platted. I want to know if the thermal stresses are small enough to be neglected and if not, then how can I find them? Relevant Equation: Thermal Stress= modulus * coefficient...
28. ### Stress analysis for a Bent Pipe

I am a student currently working on a group project regarding the design of a gooseneck for a sub-sea pipeline. For those not familiar, a gooseneck is essentially a 45 degree bent pipe, to be used as a connection between a manifold and a longer pipeline (a flexible riser). part of this design is...