What is Stress analysis: Definition and 69 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.
I was required to calculate the torsional stresses on these welds (in green) with the point of rotation G. However this doesn't fit any case in Shigley's so I'm at a loss as to how I should have calculated this. As advised by the teacher, I ended up replacing the keys being welded with full...
I'm designing a custom lifting plate that has two shackles hanging from it and a large slot at the top for hooking into an overhead crane. I have a few stress analysis questions:
1. The plate will be cut on a waterjet table, which means the slot will have sharp edges, and that the hook will...
Hi
im trying to understand truss bridges.
Where would max stress be in single span truss bridge if it was evenly loaded across the bridge?
I thought single span truss bridge, max stress would be in the ends of the bridge. it would act like a simple supported beam with max bending motion being...
Hey
Im doing FEA and got stuck on question. The diagram go me stuck, because looking through the workbook it says high stresses are in red and low in blue, whereas they included both different kind of stresses on the same diagram and no data.
Note: High Compressive strains are noted by blue...
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...
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...
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...
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...
Hi,
I wonder how to approach stress analysis of quick return mechanism used in shaper machines (see the diagram below):
The first issue is: which moment in the working process of this mechanism should be used for analysis (when will the mechanism experience largest loads)? So far I assumed...
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...
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...
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...
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...
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...
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?
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...
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...
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...
Moderator Note: Thread moved from forum Atomic, Solid State, Comp. Physic, so no homework template shown.
What function do they use Taylor's formula on? And can you show how they derive it? I know how one derives Taylor formula. Thanks! The text i taken from this...
Problem attached.
I would appreciate anyone's help. I am an alloy chemist working on an MS degree in materials engineering and have come to the mechanical engineering part of the program and am feeling a bit behind. Deriving an equation for this case is proving to be difficult for me although...
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...
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?
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
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...
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...
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...
Hi,
My name is Gordon Mutten. I have been a stress engineer for 40 years working on aircraft, spacecraft , and several other products involving metals and composites etc. I would like to offer my help with simple stress analysis questions. I am soon to start a website for this subject so I...
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.
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...
I have to model a storage vessel in ansys and perform stress analysis for it. I have no idea about which element types I will need for the analysis. I have calculated the design dimensions for the vessel. I am a beginner at ansys and know only how to deal with simple structural and thermal...
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...
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?
Hello, I'm trying to follow along with the stress analysis derivation for flywheels given here, but I'm stuck at the point where it says:2⋅σ t⋅δrsin(1/2⋅δθ) + σrδθ - (σr + δσr) (r + σr )θδθ = ρr2ω2δr ⋅δθ
in the limit reduces to:
σ_t- σ_r - r⋅\frac{dσ_r}{dr}= \rho⋅r^2 ω^2
I'm a little rusty...
Hi dear friends. I have a big problem and I need your help, I've realized that the joint connection I've drawn (and it is made already) was (most probably) wrong. There is a plate that is bolted to two U beams and the plate is welded to a horizontal I beam at the top. Please take a look at the...
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...
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 EquationsThe Attempt at a Solution
σall=P/A , then he get the Area...
Determine the tensile stress in the bolted connection shown below for the load F = 210 kN. Using a safety factor of 2, determine whether the plates will fail or not if the yield strength of the plate material is 270 MPa and the thickness of the plate is 12 mm. The nominal diameter of the bolts...
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...
Homework Statement
If I have two spars running through an airfoil, which can be assumed to be two dimensional, which method would I use to find the stresses at the points where the spars are fixed? The loads would be lift and drag and what I need are the bending and shear stresses. Because I...
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...
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...
I'm faced with a problem where I need to cut the length of the rod body on a tie rod, however, I need to prove that this modification will not affect the entire structure seeing as how the critical points of stress on a tie rod exist at the clevis and end rod. How would I go about proving that...
I could use some guidance as to how I would analyse the stresses in a ring girder similar to the one shown in the attached picture. I have found the stress in the columns that support the ring but I do not know how to find the maximum stress in the ring. The best I have been able to come up with...
I'm doing a survey on the topic of "gas turbine blades stress analysis" to see what areas are not focused on in this subject.
I've found that not many people talk about the aerodynamic forces on the blade. Am I missing something, are they included in the calculation or are they too small to...
I am a CSE researcher with a not so in depth background of physics. As a part of my research in object modelling, I am trying to computationally figure out the stress for various objects by using Finite Difference Method (not FEM which is the defacto standard for stress analysis). The reason for...
Hi Everyone,
I am a student studying civil engineering and want to do a stress analysis on a part I have made in Solidworks (CAD software). However, it is somewhat complex for handcalculation purposes, so I have simplified it down. I want to run a full ansys simulation on the part, however I...
Hello All,
I have a fixture that is used for lifting an engine. See attached image for the part in question. You can see in the 'front' view the hole where a pin passes through the part and the lifting lug of the engine. You can also see the loading.
We want to machine the part down such...
Hi,
I'm trying to calculate the maximum bending stress in a beam with a varying cross section. I found a great resource (link below) that gives examples on how to do this but am a little confused. Basically the equation used is σ=M/Sx I know what σ and M are, but I haven't a clue what Sx is...
Dear all,
Welcome to this post.
I have a question. I have a main piping loop around a cylindrical vessel for which stress analsysis is don't and supported properly. Additonal six loops are to be installed in that main loop. This additional weight is coming on the main piping loop. The...