Questions tagged [stresses]

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Find hotspots in a system

In the image, I have a depicted a system which is undergoing fatigue. Using appropriate solver I have determined the life of each nodes and it is stored in a .csv file. Also I have the connectivity of ...
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26 views

Calculating member stress in a truss

I have the following question: Here is my attempt: Is this correct ?
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2answers
58 views

FEM boundary problem in structural mechanics

I have spent way too much time in the last weeks/months implementing and writing my own finite element solver from scratch. I successfully implemented 2D and 3D elements and wanted to verify a few of ...
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1answer
26 views

Why von-mises criteria considers the second invariant of deviatoric stress? [closed]

Why only the second invariant is considered? What about the third invariant?
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Bearing stress in Bolts

Consider the arrangement shown below. It consists of a bolt, clevis and plate. Since, the clevis and the plate press against the bolt, the bolt will be acted upon by forces 1,2,3 (as shown). There is ...
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4answers
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When we replace supports distributed reaction by point reaction in thin beams, is that considered an application of Saint-Venant principle?

I read about Saint-Venant principle which is about the effect of replacing forces by equivalent forces system that effect on the same small region of a rigid body, all examples I come across are on ...
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418 views

Does welding two metal parts together increases or decreases the strength locally there?

I have a structure made out of steel consisting of many thin rods and some of them are welded to each other. I conducted a simple FEA static structural analysis to determine if the structure would ...
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How do you estimate the energy of an impact?

I am trying to determine the energy of elastic stress waves generated in a solid by an impact. I have a time domain waveform from a piezoelectric transducer that was placed next to the impact site, as ...
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2answers
70 views

I can't decipher the string printed on my steel pipe (to find the yield stress)

TLDR; Can you please help me understanding the string in the picture and help me finding the yield stress that my metal can handle? Full story I am trying to estimate how much load some zinc-coated ...
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2answers
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What happens to the maximum force in bar under bending when its cross sectional area is decreased?

Consider a rectangular cross sectional beam for instance with dimensions a = 1 mm and b = 1 mm, fixed at one end and transverse force at the other. I will get the maximum stress at the farthest away ...
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39 views

Find the maximum stress at a point in a machine member

A machine member having a diameter of 50 mm and a length of 250 mm is supported at one end as a cantilever subjected to different forces as shown in the figure. Find the maximum stress at points A and ...
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4answers
95 views

Mechanics: example of less mass/volume gives more strength

Lets assume we have a mechanical element from uniform material that is supposed to work in a static load conditions. Moreover lets assume there is no gravity or gravity is negligible. Are there any ...
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1answer
41 views

How do I calculate the strength of a carbon fiber tube?

I am not a mech engineer and have been struggling with this for a while, I feel like it is pretty straight forward but I'm missing something. The problem is a horizontal tube that is supported at one ...
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trying to find maximum torsional stress

I was wondering how I could get Ttmax (maximum torsional stress) or rather what the formula for it could be
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Stresses due to combined loadings in a bent shaft supported at both ends

I was hoping someone might be able to help clarify where I might be going wrong with this question. I am being asked to essentially determine the maximum normal and shear stresses at the rigid support ...
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Why is my FEM analysis producing unusually-large stress results?

This is my first time performing an FEM analysis, and I'm using the Ansys Workbench and Mechanical software. My situation is pretty straightforward--it's a straight beam that is fixed at one end and ...
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2answers
138 views

Is there any difference between an-elastic and visco-elastic materials?

Most of the sources that I had read about either talks about anelasticity or viscoelasticity, they don't compare both. From what I have read so far ,both anelastic and viscoelastic materials are the ...
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3answers
214 views

Does perfectly elastic and perfectly plastic material make any sense?

I have been reading about the elasticity of materials and most often in engineering there is always some ideal concepts which are the extreme cases. So is there any particular definition to what is a ...
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4answers
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Do windows add to strength or rigidity?

A friend who repairs washing machines told me that the window adds rigidity to the front cover and compresses the gasket. Also the windows of cars act against shear forces, he said. Do you know ...
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112 views

Why ships have extremely thin plates?

The thickest plate of the famous Ever Given as an example with its 400 meters length is 30mm thick. And a good part of its skin is even thinner. If we compare with a car 2 meters long it is amazingly ...
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Elongation due to tensile forces on a cylindrical object

I have been presented with the following problem. I think that I'm okay with calculating the stress and strain, but am unsure on how to tackle the elongation. I think we would need to assume that the ...
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1answer
25 views

a model of a solid using trusses to approximate internal stresses?

my question is as follows: could the stresses on a solid body be aproximated with a discrete model based on trusses?, this is, that the result yielded by the analysis of the truss structure will ...
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3answers
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How can I visualize shear stress concentration?

I have seen plenty of diagrams showing parallel axial stress lines to aid in understanding the stress concentration around corners and other things. But this doesn't seem to be a good visualization ...
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Computing forces and moments acting on the sides of a rectangular shell element from corner forces and moments

I have a FEM program for shell elements implemented through the direct stiffness method. Using this program corner displacements of shell elements due to external loading are obtained through the ...
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2answers
139 views

How exactly do forces transfer in different directions?

If we imagine the load being placed at the top of the below triangle, I realise that the downwards force is transferred into one which goes in a 'south east' and 'south west' direction down to the end ...
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1answer
47 views

Why do we not want our stress state to be like this?

In this article they mention that Cauchy stress is defined by studying the forces acting on the deformed body, and these forces are constant in space. But if a body is subjected to pure rotation, the ...
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94 views

Can a beam be too short to experience bending stress?

The question in the title says it all. I've got a a configuration where I'm using a bolt to support a load. The way its set up, the bolt will have a very short cantilever on it. When I calculate the ...
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3answers
90 views

Can we say that stress strain curve for a tensile test is function of strain rate and temperature?

I am currently studying about tensile test where it is saying that it is conducted at a constant strain rate. Also, it is said that it is conducted at a particular temperature. So can we say that ...
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Why exactly does a washer help distribute the stress around a bolt?

Usually the reason for having a washer under a bolt head is stated to be that it helps to evenly distribute the stress to the clamped material surface. But why is this? I would understand if the ...
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39 views

Applying forces from the inside of a bar

I was reading Schaum's Outline: Strength of Materials (fifth edition) when I came across this solved example problem from the Tension and Compression chapter: The solution was clear to me, however ...
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Adding tension to a model of a Timoshenko beam?

I am interested in modeling a Timoshenko beam: https://en.wikipedia.org/wiki/Timoshenko%E2%80%93Ehrenfest_beam_theory However, I would also like to add tension to the beam so that it can vibrate like ...
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2answers
49 views

Computing the stress field of a structure made of 4-nodes shell elements (accounting for membrane action, bending and shear)

I am trying to implement my own FE code for shell structures. Most literature provide formulations and strategies on how to compute shell element stiffness matrix. I can already compute deformations ...
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2answers
83 views

How do I start determining the forces in the 3 bars?

For part A I have $\Delta$A + $\Delta$B = $\delta$. For part B I've tried summing forces at the joints but keep getting lost. Any help is appreciated my final is on Friday.
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Why is it more convenient to express stress tensor in Material rather than Spatial coordinates?

I was reading chapter introduction about Stress and the author wrote the following about stress tensors: "Since the current configuration of many problems, especially those involving solids, is ...
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An analytical expression to calculate the stress triaxiality for a single notch sample

As far as I know, there is a formula (Bridgman) for the calculation of stress triaxiality for a sample having a notch on either side or for a flat grooved sample. Now my question is, if I have a ...
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Why is the yield strength of steel assumed to be less for a thicker element?

The above image is part of table 3.1 of Eurocode steel design standard. Looking for example at the first row (steel grade S 235), we see that there are two values for yield strength $f_y$, one for ...
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119 views

Calculating Load On Winch From a Distributed Load?

I am in the process of building an antenna mast that can tilt from horizontal (down) to vertical (up). The mast (arm) is 360" and weighs a total of 105 lbs. I need to calculate the amount of ...
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How to calculate minimum and maximum cross-section of a compression clip

I am trying to design and 3D a custom snap in fastener, and I am having a hard time figuring out what cross section it needs to have so that it does not break when compressed, but also isn't so that ...
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Why doesn't the Stress Power in the theorem of the expended mechanical power contribute to the kinetic energy?

The following is the formula of the expended mechanical power: $P(t)$ $=$ $\frac{d}{dt}$ $\int \frac{1}{2} \rho\ v^2 dV$ $+$ $\int \sigma \colon d\ dV$ where $P(t)$ is the mechanical power entering ...
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How to solve stress/strain constitutive equation for system of springs and dampers with a Coulomb friction element added in?

I am attempting to solve the stress/strain constitutive equation for a system of springs, dampers, and a Coulomb friction element. Basic examples for such constitutive equations can be found in this ...
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871 views

Why is the Stress vs strain diagram preferable to the Load vs displacement diagram?

I’m really unsure what is the difference between stress vs. strain and load vs displacement graphs and why stress-strain is better. I know that the units are different: stress is in MPa and the load ...
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Shelf Reinforcements

Hi I know this is a little bit of a strange one, but I’ve got a relatively cheap shelving rack that I bought to make good use of garage space. I have included a pic, It’s footprint is 1220mm x 610mm ...
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60 views

Is it possible to use Plain Cement Concrete post for fencing?

I am in need of around 700-800 posts to fence my farm in a semi-arid area in TN state, India. In my place granite posts mined from quarries are normally used. It costs around Rs 300-400 per post(6-7ft)...
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299 views

Why is it said that the flange of an I beam carries most of the moment?

It is often said for I beams that the flange carries most of the moment subjected to the beam, while the web carries most of the shear force. The latter is obvious from pictures like above, showing ...
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If an airfoil underwent horizontal loading, would it stiffen the airfoil? [closed]

I am designing a wing for a Vertical Takeoff and Landing aircraft. I am trying to choose a wingtip winglet for my aircraft. One of the option is a aft-swept wingtip winglet. However, this structure ...
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What are the limits of small 3D printed gears?

How much tangential force should I expect a 10~20mm pitch diameter/1.5mm gear module 3D printed rack and pinion system to support without breaking nor sliding?
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Is there a mode of failure criterion for a valid unconfined uniaxial compressive strength test for intact rock core specimens?

I have read the latest revision of the ASTM D7012 standard, which includes the test procedure for determining the unconfined uniaxial compressive strength of intact rock core specimens. There, I do ...
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Stress Tensor components

Given an equivalent stress vector(or Traction vector) in a plane stress state, how can one determine the 3 components of the 2*2 Tensor matrix, i.e. sigma_x, sigma_y and tau_xy?
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Stress Transformations

In plane stress state: How can one comment about the state of stress for the given condition? I am not sure but I guess that we can use the principle of superposition. Though I do not know how can I ...
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How do I calculate the strength to weight ratio of this object?

I have an object that weighs approximately 10 grams = 0.022 pounds. I know it can hold at least 45.1 pounds without breaking. It's a cube-like object so I placed many books on top of it and weighed ...

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