Questions tagged [stresses]

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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
24 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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Can someone explain to me von Mises equation for multi-axial (2D or 3D) stress

I am trying to understand what is in the wiki about the multi-axial (2D or 3D) stress https://en.wikipedia.org/wiki/Von_Mises_yield_criterion An equivalent tensile stress or equivalent von-Mises ...
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3answers
51 views

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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25 views

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
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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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2answers
84 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
77 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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1answer
36 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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42 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
63 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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61 views

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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2answers
55 views

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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3answers
89 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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13 views

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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20 views

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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24 views

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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1answer
424 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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3answers
77 views

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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1answer
54 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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3answers
157 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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1answer
29 views

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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0answers
32 views

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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45 views

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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2answers
43 views

Why do I see stresses on the fixed support face of a solid body in FEA?

Below, I have shared pictures of a simple model in FEA. As it can be seen that the face onto which the fixed support is applied, there exists Von-Mises stresses. I cannot comprehend why. Since the ...
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Finding the Shear Center for a Beam with 1 Axis of Symmetry

I am trying to solve this problem of finding the shear center for the given beam and I have found that e = 35.94 mm, however the solution that was shared with me, had the answer of 39.17 mm. My method ...
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1answer
120 views

deformable object squeezing

I have the problem following. There is a deformable sphere with radius r. It goes inside a constriction channel with d*d cross section. Assuming that the sphere volume is constant and the sphere shape ...
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1answer
68 views

How to calculate the adhesion I need to keep a 3D printed bending part straight?

3D printed parts cool down during printing, resulting in thermal contraction which causes a bending moment and separation from the printing bed. The issue is solved by increasing adhesion to the ...
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1answer
39 views

Poisson relationship between area and length of electric wire

I was given the following formula to relate the change of area against the change of length of an electric wire with a Poisson ratio: $ {\Delta A \over A} = -2 \nu {\Delta L \over L} $ where $ \Delta ...
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75 views

Calculating the bending moment ($M$) of a beam as it relates to stress ($σ$) and strain ($ε$)?

I am trying to learn how to work out the bending moment for progressively complex systems to model a beam. I am assuming only one axis of motion (transverse = $y$). For the basic equations of motion, $...
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3answers
121 views

What exactly is Hooke's law defined for?

I used to think that Hooke's law was a relationship between how much a bar under uniaxial loading deformed and the internal force (per unit area) that developed within that bar. But this clearly isn't ...
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2answers
117 views

Shearing Stress at the Boundaries of two infinite Planes

This is a worked example on a book I am reading (Fundamentals of fluid Mechanics). He then asks "Can you explain the change in sign? [Hint: Sketch a sheared fluid particle adjacent to the top ...
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63 views

Is Viscosity = Slope?

studying fluid mechanics, I see that viscosity relates shear stress to shear rate, like a slope. However, on graphs I see that they draw a triangle, and where I would expect to see $\Delta \tau $, I ...
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1answer
47 views

Reinforce foldable table legs

I'm trying to build a table with 4 swivel legs that can be locked into arbitrary angles so that it can stand over one to three rows of storage crates in my garage: As you can see, the legs aren't ...
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1answer
169 views

How can I decrease strip tension with bridle rolls in tension leveller? How can I find total elongation after the strip exits initial bridle rolls?

I'm working on a tension leveller design which consists of 3 main sections. These are Input Bridle Rolls Zone: Increase the strip tension coming out of the decoiler. Leveller Zone: Strip goes through ...
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1answer
40 views

Where does the equation for shear stress of a rectangular beam (3/2 V/A) come from?

I am writing a report and need to reference every equation used. I am using the equation for shear stress in a rectangular beam of tau = 3/2 * V/A but am not sure where it came from or what textbook ...
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1answer
82 views

“Heavy-duty” or not, can my drawer slides really support this weight?

Okay, so recently I got a Dewalt 735 Thickness Planer. It's great at what it does. (It even LOOKS like it's ready to consume the tender flesh of lumber, like some twisted Victorian lumberjack... ...
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1answer
87 views

Stress Concentration Factor – Why a Specific Range?

I was trying to find the stress concentration factor for a specific situation and I found two different resources for it. Ref: Shigley's mechanical engineering design Ref: Roark's Formulas for ...
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2answers
49 views

Struggling to find solution: question 1 (Finding the maximum length possible of a rod with specific stresses in action)

Could someone please help with the problem below? Edit 1:My guess on this question is: when I plot in the formulas, the stress rooting from the bending moment overcomes greatly over the other ...
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1answer
110 views

Yield properties of plastic material

What is meant by yield of isotropic plastic material? How is yield of Isotropic plastic material different from the term normal yield which is referred as transition from elastic behaviour to plastic....
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Finite element welding simulation with commercial software? [closed]

I am looking forward some libraries/add-ons to perform welding simulation (thermomechanical coupling, steel alloys) using commercial software, like Ansys or Abaqus. My aim is to determine better ...
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3answers
124 views

Buckling of Parallel rods

I am trying to calculate critical force $P$, if two rods (same diameter and length - rigid fiberglass sandwiched on two steel plates) are parallel to each other. $$ P = \frac{\pi^2 EI}{(KL)^2} $$ I ...
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4answers
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The behavior of the stress-strain curve of metal, containing a void

Let's assume that in a metal sample without any dislocation, there is a void. Then we conduct a uniaxial tensile test.

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