Questions tagged [stresses]

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Shear Stress Formula

Could anyone tell me what the variables in this formula are? $$\tau=\frac{S\;a\; \bar{v}}{I\; t}$$ I believe it is used for shear stress and that $I$ is moment of inertia but unsure on the other ...
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1answer
64 views

Deformation of a fixed-fixed beam with perfectly plastic yield stresses

Here's the setup: The problem asks to find the relationship between the force $P$ and the displacement of B ($u_B$). I have done this correctly: $$P = \left(\dfrac{E_1A_1}{L_1}+\dfrac{E_2A_2}{L_2}\...
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3answers
30 views

Failure load of hollow tube under transverse compression

How would one analytically calculate the maximum force a tube under transverse compression can withstand? I am specifically looking for a general equation to model the yield strength of a hollow tube ...
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0answers
32 views

Watermelon in a water bucket in a centrifuge [migrated]

We had a discussion about throwing a water melon using the SpinLaunch satellite launcher (https://en.m.wikipedia.org/wiki/SpinLaunch). One of the first points was that the centrifugal force would ...
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0answers
24 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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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
35 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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0answers
82 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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0answers
15 views

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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0answers
17 views

Should I use ST or LT values for extruded rod?

In MMPDS for AA7075-73511 (extruded rod) the Table 3.7.10.0(g3) show both ST and LT values for transverse directions. For a rod with circular cross section there is really no Short and Long transverse ...
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0answers
21 views

Limit state design/ LRFD of short steel columns

Why do we use the yield strength as the limiting strength in short column design when using limit state design. Why is the full capacity of the material not utilized (as is the case with beams when we ...
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0answers
181 views

Shear and normal stress in rivets

Hello everyone :) This is my first post here so please excuse any of my mistakes. I’m having some difficulty with solving the following problem. Let us have a thin-walled square pipe exposed to ...
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1answer
94 views

Analytical solution of thermal stress in a bi-metallic cylinder

As a side project I have looked to solve using Python an analytical solution for one-dimensional transient heat transfer in a thick cylinder with cladding on the inside surface, wherein the fluid in ...
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0answers
24 views

WEC linear inputs

I have seen some designs being made for linear generators for WEC(wave energy) applications. A buoy driving a shaft. But what if the shaft inside was a rack and pinion? If you converted the ...
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0answers
89 views

Understanding compatibility of strains

In mechanics, we have the so called compatibility conditions, which quarantee that when a body deforms, the strains are "compatible" in such a way to no discontinuities or gaps for inside the body as ...
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0answers
37 views

What is the difference between $K$ ,$K_{IC}$ and $K_t$?

I have seen three representation of stress concentration factor values $K$,$K_{IC}$ and $K_t$ now all that I know is $_I$ in suffix represents opening mode of crack.The suffix $t$ stands for tip....
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0answers
762 views

Derivation of Bimetallic Strip Stress in Roark's Formulas

I am trying to understand some analytic expressions given in the handbook Roark's Formulas for Stress and Strain for bimetallic strip stresses. Namely, Roark's Formulas give the formulas $$\text{...
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72 views

How to calculate the thickness of the residual stress layer generated by a machining process

Machining a metal part will create residual stresses on its surface due to the deformation that the process introduces to it, is there any model to estimate how thick will this stress layer may be?
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142 views

How to calculate the required thickness of a material to withstand a certain force or acceleration? [closed]

I am using a sheet of a certain material to dampen a product. Now, I have been looking at different soft dampening materials, and they're all defined by their durometer scale and other factors. ...
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1answer
56 views

Mohr's circle: maximum normal stress tensor

Given: $$ \sigma_{ij}= \left[ {\begin{array}{cc} -20 & 60 \\ 60 & 90 \\ \end{array} } \right],\quad i,j=x,y $$ I want to find the principle stress tensor $\sigma_{ij}^{pr}$. ...
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0answers
38 views

Internal stress tensor associated with centrifugal/centripetal load

I have some trouble to understand the relationship between internal stress tensor and the external traction force (in this example, the traction force is a volumic centripetal force). Consider a cube ...
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0answers
70 views

Calculating the Structural Forces Required to Support a Robot on an Overhanging Beam

this is my first time posting on here and I have a question regarding the structural properties a beam will need in order to fulfill some requirements we have for our robotics team. The scenario is as ...
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0answers
114 views

Equations for stress in a hollow prolate spheroid under external pressure

Are there analytical expressions (functions of geometry and applied pressure) for the stress in a hollow prolate spheroid, like there are expressions for the stress in a hollow sphere/cylinder?
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0answers
21 views

Consistent length in beam theories

From my understanding, the Euler Bernoulli Beam theory is mostly used for small angle displacements, and an implication of this assumption is that the length of the beam is subject to distortion and ...
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0answers
58 views

Shear stress derivative in polar/cylindrical coordinates

I have an embarrassing question that I just can't seem to figure out. I have a fracture problem that is infinitely easier to solve in cylindrical coordinates. The boundary conditions, however, are ...
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0answers
93 views

Calculating stress from elementary tension and bending formulas

I need help with this problem. Suppose we have a cantilever with width $-c \leq y \leq c$ and length $x=l$ fixed at $x=0$. We know that it is loaded by uniform shear along the lower edge with ...
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0answers
418 views

Will drilling a hole in a pane of glass reduce it's structural integrity?

I've got a glass box that measures 900mm x 450mm x 450mm. The width of the glass is 6mm thick. If I drill, cut, or grind a small hole in/through one of the faces; will it significantly affect the ...
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0answers
33 views

Pressure-volume relation of thin-walled shell [closed]

Attempt to edit into a more specific question as suggested by moderator: I would like define the shape and material properties of a 3D thin-walled shell/membrane-like structure (for instance a baloon)...
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1answer
281 views

Circular tube stress loading

I have a tube with a circular cross-section, this tube protrudes from the ground vertically for a section, then arcs over to one side. At the end of the tube, a flat plate is mounted to the end of it. ...
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0answers
2k views

How to calculate effective strain in plane stress?

What is the correct formula to calculate the effective strain under plane stress conditions? In plane stress it is assumed that the out of plane stresses are zero. The out of plane strains are not ...
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0answers
208 views

Distribution of shear stress in beam bending

Beer, Johnston, and DeWolf's Mechanics of Materials includes the following image of the distribution of shear stresses in a bending beam: (Axes and load vector carried forward from Fig 6.1 in the text ...
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3answers
46 views

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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5answers
118 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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4answers
83 views

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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1answer
446 views

What's the best way to design a joint with two fasteners?

When you're trying to design a relatively long joint with only two fasteners, what's the best way to arrange them? Since fasteners effectively radiate a circle of clamping force around them, what's ...
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3answers
419 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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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
58 views

Do we have infinite number of stresses at a point in a prismatic bar loaded in tenison?

Consider a prismatic bar loaded in tension as shown. I consider a point Q in the bar away from the ends. This point Q can be considered as an infinitesimally small element taken within the body. We ...
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4answers
79 views

Bar fixed at one end at heated

Consider a bar which is fixed at one of the ends. I increase the temperature of the bar by $\Delta T$. The sources I'm referring to say that stress developed in the bar will be zero because the bar is ...
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4answers
79 views

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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3answers
90 views

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
56 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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3answers
1k views

Engineering stress and true stress

I'm confused as to what is the difference between the above said stresses and their corresponding strains. If possible can anybody explain in detail what is engineering stress
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2answers
846 views

How to calculate external pressure resistance in spheres and cylinders?

Although I have seen a lot of literature online about how internal pressure resistance is calculated (i.e the pressure in a gas tank) I haven't found anything about the opposite scenario (i.e the ...
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3answers
76 views

Beam with width tending to zero

Suppose a cantilever beam (of rectangular cross-section) subjected to vertical transverse shear load at free end. If I consider any arbitrary cross-section then both bending and shear stress will be ...
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1answer
49 views

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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3answers
40 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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2answers
99 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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2answers
286 views

Thick walled cylinder theory - Stress/strain in ballooned out tube

I want to work out how much I can expand a piece of rubber tubing before it ruptures. The wall is 0.75mm and the ID 5mm. Hence I am working out the stress/strain from thick-walled cylinder theory ...
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1answer
579 views

Using strain energy to calculate deflection

I have a solids problem I cannot solve, I have the answer and I have attempted the question. I just need to know where I am going off track, (perhaps there was an issue setting up my deflection ...