Questions tagged [stresses]

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6
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1answer
116 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....
4
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1answer
71 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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0answers
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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0answers
66 views

Designing a Safe and Crush-proof Pokemon playing card box using a 3D Super-Elipsoid

My friend has two young Pokemon-addicted sons who carry their 60-card playing decks with them everywhere, typically in a cargo pants pocket. Unfortunately, they have either managed to destroy every ...
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4answers
93 views

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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0answers
291 views

Why do we use the strain-controlled test for the compressive strength of concrete?

As you all now, a typical stress-strain curve for concrete under compression can be seen in any reinforced concrete design textbook. The decreasing part of the curve (post-peak) can be obtained by ...
3
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2answers
180 views

How to compute core stress in honeycomb structure?

Assume I have a honecomb(sandwich) panel under distributed normal load. Each edge of this panel is simply supported(pinned) as on the picture below: The problem is how to find the core stresses σ-z (...
3
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1answer
59 views

Normalizing the compressive stress to a cylinder

I'm not an engineer but a neuroscientist. I do research in spinal cord injury whereby a clip is used to clamp the spinal cord to induce a bilateral compression injury model. My research looks at the ...
3
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0answers
72 views

Normal stress - shear stress pairs not lying on Mohrs' Circles

The three Mohr's circles depict all the possible normal stress / shear stress combinations when material is taken and rotated along one of it's axes of principal stress. Nevertheless, it is clear that ...
3
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0answers
541 views

What is the longest self support length a chain one molecule wide can be?

Self-support length is the maximum length of a vertical column of the material (assuming a fixed cross-section) that could suspend its own weight when supported only at the top this is an important ...
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0answers
34 views

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 ...
2
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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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15 views

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 ...
2
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0answers
88 views

Is having a keyway in aluminium for 30Nm a bad idea?

I'm designing an aluminium shaft hub for a 16mm keyed shaft with a maximum torque of 30Nm. However, stress analysis tells me that the keyway can suffer too much stress: If my understanding is correct,...
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0answers
37 views

Unexpected stress concentration results

I've run some stress simulations but I keep getting some unexpected results. I have 3 parts connected using 4 bolts as follows: A torque of 1N is applied to the hole on the right to simulate a hung ...
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0answers
306 views

Double Shear Stress butt joint

A double shear butt joint is shown below in the diagram 4 plates are held together by two bolts. The applied force is 42KN. Determine the shear stress within the joint $$\begin{align} a &= 2 \...
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0answers
82 views

Shouldn't brittle materials be the ones failing under shear deformations?

It is known that brittle materials tend to fail under normal stresses, that is, tensile or compressive stresses. Brittle materials often are bound together into crystals by ionic bonds between atoms, ...
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0answers
436 views

Impact force with unknown deformations or time duration?

I expected to find more documentation on analytical solutions to determine the contact force between bodies, where deformations ($\delta = \delta_{1} + \delta_{2}$) and impact time ($t = t_{f} - t_{i}$...
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0answers
66 views

What is the load response of a threaded fastener?

Due to the fact that pipe flanges rely on bolts, and bolts rely on friction, it seems obvious to me that in deflecting to meet the load, the nut will immeasurably turn. So my question is - how much? ...
2
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1answer
328 views

Thermal expansion of a hole in a plate with a temperature gradient

I have a rectangular metal plate with a hole in it (with diameter of 300 mm). The plate has a temperature gradient going from one of its short sides to the other, I can measure the temperature ...
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0answers
21 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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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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78 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
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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20 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
154 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
85 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
86 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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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
738 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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0answers
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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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
68 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
112 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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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
91 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
416 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
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
206 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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2answers
36 views

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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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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0answers
26 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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0answers
22 views

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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0answers
19 views

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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64 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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0answers
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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0answers
29 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
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)...