Questions tagged [stresses]

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Ideal design for a long fruit plucking pole

I need to design a long (6-7m) pole for plucking fruits from tall trees. The following are the requirements: The pole material needs to be as light as possible. The pole should not be flexible ...
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Spinning disc stress distribution

For a thin spinning disc, is the boundary condition on the outer surface that the radial stress is zero? If so, how is this consistent with the fact that the outer surface of the disc has a ...
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The hanging of lead weights in the Cavendish experiment of 1798

I'm working to build the Cavendish experiment of 1798 according to Cavendish's own specifications. I have a question about the hanging of the 150 kg lead weights. As seen in the image, there is a ...
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Should I calculate hook part of hook with metric thread? If so, then how do I do it?

I am making a project for one of the courses I have on my university. I have coaxially loaded hook: Now, I know it will be streched in a segment that is marked with digit 2, Initially I have ...
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What are the physics behind a TV wall mount?

As I was installing this wall mount, I began to wonder how exactly physics is at work with it. In other words, how does the design of the mount play a role in ensuring that the mount itself supports ...
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How to minimize perpendicular strain on cam-follower system?

I have a cam+follower system as shown in the picture: As the arched cam moves in the horizontal direction, the (fixed) follower gets pushed in the vertical direction. But as the cam approaches the ...
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2 answers
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Shear Strain and no change in volume of the element

Consider that at a particular point of the body the state of stress was that of a pure shear one, with $\tau_{xy}$ and $\gamma_{xy}$ as the shear stress and strain. I read two statements in two ...
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What would happen if we applied a stress greater than the yield stress to a rigid-perfectly plastic material?

Say we had a material that was rigid perfectly plastic, with a stress-strain characteristic as shown: Say that we are drawing this material through two dies, something like this: What would happen ...
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How to solve this complicated truss system?

Below is a truss I simulated in a truss calculator. I'm just wondering, how to solve for the compression and tension of each member and are there any method that can solve this? My solution is I ...
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4 answers
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What is the significance of brittle materials and why do we use them?

What is the significance of brittle materials and why do we use them? As you can see in the stress-strain curve, brittle materials have extremely low plasticity, in which cracks can initiate without ...
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How to use Mohr's circle to find stresses on a slanted plane?

Here is my attempt to the problem: Does this make sense? rotation clockwise 60* from horizontal to normal of the slanted plane , therefore $2 \times 60$ clockwise as well on Mohr's circle. I am ...
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Principal Planes and Principal Stresses

Consider that a state of plane stress exists at a point and the stresses acting on an element taken at that point are given as, The normal stress acting at any plane of this element inclined at an ...
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What does negative shear stress mean $\tau \:=\:\frac{VQ}{It\:}$?

$\tau \:=\:\frac{VQ}{It\:}$ My confusion lies within $Q$ term. $Q = yA$ where $A$ is the cross-sectional area of the segment that is connected to the beam at the juncture where the shear flow is ...
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Stress on a statically indeterminate beam with nonuniform temperature distribution

The bar below has length $a$, an uniform cross-section and has both ends fixed to walls. The temperature at the left end is raised by $\Delta T_1$ and that of the right by $\Delta T_2$, where $\Delta ...
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First moment of area about the neutral axis

Consider a homogeneous beam with a rectangular c/s, its neutral axis will be at equal distances from the top and bottom edges. The first moment of the entire area about the NA will be zero, since we ...
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Inverse Power Law for Accelerated Failure Times

I am working with some subsea cable data. I have $n$ samples that are split into three groups (sized $n_1$, $n_2$ and $n_3$). Each group goes through a different acceleration process until failure. ...
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Equality of Normal Stresses on opposite faces of the element

Consider a body, which is arbitrarily loaded by some loads. I take an element at some point of the body as shown, and show the stresses acting on its faces. To specify a face I will be using the axis ...
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Due to what reason are the beams getting elongated?

I was studying about shear stresses in beams, where one of the ways the textbook tried explaining intuitively the presence of shear stresses in beams was: Source : Mechanics of Materials, R.C. ...
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Choosing metal plate to spread point load

I have a heavy object standing on 4 legs (about 30 mm in diameter each) on a wooden floor. The object is soon going to become even more heavier and I am concerned the legs could penetrate the floor. ...
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Can modern residual stress measurement replace finite element calculation?

Residual stresses are created by the manufacturing process and exist in materials and structures. Now, people develop many methods to measure residual stresses. Those methods can be divided into ...
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How to calculate press load for an interference fit with no friction coefficient between the materials (shaft & hub)

Press-fit load calculation always takes friction into consideration and gives you the load expression as follows, $$F = µ\cdot PA$$ where µ is the friction coefficient, P (Interference Pressure) is ...
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Stress-strain Curve Interpretation

A significant barrier to my understanding of typical engineering stress vs. engineering strain curves is that for certain values of stress, there are multiple values of strain (i.e., the stress-strain ...
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Slope of the Bending moment diagram where a point force acts

Consider a beam that is arbitrarily loaded and at any distance x, we take an element in the beam between two sections, where a point force acts as shown. Let us assume the directions of shear force ...
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Relationship between shear force and load intensity

The book I'm referring to for studying beams, said that its quite cumbersome to construct shear force and bending moment diagrams, by writing the SF and BM equations for each segment of the beam and ...
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1 answer
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Why does Poisson's ratio always have the axial strain as the denominator?

Why can't we divide the lateral by the axial strain? Why does the axial strain always have to be the denominator? Would it matter if I was careless and accidently switched them around?
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Shear force in a beam at ends

Consider a cantilever beam acted upon by a point load at its free end. The shear force diagram is shown. I have a little doubt,is the shear force at x= 0 ,both 0 and $-W$ or just $-W$? Similarly at ...
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5 answers
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How do ball bearings not crack from a load concentrated on an infinitesimally small point?

How do ball bearings last? Most bearings in a standard hub (bottom of the image) are not actually taking a load. Only the single ball that happens to be at a particular location while spinning takes ...
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How they derive The Green strain tensor?

in this paper they give the deformation tensor and the green lagrange tensor without explanation i have some difficulties with tensor calculus ,Especially dyadic product can some one explain it in ...
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What is meant by Direct and indirect stress?

The book that I'm referring to for studying Strength of Materials states that: "The loading case discussed here is an example of simple or direct shear, since the shear is caused by the direct ...
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2 votes
1 answer
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A close coiled helical spring with torque acting about longitudinal axis

Consider a close coiled helical spring which is acted upon by a torque about its longitudinal axis as shown. I'm interested in knowing the effect of this torque on the spring wire. Here's my take: I ...
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2 answers
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Deformation of a plane in Torsion of a Circular Shaft

Consider a shaft which is fixed at one of the ends and is acted upon by a torque at the free end as shown. We take a plane inside the shaft as shown in the figure before the torque is applied. I'm ...
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1 vote
2 answers
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A question on thermal stresses

I'm studying strength of materials at undergrad level and was taking a test in the same. One of the questions from the test goes like this In my understanding since the coefficient of thermal ...
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3 answers
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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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1 answer
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Maximum shear in a beam

Engineering books and lectures typically make two things clear: Maximum bending stresses (normal) develop at the beam surfaces, that is, at the greatest distance from the neutral axis. Shear stresses ...
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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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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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where did the concrete splitting test calculated stress formulat come from?

In compression test of cylindrical concrete sample we get the normal stress easily by dividing failure force by sample cross section, but how we can explain the formulat used to determine tensile ...
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1 answer
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Does F_x generates "Transverse Shear Stress" shear stress at the fixed end A?

Considering the applied forces $F_y=F_y=0$ and $F_x=400$ lbf, what type of stresses does $F_x$ produce? I understand that $F_x$ causes tensile and bending stress but not sure about the transverse ...
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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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2 answers
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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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Calculating member stress in a truss

I have the following question: Here is my attempt: Is this correct ?
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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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1 answer
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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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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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2 votes
2 answers
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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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2 votes
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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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2 answers
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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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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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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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