The tag has no usage guidance.

learn more… | top users | synonyms

1
vote
1answer
21 views

Young's modulus and geometry of test material

When measuring Young's modulus in a material, does the geometry of the material actually matter? I have seen several references recommend that I use cylindrical pieces. But, wouldn't the tests work ...
0
votes
1answer
23 views

Poisson's ratio and change in volume

The Poisson's ratio $\nu$ is always less than $0.5$. A traction force ($\Delta L >0$) can cause an increase in volume, while a compression force ($\Delta L <0$) can only decrease the volume. ...
-1
votes
0answers
25 views

Determine the shear in dislocation [on hold]

I don't know how to solve this kind of problem: Given a crystal and its volume V. This Crystal is subjected to a shear stress making a slip plane (h k l ) in a slip direction [h k l]. Given also the ...
1
vote
0answers
9 views

eccentrically loaded bolts in which the plane of loading is parallel to the bolt plane

This are eccentrically loaded bolts in which the plane of loading is parallel to the bolt plane.When deriving an equation to this particular problem almost all books start by assuming that ...
2
votes
4answers
940 views

Glass pipe cutting

I want to know how to quickly create the straightest possible breaks in glass pipes I apologise if this is only borderline suitable for a physics forum - I just hope experts with a lot of experience ...
1
vote
0answers
28 views

What is Lamè mode?

I am trying to read some of the articles that says Lamè mode. But I can't find in google that describes Lamè mode. Can anyone quote good reference for this term?
0
votes
1answer
25 views

An expression for stress power

I have seen it written that for a continuum undergoing deformation, if we ignore body forces and heat transfer, the work done is equal to stress power: $\cfrac{dW}{dt}=\sigma_{ij}D_{ij}$, where ...
0
votes
1answer
586 views

Volumetric and Deviatoric Strain Equation in 2D

Strain is defined as $$\epsilon=\frac{1}{2}\left( \nabla u + \nabla u^T\right).$$ I found a formula for the strain tensor in 3D decomposed into volumetric and deviatoric components: $$\epsilon= v + ...
0
votes
1answer
12 views

Trasversal wave on a rod velocity

What is the velocity of a trasversal wave on a metal rod? Does it depend on the shear modulus $G$ $$v_{t}=\sqrt{\frac{G}{\rho}}$$ Or on the tension $T$ of the rod? ...
0
votes
1answer
57 views

Momentum equation in a Lagrangian configuration

When writing the momentum equation in a lagrangian configuration is the the stress tensor used the first Piola-Kirchhoff stress tensor or the nominal stress tensor (which is the transpose of the 1st ...
0
votes
1answer
31 views

For a cantilever beam, is bending stress linearly proportional to elastic deflection?

Let's say I have a cantilever beam (a beam with a fixed support on one end only) and introduce a downward point force (by hanging a weight on it or something) at some constant distance from the ...
4
votes
1answer
47 views

Breaking strength of wet paper/cloth

In the Hollywood movie, Shanghai Knights (pardon me for the non scientific citation), Jackie Chan states that 'wet cloth' does not break easily. How true a fact is this ? We know from common ...
0
votes
2answers
522 views

does the thickness of a rubber sheet affect the tensile strength?

i'm really confused which thickness of rubber sheet i should choose. Does the thickness affect the tensile strength and elongation in any way? is there any relation between them? i would really ...
0
votes
0answers
12 views

High pressure vs low Mises

I have two high Young modulus materials, and a small layer between them which material have a low Young modulus. I apply constraints on one side and make a compression. Analysis gives me low von ...
0
votes
0answers
20 views

Absolute maximum shear stress due to combined loadings

In a prismatic beam subjected to 2D loadings, Is it possible that absolute maximum shear stress occurs at the point due to maximum bending stress (due to stress transformation)? Or that absolute ...
0
votes
2answers
2k views

How would one derive the equation to Thermal Stress?

The equation of thermal stress is: Stress =$\frac{F}{A}$ = -$E$ $a$ $dT$, where $E$ is Young's Modulus, $a$ is the coefficient of linear thermal expansion, and $dT$ is the change in temperature. I ...
1
vote
1answer
30 views

Confused about shear elasticity and complementary shear stress

I am a self learner of continuum mechanic. I am confused about simple shear stress in situation similar to figure 1, in case $F_\textrm{ext}$ is caused by external perturbation by i.e., human, what ...
0
votes
0answers
37 views

Phonon softening explanation

Is there a simple, intuitive answer of why phonons soften with strain? I am aware of the Grüneisen parameter but it just tells us there is a negative sign.
0
votes
1answer
168 views

Negative Sign in Compression Modulus

I noticed that the bulk modulus often has a negative sign appended to it in order to cancel with a negative change in an object's volume; this allows the bulk modulus to be positive. However, I ...
2
votes
2answers
288 views

Jaumann deviatoric stress rate

Background about terms in this question: Hookes law and objective stress rates From my understading, the Jaumann rate of deviatoric stress is written as: $$dS/dt = \overset{\bigtriangleup}{{S}} = ...
3
votes
2answers
90 views

in Science materials, what is difference b/w E and G?

I'm studying Science Materials on Callister's Materials Science and Engineering: An Introduction. I've never studied Mechanics (except for basic Physics courses), so I was wandering: when talking ...
0
votes
2answers
59 views

What causes tensile stress to decrease after a material/wire reaches its ultimate tensile stress?

I was reading the AQA A Level Physics revision guide by Jim Bretihaupt, and in the Materials chapter in the section to do with plastic deformation, it says: Beyond the ultimate tensile stress, the ...
3
votes
0answers
16 views

physical significance of the 'time of relaxation ' and 'time of observation'

Deborah number (used frequently in rheology) is defined as the ratio of the time of observation to the time of relaxation. In his article The Deborah Number, M. Reiner the man who coined the term has ...
0
votes
2answers
34 views

young's modulus factors

is young's modulus of a material different for various diameters of that material? I would assume it does, but I cannot find a reference. Is the young's modulus of 1mm thick steel the same with 10mm ...
1
vote
2answers
109 views

Extension in a vertically hanging rod [closed]

Consider a vertical rod hanging from a ceiling. Neglect lateral contraction and frictional forces and air resistance and change in value of $g$ with height. Case 1: In the absence of gravity, a rod ...
3
votes
2answers
75 views

What is the purpose of the Maxwell Stress Tensor?

In the calculation of the forces acting on a charge/current distribution, one arrives at the Maxwell stress tensor: $$\sigma_{ij}=\epsilon_0 E_iE_j + \frac{1}{\mu_0} B_iB_j ...
3
votes
3answers
390 views

Is it possible that Cauchy stress be asymmetric?

According to conservation of linear momentum and angular momentum, one can derive that Cauchy stress tensor is symmetric and hence has only 6 independent components. Is it possible that, when breaking ...
0
votes
1answer
68 views

How to model analytical expression for spring constant $k$ for certain structure?

In the deflection of beam, I learned that $$ \delta y=\frac{FL^3}{3EI} $$ where $$ I=\frac{h^3w}{12} $$ Together they comprise $$ F=\frac{Eh^3w}{4L^3}\delta y $$ How do I apply to four beams? ...
3
votes
1answer
33 views

determining the stress of a beam

I have a question regarding a beam. I first consider a force applied to both ends of a rectangular beam which is perpendicular to its cross section with dimensions w (width) and h (height). The length ...
0
votes
0answers
39 views

Axial loaded bars problem

I completely disagree with the following calculations: Based on my understanding, there is no force either internal or external applied to the Green bar, so it should be 0N. The reaction (internal) ...
0
votes
0answers
10 views

Flow Curve - Plotting Shear and Strain Rates at Different Pressures and Flow Rates in a Capillary

So I'm not really asking for a solution but more clarification on this type of problem since I'm kind of confused on the concept. So i have two capillaries of a different diameters and lengths. Im ...
1
vote
0answers
33 views

Why is the Elastic Modulus of concrete smaller than that of steel?

I am trying to get a basic feel for what the Modulus of Elasticity means for different materials. My understanding is that since E = stress / strain, a higher E ...
0
votes
0answers
31 views

Linear vs non-linear (finite) strain

I have a somewhat non-specific question regarding strain in materials. What I understand currently -Linear elasticity or infinitesimal strain theory is an approximation of finite strain theory that ...
1
vote
1answer
36 views

Which area to be considered in calculating stress?

During the calculation of longitudinal stress, we say that stress is equal to the magnitude of applied force divided by area of cross section. However, is this area of cross section, the ...
0
votes
1answer
65 views

3D beam deflection

How can you get formula for 3-dimensional beam deflection at the free end of horizontal cantilever due to the cantilever's own gravitational load? I assumed E= 160GPa, $\nu=0$, $\rho=2330kg/m^3$, ...
1
vote
0answers
26 views

Atomic Stress (Virial Stress) and Harmonic Springs

The general context here is polymer physics. The stress tensor in a bead-spring simulation can be easily computed using the Virial Stress (which may be named the Kirkwood formula, or the Doi-Edwards ...
1
vote
0answers
23 views

Pressure vessel analysis of transversely isotropic multilayer material

Suppose I have a transversely isotropic, hyperelastic material with known strain energy that is a fibrous composite. I am interested in an explicit formula for the displacements (so I can get the ...
0
votes
0answers
50 views

Question regarding the use of the Green-Naghdi Objective Stress Rate

The equation for the Green-Naghdi Stress Rate reads: $\boldsymbol{\sigma}^{GN} = \dot{\boldsymbol{\sigma}} + \boldsymbol{\sigma}\cdot\boldsymbol\Omega - \boldsymbol\Omega\cdot\boldsymbol{\sigma}$ ...
6
votes
2answers
649 views

Why do chocolate bars usually break at the cleavages?

Why do chocolate bars usually break at the cleavages? The chocolate bar is less thick at cleavages. How can we relate thickness and fracture point of chocolate bar?
0
votes
0answers
77 views

Why is maximum shear stress at 45 degrees instead of near 0?

I think I might havr an immensely stupid question but it's really bothering me so please be patient. I am not physicist smart. Look at this guy's question: ...
0
votes
0answers
8 views

Equation Governing Small Lateral Deflections z of a Uniform Membrane

The equation governing small lateral deflections z of a uniform membrane subjected to a lateral (dimensionless) pressure p is given by $$ \frac{\partial^2 z}{\partial x^2} + \frac{\partial^2 ...
0
votes
0answers
36 views

Do stress and strain contradict each other?

According to the book Engineering Physics by R.K Gaur and S.L Gupta Strain: Strain is a fractional deformation produced in the body when it is subjected to set of deforming forces. Stress: The ...
0
votes
0answers
31 views

From in-plane strain to Poisson ratio

I have recently been trying to simulate a graphene cantilever and thus I need to know the Poisson ratio, Young's modulus, and density. From literature it is easy to find the Young's modulus and ...
1
vote
1answer
52 views

Can a magnetic field weaken aluminum?

I'm wondering if there is any reason to suspect that applying a magnetic field to a piece of solid aluminum would weaken it structurally in any way. The application is that I would like to put a stir ...
1
vote
1answer
50 views

Elastic properties of materials at low temperature

It is common knowledge that materials are more brittle at low temperature. But does it apply also on elastic deformations or is it just matter of plastic deformations? Practically: Is it possible to ...
3
votes
1answer
68 views

Cauchy stress tensor in different coordinate system

The general form of the cauchy stress tensor is given by the dyadic decomposition $$\boldsymbol \sigma = \sigma_{ij}\,\,\mathbf{e}_i \otimes \mathbf{e}_j$$ I want to know how this can be expanded in ...
4
votes
0answers
68 views

Cauchy stress tensor for a spherically symmetric problem [closed]

Given a sperically symmetric problem, I am asked to show that its Cauchy stress tensor, in spherical coordinates will assume the form: ...
1
vote
0answers
29 views

Stuck with physics tensile strength problem

So this was a question in my exam. I am not asking for the solution rather some help at a step. A glass spherical shell of radius $R$ has a point source of monochromatic light of wavelength ...
1
vote
2answers
125 views

Elongation and tensile strength of rubber

I want to do some experiments on a neoprene rubber sheet (ex. supplier). When I went to order the sheet I was confused because the listed elongation and tensile strength for all sheet sizes (with ...
0
votes
3answers
76 views

Why are the x-components of the stress tensor ($\sigma_{xx}, \sigma_{yx}, \text{and } \sigma_{zx}$) different?

I understand the stress tensor at a specific point $P$ as follows. You draw a cube with its center at $P$ and look at its faces. The face with its normal vector in the positive $x$ direction has a ...