The elasticity tag has no wiki summary.
8
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3answers
2k views
Why can one bend glass fiber?
Why can one bend glass fibers without breaking it, whereas glasses one comes across in real life is usually solid?
Is there also a good high-school level explanation of this?
5
votes
0answers
26 views
Measurement of Tangential Momentum Accomodation? [duplicate]
Possible Duplicate:
Measurement of Tangential Momentum Accomodation?
I am using atomic force microscopy (AFM) for characterizing
pores of the size of nanometers for application in gas ...
4
votes
1answer
100 views
Normal modes of a flexible rod clamped at only one point
I am interested in the vibrations of a thin, flexible rod that would only be clamped at one point, properly I'd like to calculate its eigenvalue. But the way I learned it in wave mechanics doesn't ...
4
votes
2answers
1k views
Why does the balloon pop?
When we pierce a balloon with a sharp needle, it pops and produce a great sound. But, It doesn't pop when we open the mouth of the balloon (through which we have blown air)...
So, Why doesn't the gas ...
4
votes
1answer
257 views
Origin of Elasticity
Why is that not all bodies are possessing Elastic behavior?
What is the origin of elasticity or plasticity? I mean, it's a
physical property.
But, How does it relate to atoms or molecules in solid ...
4
votes
1answer
526 views
Physical meaning of elastic constants of a monoclinic crystal
For the elasticity of a material, Hook's law can be written in tensorial form as:
$$\sigma = \mathsf{C}\, \varepsilon$$
where $\sigma$ is the Cauchy stress tensor, $\varepsilon$ is the infinitesimal ...
4
votes
2answers
741 views
Stress tensor in a cube with shear forces
I want to calculate stress matrix in a cube with two faces parallel to x axis and perpendicular to z axis (sorry I don't know how can I put a picture in this post).
There are two force uniform ...
4
votes
1answer
670 views
Rubber Band Forces
I have a question regarding the force a band places on an object. Say I have a rubber band wrapped around 2 pegs at a certain distance, and at that distance I know the pounds of force per inch it is ...
4
votes
1answer
398 views
A conceptual problem with Euler-Bernoulli beam theory and Euler buckling
Euler-Bernoulli beam theory states that in static conditions the deflection $w(x)$ of a beam relative to its axis $x$ satisfies
$$EI\frac{\partial^4}{\partial x^4}w(x)=q(x)\ \ \ \ (1)$$
where $E$ is ...
4
votes
0answers
38 views
Elastic band around a cylinder
An elastic band is stretched using a known force and then placed around a cylinder. How are the forces or tensions distributed? I assume there will be two components: firstly, a tangential or ...
4
votes
0answers
94 views
Why does the overhand knot jam but the figure-8 knot doesn't?
After tensioning a rope with an overhand knot in it, it is often very hard if not impossible to untie it; a figure-8 knot, on the other hand, still releases easily.
Why is that so? Most "knot and ...
3
votes
2answers
621 views
Good books on elasticity
Can someone suggest good books/textbooks/treatises/etc on elasticity? Thanks.
3
votes
1answer
162 views
What is the function of the top point of a bouncing ball?
A ball is thrown away as parallel to x axis from M(0,h) point with speed V . After each jumping on x axis , it can reach half of previous height as shown in the figure.(Assume that no any air ...
3
votes
1answer
378 views
Young modulus and Sound Velocity in a continuus medium
In elasticity theory, general equations of motion are:
$$\rho \partial^2_t \overline{u} = \mu \nabla^2 \overline{u} + (\mu+\lambda) \nabla(\nabla \cdot \overline{u})$$
where $\overline u$ are ...
3
votes
1answer
77 views
From the local Hooke's law to the global one
My system consist of a cylinder with axis Z that can contract and dilate along this axis. It obeys microscopically Hooke's law of elasticity:
...
3
votes
2answers
106 views
Does zero strain always imply zero stress?
In solid mechanics, can I always assume that if an object undergoes no strain, then no stress is applied to it? I think it's true only because I can't seem to find a counter-example.
3
votes
1answer
234 views
Is there any way to increase a rubber-bands lifetime?
Rubber-bands are simple, yet very useful. Old rubber bands(5 years?) get brittle? Why is that?
3
votes
1answer
130 views
How to write classical dynamics of solids in tensor form (relation of stiffness and viscosity tensor)?
This is a question about dynamics. If I have understood correctly there should be a tensor that describes the dynamics of a (solid?) body (= viscosity ?). I mean, tensor that includes the time ...
3
votes
2answers
547 views
Elasticity of Space; How does the expansion of Space effect gravity?
Does space have an elastic quality?
What I was thinking about was if space is expanding, is it being 'stretched', like a balloon being blown up, and if so, is this causing gravity to weaken? Imagine ...
2
votes
3answers
173 views
Simple elastic collision
If a particle with mass $m$ collides with a wall at right angles, and the collision is perfectly elastic. The particle hits the wall at $v\ ms^{-1}$. There is no friction or gravity.
So the particle ...
2
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3answers
275 views
Consistent theory of continuum
Why is there a consistent theory of continuum mechanics in which one just consider things like differential elements and apply Newtons laws? Is there a deeper reason for it. Is it the nature of ...
2
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1answer
160 views
What is the two dimensional equivalent of a spring?
I'm trying to model isotropic linear elastic deformation in two dimensions. In one dimension, I know that a linear elastic material can be thought of as a spring which obeys Hooke's law $F=-k\Delta ...
2
votes
2answers
139 views
Utility of displacements potentials in geophysics
In the elasticity theory, you can derive a wave equation from the fundamental equation of motion for an elastic linear homogeneous isotropic medium:
$\rho \partial^2_t \overline{u} = \mu \nabla^2 ...
2
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2answers
120 views
Fracture because of high-speed rotation
I was watching a rerun of an early MythBusters episode, where they look at whether CDs in high-speed drives can explode / fail simply because of being rotated too fast. The following are some ...
2
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1answer
71 views
Is shear elasticity the same as shear modulus?
I've encountered both the terms "shear elasticity" and "shear modulus". Are these the same?
2
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1answer
170 views
A differential equation of Buckling Rod
I tried to solve a differential equation, but unfortunately got stuck at some point.
The problem is to solve the diff. eq. of hard clamped on both ends rod.
And the force compresses the rod at both ...
2
votes
1answer
110 views
Why does elastic energy only depend on first derivatives?
Say we have an elastic material that is deformed with displacement function $u : \mathbb{R}^n \rightarrow \mathbb{R}^n$. It is reasonable to assume that the energy required for such a displacement is ...
2
votes
1answer
168 views
Is there symmetry in 2d stress tensor in linear elastic fracture mechanics?
Assumptions:
Cross terms in strain tensor are defined as equal $\varepsilon_{xy} = \varepsilon_{yx}$.
pure mode I crack.
Far from crack tip, material is purely elastic and we are way below
yield ...
2
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2answers
145 views
Cantilever Beam - Maximum Shear of the Beam
A cantilever beam $3\ \text{m}$ long is subjected to a moment of $10\ \text{kNm}$ at the free end. Find the maximum shear of the beam.
The answer is "There is no vertical load, shear is zero"
...
2
votes
1answer
94 views
Swords, impacts and elasticity for a noob
So I'm a game developer and I'm trying to understand some (extremely) basic facts of impact mechanics. I had read something entitled Dynamics of Hand-Held Impact Weapons, but it was a bit too ...
2
votes
1answer
112 views
(Botanical) branch bending under gravity
I'm a PhD student in maths, and attended my last physics class some 15 years ago, so you can imagine my competences in the field.
My supervisor (also not a mechanist) cant tell me how to proceed ...
2
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0answers
166 views
A question about surface tension of membranes and their curvature
I'm reading a review about membranes properties and I have reach a section about fluid membranes. The section discuss the principal curvatures ($c_1, c_2$) and the spontaneous curvatures ($c_0$). ...
2
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0answers
141 views
Displacement due to sinusoidal load on a finite strip in an infinite plane
From a paper on tunnel design I've been reading: (http://www.sciencedirect.com/science/article/pii/0886779887900113)
In the present application, the solu-
tion corresponding to a sinusoidal load
...
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4answers
61 views
Generic Born stability criteria
The tensorial form of Hooke's law for the strain-stress relationship in a crystal is (in the Voigt notation):
where $\sigma$ is the strain, $\epsilon$ is the stress and C is the stiffness tensor:
...
1
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1answer
100 views
Semi-conductor band-gap and deformation potential
Submitting a semi-conductor to stress leads to a deformation in the energy-bands, roughly described by:$$H_{ij} = {\cal{D}}_{ij}^{\alpha\beta}\;\epsilon_{\alpha\beta}$$
$\epsilon$ being the strain ...
1
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1answer
83 views
Modeling linear spring deformation in time
Suppose I had a spring (at equilibrium) and applied a certain force $F$, causing it to undergo elastic deformation. I know that by applying this specific force, hooke's law tells me that the spring ...
1
vote
1answer
251 views
Modulus of Elasticity
Consider a cube of unit dimensions. Let $\alpha$ and $\beta$ be the lateral and longitudinal strains. The expressions for moduli of elasticity on applying unit tension -
1) At one edge: Young's ...
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2answers
989 views
Why does a ball bounce?
If an object is acted on by equal and opposite forces then it will be in equilibrium, and it's acceleration or velocity (and so direction as well) will not be changed.
So when a ball bounces, it ...
1
vote
2answers
308 views
At what point does a projectile leave a slingshot?
Assuming a frictionless / "perfect" environment, and given a ball held in an elastic sling (like a hand-held catapult) where the pocket is lighter than the projectile itself, what is the point at ...
1
vote
1answer
270 views
Lagrangian density of linear elastic solid
I need the general expression for the lagrangian density of a linear elastic solid. I haven't been able to find this anywhere. Thanks.
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0answers
18 views
Explain the Föppl–von Kármán equations
I am a newbe to elasticity.
Could someone please explain to me briefly how the Föppl–von Kármán equations work?
What are we trying to solve for?
Is there some kind of intuition to the way they look?
...
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0answers
17 views
How do I find the force from drop shock using material properties?
I am dropping a cylindrical cast iron bar with a know elastic modulus and poisson's ratio, $E_{1}$ and $v_{1}$, onto a flat beam of elastic modulus, $E_{2}$ and $v_{2}$ so there is tangential drop ...
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0answers
76 views
Decomposition of elastic constants of a crystalline material
I have performed a calculation the tensor of elastic constants (or stiffness tensor) for a given crystalline material. From there, I calculated various elastic properties, such as Young’s modulus, ...
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0answers
144 views
Slackline Jump Tension
So a slackline is basically a bouncy tight rope.
I found a site that has a calculator for the tension of a static slackline
...
1
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0answers
88 views
Is there analysis library for stress-strain data?
I have three column data that has time-displacement-force from 1D tensile/compression test. Now I would like to get the standard mechanical properties of the material, like Young modulus, yield ...
1
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0answers
70 views
Physics for taffy pulling?
I am creating a simulation and am interested in pulling stretchy things and when they break, like taffy. I imagine this is a bit tougher then a simple equation like gravity, but I have no idea.
Is ...
0
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1answer
71 views
How must you spin the ball to make it alternate between 2 positions? [closed]
Assume any parameters you may need. Thanks in advance.
0
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1answer
58 views
Why elastic materials are discribed by tensors?
I am starting to read about elasticity of thin surfaces and I don't understand why tensors play such a major part?
What are the tensors describing about the material?
And just to clarify - Is there ...
0
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3answers
73 views
Hooke's law limitation question
Let's consider a spring. I am a strong man(well, lets assume) and I am pulling the spring. the work I do is being stored in the spring in the form of its elastic potential energy. Then suddenly, ...
0
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1answer
430 views
Calculation of a bending moment
I'd like to calculate the bending moment of a cantilever, fixed at its base, and submitted to a certain stress on a specific spot, but I can't find the proper definition of this bending moment (first ...
