How can i define Hook's Law interm of Tensor

In summary, the conversation discusses defining Hook's Law in terms of a tensor and its relationship to stress and strain. It also mentions the use of Lame coefficients and the generalized Hooke's Law in a general coordinate system. The application of this concept is also mentioned.
  • #1
Rousha
3
0
How can i define "Hook's Law interm of Tensor"

i want to define hoos's law interm of tensor:confused:
how cn i define it
can you all friends help me?o:)
i will be thanksfull to all of you
 
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  • #2
Hi Rousha, welcome to PF!

I'm checking I understood you right ... are you referring to the constitutive tensor of Hooke's law, the elasticity tensor [itex] E_{ijkl}[/itex]?
 
  • #3
need more help

i want to know that how can i define relationship between stress tainsor and strain tensor and also asked that is the transformation law of tensor obey in this relationship
thanx alot
 
  • #4
Write the generalized Hooke's law as

[tex]
\sigma^{rs}=E^{rsij}\epsilon_{ji}, r,s,i,j \in (1,2,3),
[/tex]

for relating the stress tensor [itex]\sigma[/itex] and the infinitesimal strain tensor [itex]\epsilon[/itex], where E is the elasticity tensor (by postulating the existence of a
strain energy density has 21 independent coefficients).
For homogeneous isotropic material the elasticity tensor, the generalized Hooke's aw can be expressed using the Lame coefficients as

[tex]
\sigma_{ij}=\lambda\delta_{ij}\epsilon_{kk}+2\mu\epsilon_{ji},
[/tex]

where the Lame coefficients are given as (by introducing the Young's
modulus E and Poisson's ratio [itex]\nu[/itex] )

[tex]
\lambda= \frac{\nu E}{(1-2\nu)(1+\nu)}
[/tex]

[tex]
\mu=E/2(1+\nu) .
[/tex]

The generalized Hooke's law in a general coordinate system can be written as (using the Lame constants again)

[tex]
\sigma^{pq}=\lambda I^{\epsilon}_{1} g^{pq}+2 \mu g^{ip} g^{jq} \epsilon_{ij},
[/tex]

where [itex]I^{\epsilon}_{1}[/itex] is the first invariant of [itex]trace(\epsilon)[/itex].
 
Last edited:
  • #5
thankx for ur reply:smile:
ok i understand this terms and finally i want to know that what is the application of this relation
 
  • #6

1. What is Hook's Law?

Hook's Law is a fundamental principle in physics that describes the relationship between the force applied to an object and its resulting deformation. It states that the force applied is directly proportional to the displacement or change in length of the object, as long as the object remains within its elastic limit.

2. How does Hook's Law relate to tensors?

In terms of tensors, Hook's Law can be defined as the linear relationship between stress (force per unit area) and strain (deformation) tensors. This means that the components of the stress and strain tensors are directly proportional to each other, with the proportionality constant being the elastic modulus of the material.

3. What is the mathematical expression for Hook's Law in terms of tensors?

The mathematical expression for Hook's Law in terms of tensors is σ = Eε, where σ is the stress tensor, E is the elastic modulus, and ε is the strain tensor. This equation can also be written in matrix form as σ = [E]·ε, where [E] is the elastic modulus tensor.

4. How is Hook's Law used in engineering and materials science?

Hook's Law is used extensively in engineering and materials science to calculate the stress and strain in various structures and materials. It is also used to determine the elastic properties of different materials, which is crucial in designing structures that can withstand certain forces and loads without breaking or deforming.

5. What are the limitations of Hook's Law in terms of tensors?

One of the main limitations of Hook's Law in terms of tensors is that it only applies to materials that exhibit linear elastic behavior, meaning that the stress-strain relationship remains constant throughout the loading process. Additionally, Hook's Law does not account for factors such as plastic deformation, temperature, and time-dependent behavior, which can affect the accuracy of its predictions in real-world situations.

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