The field equations of elasticity

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Discussion Overview

The discussion revolves around the classification of the field equations of elasticity, specifically in relation to other types of mathematical equations such as Laplace, Poisson, Wave, and Diffusion equations. Participants explore whether these equations fit into established categories of differential equations.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about the category of mathematical equations that the field equations of elasticity belong to, mentioning various classes of equations.
  • Another participant questions the necessity of having a specific name for these equations, suggesting that names can sometimes hinder understanding.
  • A participant asserts that the relevant categorization includes elliptic, parabolic, or hyperbolic types, stating that the displacement equation of an elastic medium is hyperbolic due to its structure involving time and space derivatives.
  • There is a query about whether the discussion pertains to Navier's equations, which is confirmed by other participants.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of naming and categorizing the equations, while there is agreement on the classification of the equations as hyperbolic. The discussion remains unresolved regarding the broader implications of categorization.

Contextual Notes

Some assumptions about the definitions and implications of categorization are not fully explored, and the discussion does not resolve the potential complexities of classifying the field equations of elasticity.

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TL;DR
What is the mathematical category of the field equations of elasticity?
First, my ignorance... I know there are classes of equations: Laplace, Poisson, Wave, Diffusion, etc.

(I suppose Laplace is a subset of Poisson, but that is not the issue).

Into what category of mathematical equations would you place the field equations of elasticity (stress/strain/displacement)?
 
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Why do you feel that they need to have a specific name?
 
Chestermiller said:
Why do you feel that they need to have a specific name?
Oh, I don't -- not in the least. Sometimes, names and categories undermine learning.

However, I DO know there are names given to the various types of differential equations and I am only interested to know if the field equations of elasticity are part of a particular category.
 
The relevant categorisation is as elliptic (Poisson), parabolic (diffusion) or hyperbolic (wave).

The equation for displacement of an elastic medium has at leading order two time derivatives on the left and two space derivatives on the right, both with positive coefficieints; we have therefore a hyperbolic system.
 
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Are you talking about Navier's equations?
 
Yes to Mason and hunt
 
Mason7 said:
I think you are talking about Navier's equation. Am i right?
Yes
 

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