Finite Difference solver for 2D Elasticity equations

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Discussion Overview

The discussion centers on solving the 2D Navier-Lame equations using a finite difference method on a rectangular grid. Participants are exploring the formulation of the problem and the challenges faced in obtaining expected displacement results when a deformation is applied to the boundary.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant describes their attempt to solve the 2D Navier-Lame equations using finite difference and the Gauss-Seidel method, noting unexpected results compared to solutions obtained from Mathematica/Abaqus.
  • Another participant requests more details about the problem formulation, emphasizing the importance of converting differential equations into algebraic equations for the iterative method to work effectively.
  • A third participant asks for specifics regarding the results, including the size of the rectangular grid, the values of the Lame parameters used, and the differencing scheme applied.
  • A later reply inquires whether the original poster has successfully solved the 2D Navier equation, indicating interest in the progress of the discussion.

Areas of Agreement / Disagreement

Participants have not reached a consensus, as there are multiple inquiries and suggestions regarding the formulation and solution approach, indicating ongoing exploration and uncertainty in the discussion.

Contextual Notes

Details regarding the specific formulation of the problem, the choice of parameters, and the numerical methods used remain unclear, which may affect the understanding of the challenges faced.

smmr89
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Hi

I've been trying to get a simple solution to the 2D Navier-Lame equations using finite difference on a rectangular grid. I want to see the displacements, u and v, when a simple deformation is imposed - e.g. top boundary is displaced by 10%.

The equations are as follows:

\begin{eqnarray*}
(λ+2μ)\frac{∂^2u}{∂x^2} + (λ+μ)\frac{∂^2v}{∂x∂y} + μ\frac{∂^2u}{∂y^2} = 0
\\
\\μ\frac{∂^2v}{∂x^2} + (λ+μ)\frac{∂^2u}{∂x∂y} + (λ+2μ)\frac{∂^2v}{∂y^2} = 0
\end{eqnarray*}

I have tried using the Gauss-Siedel method but am not getting the expected results (which have been sovled using e.g. Mathematica/Abaqus)

Is there something else I have to consider since the two equations are coupled via the mixed partials?
 
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It will help us if you tell us in detail how you are formulating the problem.

Gauss-Siedel is an iterative method that allows us to solve a system of linear algebraic equations. The details of how you convert you system of differential equations into a system of algebraic equations are important.
 
Also, what are the wacky results? How big is your rectangular grid? What values of the Lame parameters have you tried? Can you tell us what differencing scheme you used?
 
Hi Smmr98 ,
Have you sloved the 2D Navier equation?
 

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