Finite element method (FEM) is a method by which an approximate solution is obtained to the exact solution of some problem. For example, in linear elasticity, the solution domain, the material properties, the loading conditions and constraint conditions define a problem that has a unique exact solution in the displacements (u_EX). A finite element solution (u_FE) is an approximation to u_EX. The quality of approximation depends on the finite element mesh and the polynomial degree of the elements.

Read More on the Technical Briefs:

• Introduction to P-Version FEM Brief 
• Verification and Validation Paper
• Literature Study 

StressCheck is the only FEA software tool on the market that provides feedback to the user regarding the quality of the computed information.  This 'verification' process assesses the sensitivity of the computed data to changes in the mesh density, order of the element shape functions, and element mapping.  Verification is an important first step in validating the model.

• Verification - Am I solving the equations right?
• Validation - Am I solving the right equations?

It is clear that validation can only be achieved if verification of the data of interest has been completed.

General guidelines pertaining to the use of mathematical models in solid mechanics were issued by the American Society of Mechanical Engineers (ASME) in 2006 and adopted by the American National Standards Institute. This document describes the importance of verification and validation.

We invite those who are user's of FEA tools to solve the classical Girkmann Problem:

1. Stress resultants Qa (shearing force, kN/m) and Ma (bending moment, Nm/m)
2. The location and magnitude of the maximum bending moment in the shell.
3. Verify the results are accurate to within 5 percent.  Describe how accuracy was verified.
4. Software used, what mesh and type of elements were used.

ESRD recieved responses to this exercise from 15 FEA experts using a range of different modeling techniques and FEA software tools.