Thermal FEA Calculations

Thermal calculations include stresses and strains induced by temperature differentials.

Introduction

NairnFEA can do thermoelastic calculations. In the presence of temperature differentials, the calculations will find thermal stresses and strains. This section is for FEA only; see separate help on thermal calculations when doing MPM calculations withOSParticulas and  NairnMPM.

Temperature Settings

Thermal stresses and strains are induced when the temperature in an element differs from the stress free temperature., which is set in the StressFreeTemp command. In scripted input files, the command is:

StressFreeTemp (temp)

In XML input files, the command, which must be in the [[MPM Input Files#MPM Header}<MPMHeader>]] block is

<StressFreeTemp>(temp)</StressFreeTemp>

where (temp) is the stress free temperature in degrees. The default value is 0. Note that some Material Models and Traction Laws depend on the stress free temperature on an absolute temperature scale and therefore calculations that use those models should always set this temperature in degree Kelvin.

The Temperature command sets temperature conditions to all nodes:

Temperature #1

where

• #1 is an <a href="function.html"> user-defined function</a> that gives the temperature on each node as a function of the coordinates of the node. The calculation will have residual stresses if it is a composite having materials with different thermal expansion coefficients or if the temperature field is non-uniform.