Numerical Simulation
Predictive calculation of mechanical deformation caused by temperature changes is essential for preventing structural failures in multi-material assemblies. In this engineering domain, thermal stress finite element analysis discretizes the physical structure into small subdomains to solve the coupled temperature and displacement equations. This method calculates where stress concentrations will develop when the structure is heated or cooled.
Governing Equation
The underlying calculation is performed in two sequential steps where the temperature distribution is solved first before the displacement field is calculated. Under the action of a thermal stress finite element formulation, the thermal expansion coefficient of each material determines the strain generated by the temperature differential.
Material Properties
Temperature-dependent material properties must be specified to ensure the accuracy of the simulation results. Modulus of elasticity, Poisson’s ratio, and thermal conductivity can vary over the operating temperature range of the assembly. For this reason, engineers use measured values from laboratory testing to populate the material database.
If the material behavior is highly non-linear, elastic-plastic or viscoelastic models must be integrated to capture the stress relaxation over time.
Quality Control
Validation of the simulated results is achieved by comparing computed displacements against measurements from strain gauges or digital image correlation. Discrepancies between the predicted and observed stress distributions indicate that the boundary conditions or material properties require adjustment. Refined mesh density in regions of high stress gradients ensures that the numerical solutions converge to stable values.
