StressCheck Demo: Thermo-Mechanical Analysis with Temperature-Dependent Material Properties

Abstract: A thermo-mechanical (Heat Transfer -> Elasticity) analysis is performed for a Handbook model of two Inconel 718 connected pipes connected by a thin fin (\Handbook\Tutorial\ConnectedPipes.scw). The parametric Handbook model contains formula-based, temperature-dependent coefficients of thermal conductivity (when the theory is Heat Transfer) as well as formula-based, temperature-dependent linear isotropic material properties (when the theory is Elasticity).

The goals of the thermo-mechanical analysis are to:

• Compute the linear (coefficient of thermal conductivity for a reference temperature T=200 °F) and material nonlinear (coefficient of thermal conductivity is allowed to be temperature-dependent) temperature distributions via steady-state conduction heat transfer
• Apply the temperature distribution computed from the material nonlinear solution as a thermal load for all elements using a reference temperature of 0 °F
• Solve a linear elastic solution using the thermal load, symmetry/rigid body constraints, and temperature-dependent linear isotropic properties
• Extract the local stresses at the intersection of the fin and the pipes.

For the steady-state conduction heat transfer analysis, the following boundary conditions are assigned:

• Cooling of the external pipe surfaces is by convection via parameters “Hc” (convective film coefficient) and  “Tc”(convective temperature).
• The left pipe inside temperature is given by parameter “To”, and the right pipe inside temperature is given by parameter “Tp”.

For the linear elastic analysis, the following boundary conditions are assigned:

• Thermal loading of the connecting pipes + fin is defined by importing the temperatures from the material nonlinear steady state conduction heat transfer solution.
• Double-symmetry conditions are used to model 1/4 of the connecting pipes + fin.
• A nodal constraint in the global X direction restricts rigid body translation.