Thermal stress study

A Thermal Stress study is used to evaluate the stresses induced by some thermal load. For example, will the part warp as a result of some change in temperature? Can the components still be assembled as designed after experiencing the thermal load? Use the Thermal Stress analysis to explore how the stresses from these loads can impact the life of your part.

Temperature gradients in the model and varying thermal expansion characteristics of the materials produce stresses due to nonuniform thermal expansion. The stress is a function of the strain due to thermal expansion/contraction and the material stiffness. In addition, you can apply mechanical loads (such as gravity, pressure, or force) to thermal stress models. The results show you the combined effects of structural load stresses and temperature-induced stresses.

Thermal Contact

When performing a thermal stress analysis on an assembly, it is important that you consider the resistance to heat flow that occurs along contact areas. For thermal analyses, an additional contact setting appears in the Edit Contact dialog:

By default, bonded contact provides perfect conductance of heat from one body to the other (zero resistance). To accurately represent resistance to the flow of heat across a contact interface, you must specify a suitable Thermal Conductance value. For example, heat does not conduct perfectly between a transistor and a heat sink, especially with an electrical insulator included between them. In operation, the transistor contact face is hotter that the heat sink contact face. This phenomenon is not reflected in your thermal results unless you specify a suitable Thermal Conductance value.

Thermal Conductance is inversely proportional to thermal resistance. The lower the conductance, the higher the resistance to the flow of heat. The greater the resistance to heat flow, the greater the temperature difference across the contact interface.

Supported Contact Types

All Contact types except Free contacts are supported for Thermal stress analyses:

• Bonded
• Offset Bonded
• Separation
• Sliding
• Rough

Thermal Stress Analysis Requirements

This type of analysis requires:

• The loads and constraints are independent of time. Steady-state means that the solution can be considered after an infinite amount of time has passed.
• A heat source and sink must be defined. If there is only a source and no means to remove heat, the temperature of the model would be infinite. Conservation of energy must be observed, energy in must be equal to energy out.
• At least one temperature-based thermal load is required to provide a reference temperature. A temperature profile can not be calculated across a part with 5 W into one side and 5 W out another side. A reference temperature is needed to provide the temperature profile.

Thermal Stress analysis examples

The following list contains a couple examples for which a Thermal Stress analysis might be appropriate:

• Electronics
• Automotive Parts

The results produced by a Thermal Stress study are a combination of the results produced in the Static Stress and Thermal study types.