The Thermal Stress Interface
The Thermal Stress () interface combines a Solid Mechanics interface with a Heat Transfer in Solids interface. The coupling occurs on the domain level, where the temperature from the Heat Transfer interface acts as a thermal load for the Solid Mechanics interface, causing thermal expansion.
When a predefined Thermal Stress interface is added from the Structural Mechanics branch () of the Model Wizard or Add Physics windows, Solid Mechanics and Heat Transfer in Solids interfaces are added to the Model Builder.
In addition, the Multiphysics node is added, which automatically includes the multiphysics coupling features Thermal Expansion and Temperature Coupling.
On the Constituent Physics Interfaces
The Solid Mechanics interface is intended for general structural analysis of 3D, 2D, or axisymmetric bodies. In 2D, plane stress or plane strain assumptions can be used. The Solid Mechanics interface is based on solving Navier’s equations, and results such as displacements, stresses, and strains are computed.
The Heat Transfer in Solids interface provides features for modeling heat transfer by conduction, convection, and radiation. A Heat Transfer in Solids model is active by default on all domains. All functionality for including other domain types, such as a fluid domain, is also available. The temperature equation defined in solid domains corresponds to the differential form of the Fourier’s law that may contain additional contributions like heat sources.
In previous versions of COMSOL Multiphysics, a specific physics interface called Thermal Stress was added to the Model Builder. Now, a predefined multiphysics coupling approach is used, improving the flexibility and design options for your modeling. For specific details, see The Multiphysics Node and Multiphysics Modeling Approaches in the COMSOL Multiphysics Reference Manual.
For information about the constitutive equations including thermal expansion in the section dealing with the theory background, see Structural Mechanics Theory.
Settings for Physics Interfaces and Coupling Features
When physics interfaces are added using the predefined couplings, for example Thermal Stress, specific settings are included with the physics interfaces and the coupling features.
However, if physics interfaces are added one at a time, followed by the coupling features, these modified settings are not automatically included.
For example, if single Solid Mechanics and Heat Transfer in Solids interfaces are added, an empty Multiphysics node appears in the model tree. You can choose from the available coupling features but the settings in the constituent interfaces are nor modified.
Coupling features are available from the context menu (right-click the Multiphysics node) or from the Physics toolbar, Multiphysics menu.
Table 10-1: Modified Settings for a Thermal Stress interface
Physics Interface or Coupling Feature
Modified Settings
Solid Mechanics
For the Solid Mechanics interface, under Structural Transient Behavior the Structural transient behavior is set to Quasi-static.
Heat Transfer in Solids
For the Heat Transfer in Solids interface, under Discretization, the shape function order for the temperature is set to Linear.
Thermal Expansion
The Domain Selection is the same as that of the participating physics interfaces.
The corresponding Solid Mechanics and Heat Transfer in Solids interfaces are preselected in the Thermal Expansion section.
Temperature Coupling
The corresponding Solid Mechanics and Heat Transfer in Solids interfaces are preselected in the Temperature Coupling section (described in the COMSOL Multiphysics Reference Manual).
Physics Interfaces and Coupling Features
Use the online help in COMSOL Multiphysics to locate and search all the documentation. All these links also work directly in COMSOL Multiphysics when using the Help system.
Coupling Features
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The Thermal Expansion (Multiphysics Coupling) coupling feature node is described in this section.
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The Temperature Coupling feature node is described for The Joule Heating Interface in the COMSOL Multiphysics Reference Manual.
Fuel Cell Bipolar Plate: Application Library path Structural_Mechanics_Module/Thermal-Structure_Interaction/bipolar_plate
Thermal Expansion in a MEMS Device: Application Library path MEMS_Module/Sensors/thermal_expansion