The Thermoelasticity Interface
The Thermoelasticity (te) interface (), found under the Structural Mechanics branch () when adding a physics interface, adds thermoelastic coupling terms to the Solid Mechanics interface and solves for the resulting temperature deviation in addition to the structural displacements. The thermoelastic coupling results in local cooling of material under tension and heating of material that is compressed. Irreversible heat transfer occurs between the warm and cool regions of the solid producing mechanical losses, which can be important, particularly for small structures.
When this physics interface is added, the following default nodes are also added to the Model Builder—Linear Thermoelastic Material, Thermal Insulation, Free, and Initial Values. Then, from the Physics toolbar, add other nodes that implement, for example, loads, constraints, and material models for the solid domain. You can also right-click Thermoelasticity to select physics features from the context menu.
Settings
The Label is the default physics interface name.
The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.
The default Name (for the first physics interface in the model) is te.
2D Approximation
From the 2D approximation list select Plane stress or Plane strain. Plane strain is appropriate when the strain in the structure is uniform in the out of plane direction, for example when the structure is very thick in the out of plane direction. Plane stress is appropriate when the out of plane stress can be neglected, for example for a structure that is very thin in the out of plane direction, such that the out of plane stress is negligible. When modeling using plane stress, the physics interface solves for the out-of-plane strain components in addition to the displacement field u.
Thickness
For 2D components, enter a value or expression for the Thickness d (SI unit: m). The default value of 1 m is suitable for plane strain models, where it represents a a unit-depth slice, for example. For plane stress models, enter the actual thickness, which should be small compared to the size of the plate for the plane stress assumption to be valid.
In rare cases, when thickness is changed in parts of the geometry; then use the Change Thickness feature. This thickness also controls the thickness dz, active in the separate Heat Transfer interface for 2D out-of-plane heat transfer.
Structural Transient Behavior
From the Structural transient behavior list, select Include inertial terms (the default) or Quasi-static. Use Quasi-static to treat the elastic behavior as quasi-static (with no mass effects; that is, no second-order time derivatives). Selecting this option gives a more efficient solution for problems where the variation in time is slow when compared to the natural frequencies of the system. The default solver for the time stepping is changed from Generalized alpha to BDF when Quasi-static is selected.
Reference Point for Moment Computation
Enter the coordinates of the Reference point for moment computation xref (SI unit: m). The resulting moments (applied or as reactions) are then computed relative to this reference point. During the results and analysis stage, the coordinates can be changed in the Parameters section in the result nodes.
Typical Wave Speed
The typical wave speed cref is a parameter for the perfectly matched layers (PMLs) if used in a solid wave propagation model. The default value is te.cp, the pressure-wave speed. If you want to use another wave speed, enter a value or expression in the Typical wave speed for perfectly matched layers field.
Dependent Variables
The dependent variables (field variables) are the Displacement field u and its components, and the Temperature variation T. The names can be changed but the names of fields and dependent variables must be unique within a model.
Discretization
To display this section, click the Show button () and select Discretization.
Select an Element type—Mixed order (the default) or Equal order. Mixed order means that the physics interface uses shape functions that are one order higher for the displacements than for the temperature. Select U1+T1, U2+T1 (the default), U3+T2, or U4+T3 for the Thermal stress fields for mixed-order elements or the corresponding element-order combinations for equal-order elements. U2+T1, for example, means second-order elements for the displacements and first-order elements for the temperature. See Common Physics Interface and Feature Settings and Nodes for links to more information.
•
Common Physics Interface and Feature Settings and Nodes
•
Domain, Boundary, Edge, Point, and Pair Nodes for the Thermoelasticity Interface
•
Theory for the Thermoelasticity Interface