S–T
Thermal–mechanical
Differential expansion is a load. A temperature field that was treated as a fixed boundary moves the stress concentration, and a deforming contact can move the heat path back. We couple them when life, leak, or residual shape is the decision. One-way if the geometry barely changes. Staggered, or monolithic, if a gap or a contact depends on temperature.
Typical hardware. Turbine disks, weld distortion, press fits, exhaust hardware.