Tech Briefs

Thermo-Mechanical Coupling (TMC) Analysis of a Rubber Pad

The animation shows a simplified model of a rubber pad heating up due to viscoelastic dissipation. The problem was solved using ADINA version 8.2.

In the structural model, the pad is modeled using the Ogden material model with additional viscoelastic effects. In the thermal model, the pad is modeled with a constant thermal conductivity and specific heat, with convection on the free edges of the pad. Initially the pad is at 25 degrees C.

The pad is preloaded by displacing the top of the pad over a period of 2 seconds. The rate of loading is slow enough so that no viscoelastic effects are present. Then the top of the pad is sinusoidally displaced at 100 cycles/second for 5 seconds. This loading induces viscoelastic stresses, which have the following effects:

- The viscoelastic stresses cause dissipation, the dissipation causes internal heat generation, and the internal heat generation causes the temperature of the pad to increase to about 43.5 degrees C. The animation shows the fluctuation of internal heat generation during one cycle of loading.

- The temperature increase affects the viscoelastic response through time-temperature superposition. The time-temperature superposition causes the effective viscoelastic relaxation time to decrease. This causes the viscoelastic effects to decrease as the temperature increases, so that the force-deflection curve shows less hysteresis and the heat generation rate decreases. These effects are shown in the following graphs.