Energy dissipation under thermomechanical fatigue loading

The paper presents a numerical approach to compute the total amount of dissipated energy under arbitrary rate independent uniaxial thermomechanical fatigue (TMF) loading. Such an approach is based on the stress controlled Prandtl type operator enabling continuous energy dissipation calculation. It focuses on non-isothermal stress–strain conditions of a spring–slider segment, and relates slider movements to irreversible energy dissipation. The correct amount of dissipated energy is computed at any moment (online), without the need of ‘waiting’ the cycle to finish. The operator approach guaranties monotonically increasing progress of energy dissipation, which is within the framework of thermodynamics. It is also shown that the operator approach results in the same dissipated energy after closed isothermal cycle as the traditional integration approach.

► The Prandtl type operator is used to determine dissipated energy. ► Key equations of the operator approach are introduced. ► Operator approach is compared to the traditional integration approach by simulations. ► Both approaches give the same dissipated energy after a closed cycle. ► The operator approach can be used under arbitrary rate independent TMF loading.