Time-dependence of the threshold function in the perfect plasticity model

This paper discusses the time-dependence of the threshold function in the perfect plasticity model. In physical terms, it is natural that the threshold function depends on some unknown variable. Therefore, it is meaningful to discuss the well-posedness of this function under the weaker assumption of time-dependence. Time-dependence is also interesting from the viewpoint of the abstract evolution equation. To prove the existence of a solution to the perfect plasticity model, the recent abstract theory under the continuous class with respect to time is used.