APPLICATION OF THE NON-CYCLIC METHOD OF SHAKEDOWN ANALYSIS TO PROBLEMS WITH CYCLICALLY MOVING THERMAL STRESS

The non-cyclic method of shakedown analysis allows the entire ratchet boundary to be determined for a given set of monotonic and cyclic loads on a component. The method is based on an extension of the lower bound shakedown theorem. Typically, the loading of interest to shakedown consists of cyclic thermal loading acting in conjunction with cyclic and monotonic (mean) primary loads, such as pressure. To date, a certain class of spatially moving cyclic thermal loads could not be analyzed with numerical implementations of the non-cyclic method. In these cases, the mean thermal load cannot be balanced by a self-equilibrating stress state, and the component can ratchet under a purely thermal load. This paper examines why the restriction on the non-cyclic method and similar other approaches to shakedown analysis exists, and proposes an extension with the help of which an analysis of this class of problems becomes feasible. The method is demonstrated on a number of simple examples