APPROXIMATE METHOD FOR THE ANALYSIS OF COMPONENTS UNDERGOING RATCHETTING AND FAILURE

An approximate method has been presented for the design analysis of en gineering components subjected to combined cyclic thermal and mechanic al loading. The method is based on the discretization of components us ing multibar modelling which enables the effects of stress redistribut ion to be included as creep and cyclic plasticity damage evolves. Cycl e jumping methods have also been presented which extend previous metho ds to handle problems in which incremental plastic straining (ratchett ing) occurs. Cycle jumping leads to considerable reductions in compute r CPU (central processing unit) resources, and this has been shown for a range of loading conditions. The cycle jumping technique has been u tilized to analyse the ratchetting behaviour of a multibar structure s elected to model geometrical and thermomechanical effects typically en countered in practical design situations. The method has been used to predict the behaviour of a component when subjected to cyclic thermal loading, and the results compared with those obtained from detailed fi nite element analysis. The method is also used to analyse the same com ponent when subjected to constant mechanical loading, in addition to c yclic thermal loading leading to ratchetting. The important features o f the two analyses are then compared. In this way, the multibar modell ing is shown to enable the computationally efficient analysis of engin eering components.