LOAD SICKNESS TREATMENT IN TOPOLOGY OPTIMIZATION OF CONTINUUM STRUCTURE BY ICM METHOD WITH STRESS GLOBALIZATION

Because the load case is often very complicated in the topology optimization of continuum structures, there is a phenomenon of the load sickness that likes stiffness sickness in the structural analysis. The reason caused the load sickness is that most algorithms of the topology optimization have not considered different influences between the loads with small forces and the loads with big forces. Therefore, some of topology paths of transferring small forces may disappear during iterative process. This paper dissects the phenomenon of the load sickness and classifies the phenomenon into three cases: 1) load sickness exists between load cases, but not within each load case; 2) load sickness exists within some load cases; 3) load sickness exists not only between load cases, but also within some load cases. To deal with problem of load sickness, a strategy based on strain energy is put forward, using ICM method with stress globalization, the problems of above three cases of load sickness are solved by adopting different complementary approaches one by one. For topology optimization with stress constraints under multiple load cases, the stress globalization means that local stress constraints are transformed into global energy constraints based on the fourth strength criterion. Several numerical examples reveal that the topology paths of transferring forces can be obtained more easily by substituting global strain energy constraints for local stresses constraints, and the problem of load sickness can be dealt with more conveniently.