Sometimes MBD analysis can be failed during optimization process. In this case, the conventional optimization tools are crashed. However, AutoDesign overcomes it automatically. AutoDesign regards that design point as a worst cased design shown in Figure 1. This prevents the design process from being crashed, although it can make the meta-models to be ill conditioned. As you know, Kriging method solves a sub-optimization problem to construct meta-models but radial basis functions not. Empirically, Kriging method is more stable results in this case.
Figure 1 Worst cased treatment when the analysis is failed