UC Berkeley

The primary notion of hybrid simulation is to only test part of a system physically and to simulate the rest in a computer. While this basic idea is simple to understand, there is surprisingly little theoretical work targeted towards understanding the behavior of the concept, and in particular, its theoretical limitations. In this work we present an initial investigation of the theoretical limitations of hybrid testing in the context of two canonical settings: a beam and a plate. In each case, we mathematically split the physical system into two pieces whose motion we derive in closed-form. At the splitting interface we introduce theoretical models associated with tracking and phase error of the boundary motions and forces. We are able to demonstrate that such systems are generally viable only below the first fundamental frequency of the system. Furthermore, we show there is a tendency to accumulate global errors, relative to the classical solutions, at the slightest introduction of any interface matching error but that these errors are mostly insensitive to further increase in mismatch. Finally, it is found that the different substructures of the systems are subject to excitation at their own independent natural frequencies in addition to those of the hybrid system.