Observability of HIP nonlinear dynamics

The observability of the nonlinear system equations describing the hot isostatic pressing (HIP´ing) dynamic system is investigated. HIP´ing is a process for consolidating porous materials to high density. The feasibility of estimating a particular state (grain size) of the HIP nonlinear system dynamics from measurements of the system´s output (density) and input (applied temperature and applied pressure) is examined. The problem is treated as an observability issue in which it is desired to determine whether knowledge of the input/output data for the HIP´ing process can uniquely determine the states of the system. If the system is observable, then grain size can be estimated during the HIP´ing process without directly measuring it as an output of the system. The results indicate that the system is observable