Force identification using a statically completed reduced model deriving from tests

Predicting the operating behaviour of a complex assembly including active components is a challenge, since accurate models of those components are rarely available. For example, the dynamic effects of coupled motor pumps on a nuclear power plant floor are of critical interest, but difficult to predict at the design phase. Indeed, manufacturers do not provide a description of the internal behaviour of the pump, and fluid models can be hard to handle in order to properly define the internal loads. However, the real device and a FE model of the relevant part of the plant are available, and test facilities can be designed. s paper, a complete methodology is described to set up a statically complete reduced model of an active component from tests only. This active component is submitted to an internal load. For both the component and the load, no model is available. However, one may need to estimate the behaviour and effects of this component when linked to another structure. First, a statically complete dynamic model of the active component is set up, using a test device reproducing the joints between the active component and the target structure. The use of data expansion techniques on a coarse FE model of the active component, coupled with a tuned FE model of the test device allows the estimation of the residual flexibilities on the interface. Next, a component-dependent equivalent load is identified. Then, test and FE models are combined to compute the forces to apply on the target structure. rical example illustrates the methodology and highlights its practical implementation. Good results are obtained with realistic simulation data. The results also illustrate practical difficulties and limitations.