SICODYN international benchmark on dynamic analysis of structure assemblies: variability and numerical-experimental correlation on an industrial pump

A benchmark is organised to quantify the variability relative to structure dynamics computations. The chosen demonstrator is a pump in service in thermal central units, which is an engineered system with not well-known parameters, considered in its work environment. The blind modal characterisation of the separate pump components shows a 5%-12% variability on eigenfrequency values and a less than 15% frequency error in comparison with experimental values. The numerical-experimental MAC numbers reach 0.7 at the maximum, even after updating. An example of modal results on the pump assembly fixed is presented, which shows a larger discrepancy with measurement values, essentially due to the modelling of the interfaces and boundary condition, and to the possible simplification of the main components F.E. models to reduce their size. Though a significant frequency error, the first overall modes are correctly identified. If this tendency can be confirmed from all the participants' results, the conclusion to be drawn is that, if the predictive capability of F.E. models to represent the dynamical behaviour of sub-structures is satisfactory, the one relative to structures that are built-up of several components does not allow their confident use. Additional information issued from measurements is needed to improve their accuracy.