Impact forces occurring in a forced damped multi-body system with clearances

Abstract

The purpose of this paper is to study the effect of clearance and other parameters on the maximal impact forces likely to occur in a forced multi-body system. Numerical simulations are performed for a large range of parameters. The numerical results showed three regions. In the first one, there is no contact between the bodies. The second one, defined as the smooth region, is characterized by regular evolution with a concentration of the impact forces at the boundaries. In the last one, where the most important impact forces are met, the system shows chaotic behaviours and coincides with the lower values of clearance. Theoretical upper bounds for the maximal forces are proposed and compared to numerical results. In the smooth region, the criterion is respected, but in the chaotic region, some discrepancies are observed. Nevertheless, the criterion gives a good estimation. The dimensionless analysis showed that the maximal impact force is proportional to the mass, the acceleration, the stiffness ratio and the inverse of the damping ratio.

Numerical implementation and validation of a porous approach for fluid–structure interaction applied to pressurized water reactors fuel assemblies under axial water flow and dynamic excitation

“…Based on this model, simulations showed that the bypasses strongly modify the behavior of a fuel assembly 23 and of a row of fuel assemblies 24 . The bypasses also have an effect on the structure, creating strong nonlinear effects with impact 25 …”