Efficient dynamic machine structure modelling for high performance dry grinding

Abstract

Accurate finite element machine modelling is typically connected with high computational costs. For this reason, machine structures are usually simplified or analysed only partially. In this paper, an efficient machine modelling technique is presented. It makes use of modal condensation and Krylov subspace model order reduction techniques for Finite-Element-models and Fourier element coupling for moving interfaces. The resulting model is stated to be accurate statically and below a definable frequency. Especially the benefit of having an accurate low order static and dynamic machine model for grinding machine and process simulation is outlined. This enables a full size transient simulation without simplification or omission of potentially important machine components. The modelling methodology is applied to a large and complex test rig for high performance dry grinding. This test rig is used to emulate the railway grinding process, where low frequency deviations are acoustically most relevant. In order to be later used for transient grinding simulations, all test rig components are modelled and assembled. For the validation of the model, its modes and mode-shapes are compared to the results of an experimental modal analysis performed on the real test rig. TCP frequency response functions are further compared between measurement and simulation. The potential use of the model for surface roughness and waviness simulations is shortly implied.