Investigation on similarity laws for dynamic properties of presses
Experimental and numerical analyses on transferability of modal parameters
The present paper deals with the experimental investigation of dynamic similarity laws of technical structures based on modal analyses of a reference and a scaled servo-screw press. At first, a brief introduction into the theoretical background is given and similarity principles for mechanical systems and used modal global and local correlation criteria are explained. After the description of the measurement setup and its evaluation, a comparison of the reference and the scaled press is carried out. The comparison is based on modal parameters obtained by experimental modal analysis where different data acquisition methods are used. For the reference press, frequency response functions (FRF) are obtained by impact hammer and acceleration sensors and for the scaled press by electrodynamic shaker and a laser scanning vibrometer. The acquired FRF's are basis for the following curve fitting process to determine the modal parameters of both systems. Subsequently, the derivation of scale factors from modal parameters is characterized using eigenvalue and eigenvector related correlation criteria. The impact of different slide positions as well as the influence of various contact conditions between slide and frame on the scaling factors are analyzed and discussed. The investigation of slide position and contact condition influences are carried out using the obtained experimental modal parameters in combination with linear-elastic finite element models.