Modal analysis of the washing machine heater

Abstract

The paper deals with the assessment of the modal parameters of the washing machine heater. At first, a numerical modal analysis based on a finite element method of the heater was performed. Consequently, the experimental modal analysis of the heater was realised to verify the finite element model. As the heater’s shape and dimensions do not allow modal parameters estimation using conventional gages of acceleration, two optical approaches were applied. In both cases, the excitation was realised using Bruel&Kjaer 8206 impact hammer. In the first one, the responses of the heater were captured by Polytec PDV-100 vibrometer, which principle is based on laser Doppler vibrometry. Such a type of device allows capturing of responses in a form of velocity only in the direction of observation. To observe the responses in three mutually perpendicular directions the high-speed digital image correlation system Q-450 Dantec Dynamics was used. Mentioned correlation system uses for the full-field measurement of displacements precise digital cameras with high image resolution. As it is not adapted for modal parameters estimation, the additional software DICMAN 3D, developed at the authors’ workplace, was used. DICMAN 3D allows evaluation of a single-reference as well as a multi-reference measurement in space and for automatic estimation of natural frequencies and damping ratios comprises an advanced estimation module with several algorithms. Finally, the influence of the temperature on the modal parameters was investigated using the finite element model of the heater.The paper deals with the assessment of the modal parameters of the washing machine heater. At first, a numerical modal analysis based on a finite element method of the heater was performed. Consequently, the experimental modal analysis of the heater was realised to verify the finite element model. As the heater’s shape and dimensions do not allow modal parameters estimation using conventional gages of acceleration, two optical approaches were applied. In both cases, the excitation was realised using Bruel&Kjaer 8206 impact hammer. In the first one, the responses of the heater were captured by Polytec PDV-100 vibrometer, which principle is based on laser Doppler vibrometry. Such a type of device allows capturing of responses in a form of velocity only in the direction of observation. To observe the responses in three mutually perpendicular directions the high-speed digital image correlation system Q-450 Dantec Dynamics was used. Mentioned correlation system uses for the full-field measurement of displaceme...