First 3D Scanning Laser Vibrometer Measurement Successfully Performed
In November, a vibration measurement of an electrical machine was performed with a 3D scanning laser vibrometer in the test field of the IEM for the first time. The measurements were performed within the research project “Concept ELV2” (BMWi: 01MY17002B) and in cooperation with the company Polytec. Compared to conventional measurement methods for noise vibration and harshness (NVH) analysis of electrical machines, optical laser vibrometry enables the validation of calculation models in the entire audible frequency range.
The acoustic behaviour of electrical machines, especially for automotive applications, is an important design criterion. In order to validate the latest developed calculation methods for noise and vibration analysis of electrical machines, the demands on the measurement technology used are constantly increasing.
Conventional measurement technology, such as acceleration sensors, reach their limits in the higher frequency range (e. g. >5 kHz) due to the limited number of measurement points and the associated spatial resolution of the measurement. If the number of applied sensors is increased, the influence of the sensors on the vibration behaviour cannot be neglected.
Current scanning laser vibrometers make it possible to overcome this limit. The optical measuring method, which is based on the Doppler effect, enables a completely feedback-free measurement of the vibration behaviour. The 3D scanning laser vibrometer by Polytec enables, on the one hand, a three-dimensional measurement of the vibration through triangulation of three conventional one-dimensional scanning laser vibrometers and, on the other hand, an FE mesh-precise spatial scanning of the electrical machine.
Modal analysis and operating vibration measurements were performed with this system. The vibration behaviour was measured and analysed at several thousand points. The knowledge gained is used in the development and expansion of models for NVH analysis of electrical machines.