Transmission of vibrations from the engine to the car body

Vibrations have become an important factor of vehicles. Vibration tests help identify, and then tune the automotive vehicle to improve the structural strength. Due to the increasing development of vehicles and machines and their widespread use. Increased research-using vibrations due to their low or zero interference with the vehicle under test. Vibration testing is often carried out using Laser Doppler Vibrometry (LDV), a device that is used for contactless measurement of vibration on the surface. The laser beam is directed from the device to the surface of interest, and the amplitude and frequency of vibration are extracted from the Doppler shift frequency of the reflected laser beam due to the movement surface. High values of vibration transmitted from the engine, and the way significantly affect the body of the vehicle and the driver. Article presents results of research carried out on vehicles powered by three different engines and rpm. Tests were carried out on an engine dynamometer in the same environmental conditions. Two of engines were with spark ignition, including one with a supercharged engine and compression ignition engine. The measurements were made using the Laser Doppler Vibrometry using Fast Fourier Transform. The spectrum obtained is used for further analysis to determine the acceleration level at various frequencies. Obtained from Fast Fourier Transform readings used for drawing graphs of frequency V acceleration. The results of the study are interesting and promising, as they show a significant difference in the velocity for spark ignition engines and compression-ignition