IMPROVED APPROACHES TO THE MEASUREMENT AND ANALYSIS OF TORSIONAL VIBRATION ANALYSIS

A primary goal of NVH engineering is the identificationand control of noise and vibration sources. In recentyears the torsional vibration behaviour of engine and powertrain components has gained in significance. This paper discusses several aspects of measuring and analysing torsional vibration and related data. Several torsional vibration measurement techniques are presented, together with remarks on precautions against possible sources of error, and the order of accuracy to be expected of the test results. Two applications requiring multichannel measurement and analysis are outlined.

MEASUREMENT AND ANALYSIS OF TORSIONAL VIBRATIONS IN AUTOMOTIVE DEVELOPMENT

Torsional and rotational vibrations are mechanical vibrations caused by time-alternating torques which are superimposed on the otherwise steady running speed of a rotating shaft. In automotive engineering torsional vibration is primarily caused by the fluctuations in engine power output. This results in crankshaft angular velocity fluctuations which cause twisting and untwisting of the shaft. The effects of torsional vibration are amplified by torsional resonance which occurs when a shaft‘s natural frequency coincides with its torsional frequency. Excessive torsional vibrations can result in unwanted noise, powertrain component wear and, in severe cases, broken shafts. To identify such effects in advance and adopt measures to avoid them before ex-cessive damage has occurred, the development engineer requires dedicated, state-of-the-art measuring equipment incorporating application-specific software to simplify measurement setup and provide quick analysis.