TECHNIQUES FOR MOVEMENT DECOMPOSITION OF COMPLEX VIBRATION OF VEHICLE BODY, SYSTEMS AND COMPONENTS

摘要

Vehicle body and components (body structure, doors, hood, tailgate, mirrors, etc) are rigidlyrnwelded or attached to the vehicle body by means of articulated elements that allow a highrnlevel of mobility. In the latter case, for example, this may cause poor vibration performance ofrnthe part when exposed to oscillating loads such as the ones produced by the engine, the roadrnirregularities and the aerodynamic forces. The poor vibration performance of a closure, forrnexample, affects comfort perception and can cause squeak and rattle or lead to a high level ofrnwind noise inside the vehicle. The problems associated with small displacements of thesernparts during driving conditions can be analysed using signal processing in both the time andrnthe frequency domain. Also, from a practical point of view, the investigation of the relativernmovement of these elements with respect to the body shows a great potential for problemrnsolving.rnThis paper presents case-studies based on the application of experimental methods forrnanalysing the in-service movement of body parts, closures and vehicle parts using time andrnfrequency domain signal processing in combination with geometrical equations that define thern‘spatial relationship’ between the measured points. These methods of analysis define thernabsolute and relative dynamic behaviour of these parts with respect to the vehicle body. It isrnshown that these methodologies are of particular interest in defining countermeasures torncontrol the in-service displacements of any vehicle part and thus the information provided isrnof high interest for fatigue, NVH or comfort analysis.