Vibra-Acoustic Characteristic Matching of Mini-Car Body Structure and Interior Acoustic Cavity in Low Frequency Range

Abstract

This paper focused on the interior boom noise of a mini-car when driving at high speeds. Vehicle interior noise rotor drum tests in semi-anechoic room showed that vehicle interior boom noise in narrow frequency band exited near 250Hz. Structural and acoustic finite element analysis certified the front roof and rear floor coupled with interior acoustic cavity around this frequency, causing acoustic cavity resonance. On the base of sensitivity analysis technology, a structural improvement schemes pasting free damping fin on the front roof and rear floor of mini-car body for vibration and noise reduction was proposed. Finite element Modal analysis of the mini-car body after improving indicated that local modal amplitude of the mini-car body at the front roof and rear floor around 250Hz was controlled effectively. Mini-car rotating drum test results after improving showed that vehicle interior boom noise was decreased obviously after pasting free damping fin at the front roof and rear floor. The improving schemes and noise reduction effects proposed in this paper were validated.