Evaluation of Acoustic Performance of Expandable Foam Baffles and Correlation with Incab Noise

Baffle plates with heat reactive expandable foam sealants have increasingly found their applications in automotives. They are used to separate body cavities and to impede noise, water and dust propagation inside of body cavities, thus control noise intrusion into the passenger compartment. Use of these sealant materials has grown significantly as the demands to improve vehicle acoustic performance has increased. Traditionally quantification of the acoustic performance of expandable baffle samples involved making separate vehicles with and without expandable baffles and measure the incab noise to know the effect. The absolute acoustic evaluation of the baffles is very difficult as number of other vehicle parameters is also responsible for vehicle incab noise. Also, it is a time consuming and a costly method to evaluate. The noise reduction across the baffles can not be measured as there is no access once the vehicle is build, because it is fitted in closed sections like sill, cant rail and pillars. The noise reduction evaluation set up at rig level is developed for relative comparisons and faster evaluation of the expandable baffles prior to BIW design. This paper presents a step in the progression for evaluating the acoustic performance of the expandable baffles both in the vehicle level as well as in the rig level and their correlation. These experiments use standard testing procedures for evaluating the baffles. Baffles with different designs and suppliers were evaluated during the process. The optimized sample and supplier from cost and performance point of view is recommended for implementation. This exercise has also helped to study the quality and consistency of the material supplied for the production. It was also understood that rig level evaluation of the expandable baffles can minimize the vehicle level tests.