An acoustic target setting and cascading method for vehicle trim part design 2019-01-1581

The first concern in the vehicle trim part design may be its acoustic targets, which are generally defined by absorption area or coefficients, transmission loss (STL) or insertion loss (SIL). The acoustic target break down or cascading in vehicle design is referred to as the process to decide the trim part acoustic targets so as to guaranty the whole vehicle acoustic performance. In many cases, these targets are decided by experience or even subjective evaluation. Simulation based transfer path analysis (TPA), which trace the energy flow from source, through a set of paths, to a given receiver, provides another solution of this problem. Inspired by TPA, this paper proposes a component level target setting method based on the statistical energy analysis (SEA), which is recognized as an efficient method for vehicle NVH analysis in mid and high frequencies. By a validated SEA model for the object vehicle, the contributions of common noise sources and paths, which are generally defined as portions of sheet-metal with trim parts attached, can be calculated. The interior noise level with various possible sound packages is then predictable. On the base of this, acoustic target setting of trim parts can be defined as the solution of a mathematical optimization problem. The targets of trim parts like SIL at certain frequency are taken as design parameters, and the vehicle level performance like the SPL at driver’s ear is incorporated into constraint functions. The method is versatile, which is suitable for traditional ICE vehicles and modern EVs. It can be used on a vehicle prototype for target cascading, or on an existing model for NVH improvement. Several cases and examples on this target setting method have been discussed in the paper.