Frequency Optimization Technique Based on the Anti-Resonance Sensitivity Method

There are two analytical methods for optimizing automotive structural dynamic characteristics to improve vehicle ride quality and minimize structural mass for improved fuel economy. The first method, the traditional approach, is to move the undesired structural resonant frequencies out of the range of the forcing functions by modifying the mass and stiffness parameters appropriately. However, in some cases the resonant frequencies are insensitive to parameters; these cases normally are difficult to improve.

Fortunately, there is a second method, based on the natural phenomena that an anti-resonance exists for each resonant frequency. Furthermore, the sensitivity of these anti-resonance nodes to the structural parameters of mass, stiffness and damping are uniquely different. It is this difference in sensitivity that permits cases to be solved, which resist solution by the traditional first method. This alternative method, based on merging the resonant and anti-resonant peaks, results in a mutual coincident which minimizes and/or eliminates the unwanted response, rather than moving it out of the range of operation. This method is described and application examples are given in this paper. ¹