Modal contribution index of subsystems for studying vibration countermeasures of a whole structure

Abstract

When designing NVH (Noise, Vibration and Harshness) performance for complex structures such as automobiles, trains, and aircraft, it is rare to target all components of the whole structure and the subsystem be designed are often fixed. In recent years, the kernel Compliance Analysis (kCA) method has been proposed as a method for designing NVH performance by dividing a whole structure into two subsystems. When modifying the structure of the subsystem to be designed by using the kCA, it is an important index which mode of the subsystem has a large contribution to the resonance of a whole structure. However, in the conventional sensitivity of structural modification, only those that determine the contribution of the subsystem for each mode of a whole structure are found. This paper, therefore, derives a new index for understanding the relative importance of the modes of subsystems to the resonance of a whole structure. As the index is derived based on the kCA, it has good compatibility with the design of NVH performance by the kCA. After derivation of the index, the effectiveness of the index will be verified through a numerical example of the resonance assignment of a whole structure combined with the kCA.

Keywords

• modal analysis
• resonance
• substructuring
• pole assignment
• modal contribution factor