Optimization of Local Stiffness for Reducing Off-Highway Machinery Interior Noise

It is common for automotive manufacturers and off-highway machinery manufacturers to gain insight into the system’s structural dynamics by evaluating the system inertance functions near the mount locations. The acoustic response of the operator’s ears is a function of the vibro-acoustic characteristics of the system structural dynamics interacting with the cavity, with the actual load applied at the mount locations. The overall vibro-acoustic characteristics can be influenced by a change in local stiffness. To analyze the response of a system, it is necessary to go beyond analyzing its transfer functions. The actual load needs to be understood and applied to the transfer function set. Finite element (FE) based analysis provides a good foundation for deterministic solutions. However the finite element method decreases in accuracy as frequency increases. Many NVH problems happen to be at the mid frequency range where solving the problem with the FE-only approach falls short [1]. This project utilizes the high definition nature of test-based frequency response function for the main structure, the flexibility of FE-based FRF synthesis for the body attachments, in conjunction with the inverse force estimation technique to address a fluid-borne noise problem in the mid frequency range. Various design options of body attachment are to be evaluated numerically to reduce interior noise at the operator’s ears.