N&V Performance of GFR Composite Powertrain Brackets Using Vehicle Simulation Models

Vehicle weight reduction is important to improve the fuel mileage of Internal Combustion Engine (ICE) vehicles and to extend the range of Electric Vehicles (EVs). Glass Fiber Reinforced (GFR) Composite (Polyamide) brackets provide significant weight reductions at a competitive part price. Traditionally, metal brackets are designed to surpass a target natural frequency and static stiffness. Composite brackets are inherently less stiff and have lower natural frequencies. However, composite brackets also have higher material damping than metal brackets, and good isolation performance can be achieved. The key to integrating composite brackets into the vehicle design is to perform adequate analysis to ensure that the noise and vibration performance at the vehicle level meets expectations. In this paper, case studies are presented for two different vehicles – a Clevis bracket for an IC Engine vehicle, and an electric motor mount bracket. For each case, measurement data is used to develop simulator models for the vehicles with the traditional metal brackets as well as the composite brackets, and the models are used to make a comparative evaluation of passenger noise for different driving conditions.