Abstract
A Transfer path analysis (TPA) is undertaken for a car subframe concerning six DOF of freedom and two coupling points up to 500 Hz. Integrated stingers have been developed to improve measurement results. The relative importance of the rotational components is investigated. The blocked impedance method has been used to couple the subframe to the car body using measured mobilities via two isolators out of four. The sound sensitivity is measured directly for the coupled system and compared with the total sum of the calculated transfer path components which are calculated with measured mobilities and transfer functions. Calculated and measured results show good agreement. The importance of the rotational paths depends on the characteristics of the isolator and the structures where it is mounted. It was found that the front mount position is more sensitive to rotations compared to the rear mount position. The rear mount position is also a much stiffer construction. It was found that above 220 Hz, the rotational paths are of the same importance as the translational paths when both points were connected to the body frame. It was also found that for the rear mount position, only one translational transfer path dominates. These conclusions do not differ especially for different excitation directions at the engine mount position.
