Effect of Excitation Methods on Experimental Modal Analysis of Passenger Car Tire

摘要

Tire modal performance plays an important role in passenger car NVH refinement which includes road induced noise. Work done in the past, enumerates testing methods, excitation technique applied and boundary conditions. It also includes Mode shapes, analysis results and study of variables affecting the modal performance of passenger car Tire. Here, in this paper an attempt is made to compare the experimental modal analysis results, obtained using two different excitation techniques for exciting tire. In the experimental modal analysis under discussion, the passenger car tire of type 175/65R14, was inflated up to 2.2 bar (32psi) pressure in free-free condition. Impact Hammer and Electro-dynamic shaker were used to excite the tire structure in radial direction. Single Input Multiple Output technique was used for excitation and response signal acquisition. Modal parameters of the tested tire were identified in the frequency domain with curve fitting technique and modal parameter estimation technique. In-plane, circumferential mode shape, frequencies and modal damping were compared. First acoustic air cavity mode of tire was calculated theoretically and compared with the experimental results obtained from both excitation techniques. In the conducted experiments, the air cavity mode response and damping compared in both excitation methods and concluded that until first air cavity mode and at low frequencies below air cavity mode, it was immaterial whether, the excitation is by impact hammer or electro-dynamic shaker. Better results were obtained with electro-dynamic shaker above the first acoustic air cavity mode compared with hammer excitation.