Finite Element modeling of force amplification at the spindle due to a tire's cavity mode: experimental verification

Reduction of tire-road noise is an important issue when developing luxury cars and electric vehicles. In this context, the air-cavity mode is an important source of spindle forces transmitted to the suspension that then increase interior noise levels. When a tire rotates, the cavity mode near 200 Hz splits into two adjacent modes due to a Doppler effect and tire deformation. That split can lead to increased levels of both longitudinal and vertical spindle forces at the spindle since the two acoustic modes each contribute to both forces when the tire rotates. Thus, it is important to develop tools to identify the contributions of the split air-cavity modes to the spindle force. A FE simulation of the spindle force for a steady-state rolling has been verified by a comparison with laboratory test results obtained by using a wheel-force transducer mounted on Purdue's Tire Pavement Test Apparatus. It was observed that the frequency split expands as the rotation speed increases and that the vertical spindle force increases when aligned with an odd-numbered circumferential structural mode. By using the correlated simulation model, parametric studies have been carried out focused on minimizing the vertical spindle force due to air-cavity mode near 200 Hz.