Perry Gu

Sound and vibration perceptual contributions during vehicle transient and steady-state road inputs

This paper discusses two studies which address the perception of both transient and steady state sound and vibration experienced by drivers in vehicles. While past studies with railway and aircraft sound and vibration showed varying degrees of sound and vibration interaction, the results of these two studies showed little evidence of interaction. Additionally, both sound and vibration appeared to contribute about equally to the overall NVH perception. Other researchers have observed that the strongest modality tends to dominate perception, but that effect was not observed in the studies presented here.

A New Experimental Methodology to Estimate Chassis Force Transmissibility and Applications to Road NVH Improvement

The performance of structure-borne road NVH can be cascaded down to three major systems: 1) vehicle body structure, 2) chassis/suspension, 3) tire/wheel. The forces at the body attachment points are controlled by the isolation efficiency of the chassis/suspension system and the excitation at the spindle/knuckle due to the tire/road interaction. The chassis force transmissibility is a metric to quantify the isolation efficiency. This paper presents a new experimental methodology to estimate the chassis force transmissibility from a fully assembled vehicle. For the calculation of the transmissibility, the spindle force/moment estimation and the conventional Noise Path Analysis (NPA) methodologies are utilized. A merit of the methodology provides not only spindle force to body force transmissibility but also spindle moment to body force transmissibility. Hence it enables us to understand the effectiveness of the spindle moments on the body forces. The feasibility and applicability of the methodology was experimentally demonstrated. The accuracy of the methodology was verified. This methodology can be used for the benchmarking and system cascading for target setting to achieve a desired road NVH performance as well as for diagnosing root causes in the problem solving procedure. Two different vehicles were used for the demonstration of the root cause analysis implementing the method. The comparison of the chassis force transmissibility of these two vehicles is presented to show the merits of this methodology.

A New Experimental Methodology to Estimate Tire/Wheel Blocked Force for Road NVH Application

Past studies have shown that NVH CAE tire model quality is not adequate to correctly capture a mid-frequency range (100-300 Hz). A new methodology has been developed to estimate tire forces that are independent of dynamic characteristics of vehicle suspension and rig test fixture. The forces are called tire blocked forces and defined as a force generated by a tire/wheel system whose boundary condition is constrained. The tire blocked force is estimated by removing the dynamic effect of the tire force measurement fixture. The blocked forces can be applied to CAE models to predict vehicle road NVH responses. This new method can also be used as a target setting tool. Tire suppliers can check the blocked tire forces from the rig testing data against a force target before they submit tires to automotive manufacturers for evaluations on a prototype vehicle.