A high mileage vehicle body joint degradation estimation method

High Mileage NVH (Noise, Vibration and Harshness) performance is one of the major concerns in vehicle design for long term customer satisfaction. One of the main causes of the high mileage NVH degradation is the loss of joint stiffness of body structure due to fatigue, corrosion, loosening, wear and aging. Traditional joint test methods for determining joint stiffness before and after the mileage accumulation require joints to be cut from a vehicle body and are very time consuming and expensive. This paper presents a computational/experimental diagnostic method which can be used to identify the degradation in the stiffness of the joints of a vehicle body structure using frequency response functions measured on a body before and after mileage accumulation. The key idea in this method is to develop and use an equation relating the change in the dynamic response of the zero and high mileage vehicles to the change in the vehicle structure joint stiffness. The method is validated using a body-in-white (B-I-W) CAE model of a production vehicle.