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The series of work introduced in this paper is originated from a structural failure of the vehicle A/C (Air-Conditioner) pipe, and when many possible factors having been excluded, the main investigating endeavor is focused on RLD acquisition and analysis, which eventually leads to the successful design improvement. During this process, many important signal collectives, such as micro-strains, accelerations, and engine speed are provided by RLD acquisition in some predefined conditions. Subsequently, these signals are analyzed both in time and frequency domain. Furthermore, order analysis by correlation of acceleration and engine speed is also performed to find a definite reason. As a conclusion, the root cause to the crack is not excitation from the road, but mainly from the engine. Based on this conclusion, structure design is improved and is theoretically proved to be effective by the RLD comparison analysis.

The correlation of the component load time history with customer usage is becoming a most challenging task for vehicle durability performance development. Modern vehicle design process needs to obtain accurate component load as early as possible. Therefore, several load prediction methods based on vehicle multi-body dynamics model have been developed, such as fully-analytical method, semi-analytical method, etc. Component load prediction process using semi-analytical method is presented in this paper. An instrumented mule car with four wheel force transducers and several data acquisition channels is driven through the proving ground according to test procedure. The road load data obtained from the spindle is used as input signals for multi-body dynamics model which has been correlated with test. The relevant component loads are then obtained. The results in the vertical direction agree with the test data very well for the whole proving ground test procedure.

Rubber bushing is used in vehicle suspension systems and plays important roles as connection, mounting, or vibration isolation. To study rubber bushings, one method is to acquire parameters of the constitutive models of rubber from tests of material sample, and to obtain stiffness curves by simulation. Generally, the low-cost uni-axial tension or compression test is used for this method. But parameters from these uni-axial tests are not accurate enough and only part of the properties is represented. To get more accurate parameters, other costly tests and special equipments will be needed. Another method is to directly test stiffness of rubber bushing parts in six loading directions. The stiffness can also be approximated by using empirical formulas with dimensions of bushings. This method simplifies the bushing model and is limited. A new approach is proposed in this paper. First, radial and axial stiffness tests of rubber bushing are conducted and stiffness curves are acquired.