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The purpose of this paper is to apply the concept of the frequency spectrum as derived from a Single Degree of Freedom (SDOF) system, establish the accelerated vibration specification, and investigate the specification under customer usage with reliability analysis. The main technique is to convert a time domain signal, which is derived from a Proving Ground or customer usage, to the frequency domain. An automotive headlamp was used in our research. The input signal from the Proving Ground was converted into an eight-hour bench test that is equivalent to a five-year/100,000 km field usage through the theory of Fatigue Damage Equivalence. The fatigue parameters of the materials were then estimated from various vibration conditions with the MIL-STD-810F standard. The benefit of this approach is that we could quickly obtain the material parameters of a complex structure made of composite plastics.

Ride quality analysis involves the study of three topics: ride excitation sources, system dynamics of a vehicle, human perception and tolerance of vibration. In this study, we establish an integration analysis procedure including the system dynamics analysis and the ride quality evaluation. The dynamic responseof a passenger car was simulated by a multi-body model with ADAMS software. The calculated acceleration responses of seats coincide with the field measured ones. The effect of damping ratio (C), stiffness coefficient (K), vehicle speed and seating location on the acceleration response are also investigated. The ride quality analysis was conducted following the ISO 2631 standard. A LabVIEW computer code was developed to provide fast and convenient assessment of the comfort. A 3-axis translational accelerometer was installed on the seat.

The durability and riding comfort performance of a new type scooter were investigated by bench test. The long-term road load data of Taiwan market were measured with accelerometers and strain gauges by the on-line rainflow cycle counting method. The equivalent test track corresponding to 50,000 km in Taiwan market was established with ARTC's proving ground (Automotive Research and Testing Center in Taiwan) by correlation analysis technique. Then we performed the full vehicle bench durability test with load histories obtained by the road simulation technique. After a series of testing, analysis, and modification, the test vehicle already got a satisfactory result for the durability performance. Riding comfort analysis was performed following the ISO 2631 standard with accelerometers near the seat and foot in the bench testing. In order to get an optimum combination of suspension system for this new type scooter, many sets of front and rear suspensions were evaluated.

To investigate fatigue failure of motorcycle handlebars, fatigue analysis and durability experiments are conducted in this study. The finite element software, MSC.Nastran, was used to obtain the stress distribution of a handlebar subject to loadings in various directions. The results of FEM analysis were compared with those of static test to obtain optimum applied loading direction in the durability test. The strain history of the handlebar was measured when a motorcycle traveled on the Belgium (Pave) Road. The applied loading history in the durability test was obtained with remote parameter control technique. Three methods including “traditional S-N approach”, “BS 5400 approach” and “BS 5400 with Gurney thickness modification approach” were used to analyze the fatigue life of the handlebars. Rainflow cycle counting method and Miner’s damage accumulation rule were applied.