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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.

A finite element (FE) approach was conducted for suspension durability analysis with the aid of proving ground and rig tests. First, the displacement and acceleration of spindles were recorded during proving ground tests. The proving ground measurements were reproduced by generating the stroke signals of driving actuators of test rig in laboratory. The stroke histories of test rig are collected as durability road load database. These stroke histories were also used as input for an explicit FE code to capture dynamic behavior of vehicle under durability road load conditions. Comparing the results of experimental measurements and FE analyses, displacement and acceleration of FE results agree with those of proving ground tests. The magnitudes of strain histories from FE results also agree with those from experimental measurements without extra correlation effort. With the sufficient accuracy of FE results, fatigue analysis of suspension component can be conducted by CAE analysis.

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.

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.