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Vehicle service loads need to be measured under actual driving conditions in order to ascertain the strength and durability requirements for customer usage. However, because road-load data are influenced by the vehicle category and specifications of a vehicle, it takes an enormous amount of time and labor to compare them with existing data and analyze the relationship between service loads and vehicle specifications. This paper presents a study concerning the use of the frequency response function, which differs from one vehicle to another, as a means of predicting the response of a particular target vehicle based on the road-load data, which are input by unevenness of roads, measured for a baseline vehicle. The results predicted in bench tests showed a margin of error of around ±20%, making them sufficiently accurate for practical use. Rice's formula was applied as an index for evaluating the prediction accuracy of the power spectral density.

It is essential to attain accurate understanding of vehicle service loads for customer usage and to reflect this understanding into development test conditions established to ensure strength and durability. The Road Load Standardization Subcommittee* of the Japan Society of Automotive Engineers (JSAE) Fatigue and Reliability Committee has therefore employed direct measurement and new analytic methods in an attempt to quantify Japan-wide on road service load data. This quantified data has been used as the basis to standardize road loads for a wide range of vehicle categories. The following were major considerations in the implementation of this research: Employment of a 6 degree of freedom (6DOF) wheel force transducer (increased measurement accuracy) Identification of load from road input vs input from driving operation generated.