Shinji Yamakawa

A STUDY OF DEVELOPMENT INDICES ESTABLISHED QUANTIFICATION OF ROAD LOAD

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. (A) For the covering abstract see ITRD E121867.

A Study on Estimation of Vertical Road-load Inputs using the Vehicle Frequency Response Function

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 plus or minus 20%, making them sufficiently accurate for practical use. Rices formula was applied as an index for evaluating the prediction accuracy of the power spectral density. A method is also described for using this formula to predict the frequency even in the case of data which are not normal distributions as a whole. (A) For the covering abstract see ITRD E121867.

Classification of Vibration Modes and Optimization of Vibration Characteristics of a Simplified Cylinder Block Model.

An engine cylinder block usually has complex mode shapes. When designing an engine, engineers try to achieve what they think is the best on the basis of their judgement. However they must consider a great variety of modes. In this research, a very simplified 4-cylinder block model has been developed. (1) to classify basic modes both qualitatively and quantitatively, (2) to predict the change in natural frequencies in neighborhood of the target with the optimization method, and (3) to optimize the natural frequency of this model using the techniques of the pseudo-inverse method. It has been found that the similarity between the vectors of natural frequency sensitivity has significant effects on mode-to-mode variations in natural frequency.