Abstract
The automotive industry faces severe challenges in the coming years. Rapidly changing technology has revolutionaries how vehicles are built, operated, and serviced, since automobile manufacturers must make new models and new technologies to lead the fashion. Most structures of automobile are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. It is rarely obtained the accurate load history of specified positions because of the errors such as modeling, measurement, and etc.
This technique identifies constitutive parameters in the analytical model such that it gives the best possible correlation with the measured test data. The dynamic response due to external force of vehicle structure is described in terms of inverse problem involving principal stresses from experimental and analytical response. The force identification is the combination of the analytical and experimental method with analyzed principal stresses by quasistatic finite element nalysis under unit load and with measured principal stress by strain gages under driving load, respectively.
Engineering systems have very large degrees of freedom in their finite element models, and it is not possible to measure the correct responses at all degrees of freedom because of economic and physical restrictions, therefore sparseness of the measurements is inevitable. This measurement sparseness caused by the characteristics of the measuring instrument and/or by the inexperience of the experimenter is an inevitable factor in the damage detection and assessment. Thus, the sparseness and the noise in the measurements should be considered properly in the force identification. In this study, the regularization technique is adopted to alleviate the ill-posedness of the inverse problems.
To demonstrate the usefulness of the proposed method for the force identification, the heavy-duty bus is examined. Experiment for the bus is conducted on a road simulator with Belgian road (proving ground) data and Quasi-static F.E. analysis is performed. The proposed procedure can be extended to the structural modification of any vehicle systems, since it can identify the external load to evaluate the fatigue life and strength of vehicle structures as the force identification method. This practical load determination procedure will improve the designing process for the redesign of potentially failure components or sub-structures without full car experiment.