Identification of locations and force histories of multiple point impacts on composite isogrid-stiffened panels

This paper deals with the identification of locations and force histories of multiple point impacts on composite isogrid-stiffened panels using measured longitudinal strain responses of isogrid. The locations and force histories of multiple point impacts are identified so as to adjust the modal coordinates to the measured modal coordinates which are determined from the longitudinal strains measured on the free edge side of isogrid. We examine first the effect of the number of the measured longitudinal strains on the accuracy of identification for a single point impact on a rectangular composite isogrid-stiffened panel. Moreover, we also examine the identification of location and force history of a single point impact at an oblique impact angle. After these examinations, the identification of the locations and force histories of multiple point impacts on the rectangular composite isogrid-stiffened panel are performed, and the validity of the identification is verified by comparing the identification results with the exact ones.