New diagnostic method for evaluating penetration strength of rubber sheet by measuring electromagnetic induction

This paper presents a new diagnostic method for evaluating the penetration strength of a rubber sheet based on electromagnetic induction phenomena. This method was established on the basis of the experimental results of impact tests of specimens when small impactors collided with rubber sheets. The impactor behavior, impact force, and specimen deflection were analyzed based on the electromotive force generated in a coil near the specimens when the impactors containing a neodymium magnet collided with the specimens because the intensity of the electromotive force is proportional to the impactor velocity and because its variation is solely dependent on the position of the impactor. The validity of the analyzed impact force and specimen deflection was confirmed by considering the impactor behavior, which was observed using a high-speed camera, and the external work of the impactors evaluated from the analyzed results. The penetration strength of the rubber sheet was determined from the impact-force history and the impact force-specimen deformation curve based on the analyzed impactor behavior during the collision.