Evaluating Penetration Strengths of Rubber Sheets under Transverse Pressure

Abstract

In this paper, penetration strengths of the natural and syntactic rubber sheets with thicknesses of 3.0 and 2.3 mm subjected to transverse pressure were determined when the small impactor having a weight of 24.8 g collided with the sheets by using the measurement system of impact load and sheet deflection based on electromagnetic induction phenomena. The rubber sheet set at the end of the pressure chamber was deformed initially by vacuuming or pressurizing the inside of the chamber before the penetration tests of the sheets. The histories of the impact force and sheet deflection were analyzed from the electromotive force generated in five coils near the deformed sheet when the impactor containing a neodymium magnet collided with the sheets according to Faraday’s law of induction. Every sheet was penetrated when the impactor collided at approximate 60 m/s with the sheet under the initial transverse pressure of 40 or −40 kPa. Determining the absolute deflections from the position before applying the transverse pressure, the impact load–absolute deflection curves of the impact tests under the different transverse pressure conditions were mutually compared to evaluate the penetration strengths of the sheets. As a result, the critical condition for penetrating the rubber sheets was clarified not to be the maximum impact load but the absolute deflections at the maximum impact loads independently of the transverse pressure.