DYNAMIC CHARACTERIZATION OF FREQUENCY RESPONSE OF SHOCK MITIGATION OF A POLYMETHYLENE DIISOCYANATE (PMDI) BASED RIG-ID POLYURETHANE FOAM

Abstract

KOLSKY COMPRESSION BAR EXPERIMENTS WERE CONDUCTED TO CHARACTERI-ZE THE SHOCK MITIGATION RESPONSE OF A POLYMETHYLENE DIISOCYANATE (PMDI) BASED RIGID POLYURETHANE FOAM, ABBREVIATED AS PMDI FOAM IN THIS STUDY. THE KOLSKY BAR EXPERIMENTAL DATA WAS ANALYZED IN THE FREQUENCY DOMAIN WITH RESPECT TO IMPACT ENERGY DISSIPATION AND ACCELERATION ATTENUATION TO PERFORM A SHOCK MITIGATION ASSESSMENT ON THE FOAM MATERIAL. THE PMDI FOAM MATERIAL EXHIBITS EXCELLENT PERFORMANCE IN BOTH ENERGY DISSIPATION AND ACCELERATION ATTENUA-TION, PARTICULARLY FOR THE IMPACT FREQUENCY CONTENT OVER 1.5 KHZ. THIS FREQUENCY (1.5 KHZ) WAS OBSERVED TO BE INDEPENDENT OF SPECIMEN THICKNESS AND IMPACT SPEED, WHICH MAY REPRESENT THE CHARACTERISTIC SHOCK MITIGATION FREQUENCY OF THE PMDI FOAM MATERIAL UNDER INVESTI-GATION. THE SHOCK MITIGATION CHARACTERISTICS OF THE PMDI FOAM MATE-RIAL WERE INSIGNIFICANTLY INFLUENCED BY THE SPECIMEN THICKNESS. HOWEVER, IMPACT SPEED DID HAVE SOME EFFECT.