127 Characteristics of javelin made of composite materials

Abstract

In this study, the characteristics of the men's javelin were investigated in terms of its material in order to collect basic data about the required properties of the javelin. Made of various materials (composite materials: 7; steel: 5; duralumin: 8), 20 types of javelins were examined to assess the static characteristics of shape, center of gravity, and moment of inertia, as well as the characteristics of vibration and static bending stiffness. The properties of the composite javelins were clarified, and the effects of javelin material in a javelin throw competition are discussed. Although all the javelins had the same shape, for the composite javelins, wide scatter was observed in the values of the primary resonant frequency, the moment of inertia around the center of gravity, and the compliance at the position of the loop. Therefore, the composite javelins have a pattern of various mass distributions. Further, the composite javelins were stiffer than the steel and duralumin javelins, and exhibited the characteristic that their vibration was easy to damp.