Investigation Of The Throwing Distance Dependence On The Releasing Parameters Of Javelin

In this paper, firstly the literatures concerning javelin throwing were overviewed in the past years. From previous papers, researches on the javelin included many aspects, -studies on the personal technique and skills, investigation on the characteristics of javelin aerodynamics, qualitative and quantitative analysis on the throwing action using high speed photography and numerical simulation on javelin moving with computer. Secondly, the dynamic equations of moving javelin were derived by rigid body dynamics; and based on the characteristics of rigid body, the javelin initial parameters after releasing were determined, for example, release height, release velocity, release angle, angle relative to free air stream, lean angle between javelin axis and ground, and direction angles relative to inertia coordinate system. Thirdly, the dimensions of Crown brand javelin were measured, and javelin shape data were obtained; some specimen were also made from the Crown brand javelin, and measured the density and Young's modulus of specimen. Lastly, based on the data obtained, the javelin using FEM was modeled by Femb preprocessing software; the properties of materials and elements were set , loads and boundary conditions were added; then the problem with and without air damping force was solved under the given initial parameters.The simulation results showed that : (a) The higher the release velocity of javelin was, the farther the throwing distance was; and the throwingdistance was significantly affected by release velocity. Generally, throwing distance with 32m/s is two meters more than the distance of 26m/s, and becomes significance with increasing the release angle, (b) Under the condition of no air drag and uniform release velocity, the throwing distance increases proportional to release angle. When release angle is 45 degree, the throwing distance is the farthest, and the farthest throwing distance with air drag is not obtained by releasing javelin with 45 degree, and throwing distance is concerned with release velocity. If releasing javelin with higher velocity, the farther throwing distance can be obtained by lower release angle; If lower release velocity, the farther distance can also be obtained with higher release angle, (c) With no air drag and zero attack angle, and under the conditions of uniform release velocity and angle, the throwing distance is increased with release height, about 1 mm/mm. But with air drag , the effect of release height on throwing distance is not significant. In this paper, all simulations were under the conditions of zero attack angle, so the air drag was the smallest without initial attack angle, and the actions of pitching moment was small after releasing, so the effects on throwing distance were not significant with and without air damping force.