Influence Of Human Body-javelin System To Javelin Flight Initial Condition And Computer Simulation Of Javeling Flight

In the paper, influence of human body-javelin system to javelin flight initial condition was studied, and javelin flight with air damping force was simulated by computer. First, javelin throwing was introduced from its origin, technical and mechanical principle, and the literatures concerning javelin throwing were overviewed in the past years. Looking over domestic and foreign scholars' research and analysis to javelin throwing technique for several dozens years, it was known that the former research mainly concentrated on some partial aspect research, and also lacked the systematic characteristic to the technical analysis, thus it waited for the further research. Secondly, the research object, research scope, research technique of multi-rigid body system dynamics theory as well as the related aerodynamic theory were inducted. Thirdly, based on multi-rigid body system dynamics theory, human body-javelin system mechanics model which was composed by five rigid bodies was established, and the system dynamic equations were inferred by using dynamical universal theorem, then it was obtained that the relation of the moments of force in rigid body and each rigid body relative angle, accordingly influence of human body-javelin system to javelin flight initial condition was indirectly described. Finally, using the javelin's geometry size data in the paper [22], javelin flight was simulated with fluid-solid coupling by computer. The airbag finite element model was established on the javelin finite element model foundation, simultaneously the properties of material and element were set, and the gravitational field and the function of air to javelin were added, the action of wind to javelin were loaded as well as initial condition of javelin flight (initial velocity, release angle, initial angle of attack and initial angle of pitch speed) is changed. And it is solved by LS-DYNA solver, then was carried on the data processing by the LSTC/LSPOST processor.The simulation result indicated that, (1) in the paper, in the condition of research scope and in other invariable initial condition, the initial velocity of javelin and the flight distance basically assumes the linear relation; (2) In other invariable initial condition, when the release angle of the javelin is in the scope of 0°～42°, with the release angle's increasing, the flight distance unceasingly increases basically, but when the release angle of the javelin is greater 42°, its increasing scope has the tendency which reduces. By the simulation result, the best release angle of the javelin is approximately 42°; (3) When other initial condition is certain, and the initial angle of pitch speed is below 0, the flight distance of the javelin is farther than it is when it is up 0. The best initial angle of pitch speed is about -0.26rad/s～-0.17rad/s; (4) In other certain initial condition, the change of the initial angle of attack is not certainly remarkable to the influence of the flight distance. Furthermore, in these combination of the initial angle of attack and the different initial angle of pitch speed, when the combination is"B₀=42°, A₀=-8°, W_Z0=-0.09rad/s", the flight distance is farthest, and achieves 91.794m. When the initial condition deviates this combination, the flight distance reduces; (5) The wind is remarkable to the influence of the flight distance. For the dead wind, in other certain initial condition, with the wind speed's increasing, the flight distance of the javelin presents the tendency of reduction. But, under the same speed of dead wind, when the release angle in the initial condition is continue to increase, the flight distance unceasingly increases; when the release angle adds up to 42°, its flight distance, however, little reduces.