Experiment And Simulation Study Of Sub-impact In Beam Struck By Sphere

The research of impact between the flexible structure has been one of the classic dynamics problems, which exists in nature and engineering field. Sub-impact is the characteristic phenomenon of flexible structure impact, and related research is being carried out gradually. In this paper, the experiment model of beam struck by sphere was took as research object, and combining the local impact contact theory, the spring oscillator model and the finite element numerical simulation method, the research of the sub-impact behavior was started. The main research contents are as follows.(1) The impact experiment scheme of beam struck by sphere was established, and the corresponding sub-impact detection system was set up. Experiment content includes four kinds impact combination of test beam struck by steel sphere, each kind of combination for different velocities and different positions, multiple sets of experiments were carried out.(2) In the process of experiment, the test beam displacement response of the struck zone, the stress strain response of the test points on the test beam, as well as the impact-contact time response were obtained accurately by the sub-impact detection system. Integrating the steel ball trajectory curve, the impact area of test beam trajectory curve and the impact contact time curve, the generative process of sub-impact was shown intuitively.(3) Based on the local impact contact theory and the spring oscillator model, under the condition of elastic and elastic-plastic contact theory, the formulas of the impact contact time were deduced, and were compared with the experiment results.(4) According to experimental results, the relationship between the coefficient of restitution and the impact velocity was studied systematically, and the influence of sub-impact phenomenon to the coefficient of restitution was explored.(5) With the three-dimensional dynamics analysis software LS-DYNA, the finite element model of test beam struck by steel sphere was established. In the process of simulation, related dynamic responses were calculated, and were compared with the experiment results.(6) Through theoretical analysis and simulation calculation, the mass ratio, the impact velocity, the acceleration of gravity and other factors that affect the behavior of sub-impact was studied, and the cause of the sub-impact was explored.