Moderately high speed impact of two identical spheres
Moderately high speed impact of two identical spheres
复制标题
DOI：
10.1016/j.ijimpeng.2010.09.005
复制
发表时间：
2011-02-01
影响因子：
5.1
通讯作者：
Kawamura, Shozo
中科院分区：
文献类型：
--
作者：
Minamoto, Hirofumi;Kawamura, Shozo
本文研究了中等高速范围内两个相同球体之间的碰撞问题。球体碰撞是机械动力学中的基本问题之一。冲击的严重程度一般用恢复系数来表示。然而，材料属性对恢复系数的影响尚未得到澄清。作者之前研究了两个相同球体在低速范围内的直接中心碰撞，并发现即使在低速碰撞中，材料性能的应变率敏感性也不能忽视。因此，本文研究了两个相同的球体在较高速度范围内的直接中心碰撞。利用气枪装置在冲击速度10 m/s ~ 20 m/s范围内进行了冲击实验。据证实，恢复系数和接触时间的表达式来自低速冲击仍然有效，在适度的高速范围内。然后采用有限元方法进行了数值模拟，其中考虑了材料性能和应变率效应。通过试验和有限元分析得到了球的恢复系数、接触时间、球的压缩量和接触圆直径。进行了比较，它们匹配良好。最大接触力时的接触压力分布进行了研究。球心处的接触压力随冲击速度变化不大，而接触边缘处的接触压力随冲击速度的增加而增大。提出了预测恢复系数的理论表达式。Thornton对本研究的实验结果进行了检验。为了提供准确的预测，有必要根据材料特性估计接触压力。最后，迈耶分析应用到本研究的情况下，它被发现迈耶定律在两个相同的球体之间的中等高速碰撞。(C)2010爱思唯尔有限公司版权所有。
This paper deals with impacts between two identical spheres in moderately high speed range. Impact of spheres is one of basic problems in mechanical dynamics. Severity of impact is generally characterized by the coefficient of restitution. However, influence of material property on the coefficient of restitution has not been clarified yet. The authors previously investigated direct central impacts of two identical spheres in low speed range and revealed that strain rate sensitivity of material properties could not be ignored even in the low speed impacts. Therefore, this paper investigates the direct central impact of two identical spheres in higher speed range. The impact experiments were performed in range of impact speed 10 m/s-20 m/s by using air-gun setup. It was confirmed that the expressions for the coefficient of restitution and the contact time derived from the low speed impact remained effective in the moderately high speed range. Then numerical simulations by using Finite Element Method (F.E.M) have been carried out, in which the material properties and the strain rate effect were taken into account. The coefficient of restitution, contact time, sphere's compression and contact circle diameter obtained by experiments and F.E.M. were compared and they matched well. Contact pressure distributions at maximum contact force were investigated. The contact pressure at sphere center varied little with impact speed but the contact pressure increased with impact speed near contact edge. Theoretical expression for prediction of the coefficient of restitution proposed by C. Thornton was examined to the experimental results of this study. To provide an accurate prediction, it is necessary to estimate the contact pressure depending on material properties. Finally, the Meyer analysis was applied to the case of this study and it was found that the Meyer's law holds in the moderately high speed impact between two identical spheres. (C) 2010 Elsevier Ltd. All rights reserved.