弹塑性点接触冲锤钻杆重复碰撞的建模

发布时间：2018-01-08 20:17

本文关键词：弹塑性点接触冲锤钻杆重复碰撞的建模　出处：《中国地质大学(北京)》2016年硕士论文　论文类型：学位论文

【摘要】：冲击碰撞现象在机械动力学中非常普遍。两个冲击体在冲击碰撞过程中,很有可能在接触的区域产生过高的应力,从而导致产生塑性变形。在机械系统发生连续碰撞时,前一次冲击产生的塑性变形和残余应力会对接下来的冲击碰撞产生影响,所以冲击的状态会随着冲击次数的增加而不同。本文以冲锤钻柱冲击碰撞模型为研究对象,利用ANSYS/LS-DYNA有限元程序对其多次冲击碰撞过程进行数值仿真模拟,具体研究内容如下:一、点接触冲锤钻杆在首次碰撞时,当屈曲区超过接触区时,Hertz接触应力在起始段理论值低于仿真值,这是由于塑形变形大引起点接触刚度增大造成的。当屈曲区与接触区一致时,起始端满足Hertz接触。二、点接触冲锤钻杆在相同冲击速度冲击下,在屈曲区超过接触区的接触状态进行多次冲击碰撞的数值仿真模拟接触力在增加,这是由于随着冲击次数的增加,变形量越来越少,释放的应力就越少。同时随着冲击次数的增加,接触时间是减少的。同样随着冲击次数的增加,加工硬化的产生,残余变形量越来越少,接触力和变形越来越趋于线性刚度,点接触冲锤钻杆在重复碰撞过程中由点接触慢慢变成面(曲面)接触。三、对点接触冲锤钻杆冲击碰撞过程中屈曲区基本与接触区一致的接触状态进行多次冲击碰撞的数值仿真模拟,可以看出其变形量是小的,随着冲击次数的增加,塑性变形量也随着冲击次数的增加而减少,但是接触力和位移仍然存在着Hertz接触指数特征。通过以上研究,利用ANSYS/LS-DYNA有限元程序能够对点冲锤重复冲击碰撞的过程进行数值模拟,可以发现冲锤在重复碰撞之后会由点接触变成面(曲面)接触,可以看出塑性变形对其冲击碰撞过程的影响。这在实际工程中是具有一定价值的。
[Abstract]:The phenomenon of impact collision is very common in mechanical dynamics. In the process of impact impact, it is very possible for two shock bodies to produce excessive stress in the contact area. When the mechanical system collides continuously, the plastic deformation and residual stress produced by the previous impact will affect the subsequent impact impact. Therefore, the state of impact will be different with the increase of impact times. In this paper, the impact impact model of impact hammer drill column is taken as the research object. ANSYS/LS-DYNA finite element program is used to simulate the multiple impact impact process. The main contents are as follows: 1. Point contact impact hammer drill pipe in the first impact. When the buckling zone exceeds the contact zone, the theoretical value of Hertz contact stress in the initial section is lower than the simulation value, which is caused by the increase of the point contact stiffness due to the large plastic deformation, when the buckling zone is consistent with the contact zone. The initial end meets Hertz contact. Secondly, the contact force of point contact hammer drill pipe under the same impact velocity and contact state beyond the contact zone in the buckling region is increased by numerical simulation. This is because with the increase of the number of impact, the less the deformation, the less the stress released. At the same time, with the increase of the number of impact, the contact time is reduced, and the same with the increase of the number of shocks. With the production of work hardening, the amount of residual deformation becomes less and less, the contact force and deformation tend to linear stiffness, the point contact hammer drill pipe slowly changes from point contact to surface (surface) contact during repeated impact. The numerical simulation of the contact state of the buckling zone consistent with the contact zone during the impact impact of point contact hammer drill pipe shows that the deformation is small and the deformation is small with the increase of the impact times. The amount of plastic deformation also decreases with the increase of impact times, but the contact force and displacement still have the characteristics of Hertz contact exponent. The ANSYS/LS-DYNA finite element program can be used to simulate the repeated impact process of point hammer, and it can be found that the impact hammer will change from point contact to surface contact after repeated impact. The influence of plastic deformation on its impact and impact process can be seen, which is of certain value in practical engineering.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH113

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