冲击载荷下单螺栓连接结构力学行为试验与仿真研究

Experimental and Numerical Simulation of Mechanical Behavior of Single Bolt Connection Structure under Impact Load

关键词:  航空发动机  冲击载荷  螺栓连接结构  损伤机理  SHPB试验

Key words:  Aero-engine  Impact load  Bolt connection structure  Damage mechanism  SHPB test

摘要:

基于霍普金森压杆（Split Hopkinson Pressure Bar，SHPB）装置，对发动机结构设计中广泛使用的螺栓连接结构开展了冲击试验，研究了冲击载荷作用下单螺栓结构的承载能力、损伤模式和失效机理，掌握了冲击速度、预紧力、装配间隙的影响规律。在瞬态显式动力学软件ANSYS/LS-DYNA中，对单螺栓连接结构的冲击试验进行了数值仿真分析，其中螺栓结构采用考虑螺纹细节的精细有限元模型，仿真获得的应变波传播规律与试验吻合良好，验证了该模型的有效性。试验与仿真结果表明：单螺栓连接结构冲击过程分为初始加载与滑移、接头双峰强加载、卸载三个阶段；冲击速度越大，冲击力峰值显著增加；增大螺栓装配间隙或适当提高预紧力均可增强螺栓连接结构的抗冲击剪切能力，而过大的预紧力则会使抗冲击剪切能力下降；螺栓的失效模式为剪切压溃失效。

Abstract:

Impact tests were conducted on single bolt connection structure， which are commonly employed in the design of aero-engine using Split Hopkinson Pressure Bar apparatus （SHPB）. The load bearing capacity， damage modes， and failure mechanism of single bolt connection structure under impact load were investigated， and the influences law of impact speed， pre-tightening force and assembly clearance were figured out. Transient explicit software ANSYS/LS-DYNA was employed to conduct numerical simulation on the impact test process of single bolt connection structure， in which the finite element model of bolt structure were established considering the details of the screw thread. The strain wave propagation law obtained by simulation is in good agreement with the experiment， which verifies the validity of the simulation method. It is indicated by tests and simulation that the impact process of a single bolt connection structure is divided into three stages， i.e. initial loading and slippage， double peaks imposed on the joint， and unloading. The peak impact force increases with impact speed. Increasing the bolt assembly gap and properly increasing the pre-tightening force can enhance the impact and shear resistance of the bolt connection structure， while excessive pre-tightening force will reduce the impact and shear resistance.