鸟撞试验弹托脱壳过程模拟与试验验证

Simulation and Test Verification of Sabot Separation During Bird Impact Test

为避免在航空发动机风扇鸟撞试验中弹托在剥离时发生破损而导致其碎片飞入试验舱,开展了鸟撞试验脱弹过程的冲击动力学研究。采用LS-DYNA动力学仿真软件对鸟撞试验中弹托与脱弹器撞击过程进行了数值仿真分析。考虑到脱弹过程中材料高应变率的影响,应用Johnson-Cook材料模型描述了弹托和脱弹器的本构关系,采用有限元分析获取了弹托的变形、位移、应力、动能等参数的变化过程。采用压缩空气炮进行了鸟弹发射,并将弹托变形的仿真结果与试验结果进行了对比。结果表明:弹托变形的仿真结果与试验结果相差4.4%,证明仿真方法有效;在脱弹过程中弹托前端会张开,产生喇叭口状变形;弹托中后部的应力水平始终保持在80 MPa以下,不会因冲击作用发生破损而导致其碎片飞入舱体。

In order to avoid the debris coming into test chamber caused by sabot separation during bird impact test,the impact dynamics was studied for bird impaction test arresting process. LS-DYNA dynamic simulation software was used to simulate and analyze the impact process between bird sabot and arresting equipment in bird impact test. Considering the influence of material high strain rate in the process of arresting,Johnson-Cook material model was used to describe the constitutive relationship between bird sabot and arresting equipment,and the change process of parameters such as deformation,displacement,stress and kinetic energy of bird sabot was obtained by finite element analysis. The compressed air gun was used to launch the birdshot,and the simulation results of the deformation of the bird sabot were compared with the test results. The results show that the difference between the simulation results and the test results of the deformation of the bird sabot is 4.4%,which proves that the simulation method is effective. In the process of arresting,the front of the sabot will open,resulting in bell mouth deformation. The stress level is always kept below 80 MPa at the middle and rear of the sabot,and its debris will not come into the test chamber due to damage caused by impact.