预应力加载下LY12-CZ激光烧蚀特性的实验与模拟研究
Laser Ablation Characteristics of Prestressed LY12-CZ:An Experimental and Simulation Study
堵志钦 1张宇 2师先哲 1惠煜中 1沈将华3
作者信息
- 1. 西北工业大学航空学院,西安,710072
- 2. 西北工业大学航空学院,西安,710072;中国飞机强度研究所结构冲击动力学航空科技重点实验室,西安,710065
- 3. 西北工业大学航空学院,西安,710072;陕西省冲击动力学及工程应用重点实验室,西安,710072
- 折叠
摘要
飞行器是激光武器的主要打击目标,对常用航空材料激光辐照响应的研究具有重要价值.本文通过实验和有限元模拟的手段,研究了预应力加载下,1080 nm连续激光烧蚀LY12-CZ铝合金的失效机理.实验结果表明,激光烧蚀沿光斑径向存在三种组织,分别为近光斑的枝晶组织、中部的等轴晶组织及远离光斑的原始组织;其中,枝晶、等轴晶组织中存在严重的Cu元素偏析,且等轴晶组织还存在较高的内应力.有限元模拟的结果表明,温度场对所施加的预应力并不敏感;烧穿孔洞形成的一个原因是局部因热软化和高水平热应力造成的屈服;预应力不能显著改变激光的烧蚀特性.
Abstract
Considering that aircrafts are typical targets for laser weapons,and aircraft materials are used under complex mechanical conditions,the response of these materials under laser and prestressing holds significant value in the aeronautic industry.However,current research on material response under combined laser and prestressing mainly focuses on mechanical failure affected by laser irradiation,with limited in-depth understanding of laser ablation characteristics and microscopic mechanisms.In this study,we investigate the laser ablation characteristics of LY12-CZ alloy by means of experiment and simulation.We analyze the ablative morphology under prestressing and characterize microstructure and element distri-bution in the remaining samples.The Vickers hardness test along the radial direction of the heat source is carried out.In addition,a finite element simulation of laser ablation under prestressing is performed based on the fully coupled thermal-stress analysis method.The experimental findings reveal three distinct struc-tures along the radial direction of the spot:the dendrite structure near the spot,the equiaxed grain struc-ture in the middle,and the original structure far away from the spot.Both the dendrite and equiaxed grain structures exhibit severe segregation of Cu element,while the equiaxed grain structure also experiences high internal stress.The hardness in the dendrite structure is close to 80 HV and increases sharply to a-round 120 HV in the equiaxed grain structure.In the transition zone from the equiaxed grain structure to the original structure,the hardness decreases first and then increases.Prestressing does not have an obvi-ous effect on the distribution of microstructure,element segregation,and hardness after laser ablation.Simulation results indicate that the temperature field is not significantly influenced by the applied pre-stress.The thermal stress caused by the rise in irradiation temperature is much higher than the applied prestress,leading to the formation of burn-through cavities and local thermal softening of the material.It is found that prestressing does not significantly alter the laser ablation characteristics of LY12-CZ alloy.
关键词
激光烧蚀/预应力/微观组织/有限元模拟Key words
laser ablation/prestress/microstructure/finite element simulation引用本文复制引用
出版年
2024
NETL
NSTL
万方数据