切向气流对激光加热金属板非熔化穿孔效应的影响  

Influence of tangential airflows on burn-through effect with no-melting of metal heated by laser

作　　者：刘峰[1,2] 彭国良[1] 杜太焦[1,2] 郑艳丽[1] 阎辉[1] 

机构地区：[1]西北核技术研究所第五研究室,陕西西安710024 [2]激光与物质相互作用国家重点实验室,陕西西安710024

出　　处：《中国光学》2013年第3期332-342,共11页Chinese Optics

基　　金：激光与物质相互作用国家重点实验室基金资助项目(No.SKLLIM1102)

摘　　要：针对切向气流加载导致激光加热金属板在熔化前的穿孔效应,利用金属薄板的弹性弯曲理论,推导出了两种典型光束(方形和圆形)照射下的弯曲挠度表达式,利用Mises理论给出了非熔化穿孔的破坏判据。研究结果表明:激光加热下材料强度降低是出现非熔化穿孔破坏的主要机理;薄板在光斑区的最大变形与气流速度、光斑直径、板厚与弹性模量(U2a4/Eh3)相关,穿孔破坏温度与气流速度、光斑直径及板厚(Ua/h)2相关;与方形光斑辐照相比,圆形光斑辐照的破坏阈值稍高一些。数值计算结果表明:0.8 Ma切向气流作用下,铝合金壳体的激光破坏能量阈值大大降低(可达40%～50%),典型不锈钢壳体的破坏阈值降低相对较小(20%左右),气流作用导致金属板破坏阈值的下降是需特别关注的问题。On the basis of elastic bending theory, the bending deflection expression by both quadrate and cir- cinal facula irradiations is deduced for burn-through effect with no-melting of metal heated by a laser caused by tangential airflows. A rupture criterion for burn-through with no-melting is given out by the Mises theory. The study indicates that the material softened by laser heating is the primary mechanism for burn-through effect with no-melting. The maximal deflection of thin plate in the spot area is related to the airflow speed, spot di- ameter, plate thickness and the elasticity modulus（ expression is U2a4/Eh3）, the damage temperature is relat- ed to the airflow speed, spot diameter and the plate thickness （expression is （Ua/h）2）, and the damage threshold under the circinal facula irradiated is higher than that under the quadrate facula. The numerical re- suh indicates that for aluminum alloy shell, the damage threshold of laser energy can decrease much up to 40% - 50% under 0. 8 Ma tangential airflows, but it can decrease less （ about 20% ） for a stainless steel shell. The damage threshold decrease under airflows needs more attention.

关 键 词：激光辐照 激光加热 切向气流 薄板弹性弯曲 非熔化穿孔效应 破坏温度 

分 类 号：TN249[电子电信—物理电子学] TG665[金属学及工艺—金属切削加工及机床]