中国光学, 2013, 6 (3): 332, 网络出版: 2013-07-01
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
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 laser irradiation laser heating tangential airflow thin plate elastic bending burn-through with no-melting effect damage temperature
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。
Abstract
On the basis of elastic bending theory, the bending deflection expression by both quadrate and circinal 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 diameter, plate thickness and the elasticity modulus(expression is U2a4/Eh3), the damage temperature is related 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 result 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.
刘峰, 彭国良, 杜太焦, 郑艳丽, 阎辉. 切向气流对激光加热金属板非熔化穿孔效应的影响[J]. 中国光学, 2013, 6(3): 332. LIU Feng, PENG Guo-liang, DU Tai-jiao, ZHENG Yan-li, YAN Hui. Influence of tangential airflows on burn-through effect with no-melting of metal heated by laser[J]. Chinese Optics, 2013, 6(3): 332.