【作者】 孙岳；

【导师】 黄海明； 高锁文；

【作者基本信息】 北京交通大学 ， 工程力学， 2008， 硕士

【摘要】 激光已广泛应用于国防,以及材料的加工和修复,需要深入研究靶材与激光相互作用的机制;未来战争中激光武器的发展和应用是必然趋势,因此对激光破坏机理进行一些基础性研究是必要的。随着航空航天领域中复合材料的广泛应用,激光辐照复合材料机理,既是复合材料激光加工的基础,也是抗激光武器研制的基础理论之一。本文基于通用傅里叶导热定律,研究靶材在强激光辐照下其内部温度场和热应力场的响应问题,考虑非傅里叶效应推导出多脉冲热流以及矩形恒定温度波作用下半无限大物体温度场和热应力场通用傅里叶定律的解析表达式,并实际计算出考虑非傅里叶效应时半无限大物体内部温度场和热应力场的分布规律。应用有限元方法数值模拟出半无限大物体在相应热荷载作用下的温度场和热应力场。在实验分析的基础上,数值模拟出碳纤维树脂基复合材料受到激光引起的热荷载和冲击荷载耦合作用下的响应,进一步对激光烧蚀压力和反冲塞效应进行了理论探讨,并运用数值实验的方法得到了烧蚀压力的计算公式。主要取得的成果如下:(1)多脉冲热流作用下,经典傅里叶理论与通用傅里叶理论所计算出的温度波波前振幅均为零,且波动的热流扰动导致物体内各点温度随时间的变化亦具有明显的波动性。但考虑松弛时间的通用傅里叶理论解由于物体内各处温度场的重新建立在时间上滞后于热扰动的改变,进而存在温度不变区域,经典傅里叶解则没有。(2)矩形恒定温度波作用下,通用傅里叶理论解在深度方向上的温度分布曲线存在间断点;而经典傅里叶定律认为热波速度为无限大,得到连续的温度分布曲线而无间断点。(3)通过比较发现傅里叶理论计算结果无明显的热冲击现象,而基于通用傅里叶理论所得到的热扰动应力波波前十分陡峭,具有明显的热冲击性。(4)应用有限元方法数值模拟出的半无限大物体温度场和热应力场,与本文推出的公式中当松弛时间取为零时的计算结果吻合较好。(5)激光辐照碳纤维树脂复合材料时,靶材由于烧蚀压力和激光诱导反冲塞效应的作用,经历短暂膨胀—急剧收缩—缓慢恢复原形三个阶段。更多还原

【Abstract】 Laser has widely used in national defence and the material processing and repair. We should study the mechanism of interaction between the laser and target material. In the future, laser weapon’s development and application will be the inevitable trends, therefore, some basic researches to the laser failure mechanism is necessary. Along with the widespread application of complex material in the aerospace field, the laser irradiation mechanism is not only the complex material laser processing foundation, is also one of the basic theories of anti-laser weapon development.This paper based on the generic Fourier law, studies the target material response of temperature field and the thermal load field under the high energy laser irradiation. Considered the non-Fourier effect, the analytic expressions of the structure temperature field and the thermal load field under the multi-pulse heat flow and the rectangular constant temperature wave were deduced. What’s more, the actual distributed situation of temperature field and thermal load field was computed when the non-Fourier effect was considered. In analyzes to the corresponding experiment, the destruction process and mechanism of carbon fiber resin complex material was numerical simulated, which received the laser’s hot and impulsive load. In addition, the theory discussion of the laser ablation pressure and the reverse-plugging effect were carried on, and the ablation pressure formula was also obtained by numerical experiment.(1) In the pulsed heat flow boundary condition, the oscillation amplitude of temperature wave front is zero, which is calculated by both the classical Fourier theory and the generic Fourier law. And the undulatory heat flow causes the undulatory temperature field along with the time grow. However, the generic Fourier solution has a temperature invariable region, which classical Fourier solution does not exist.(2) In the rectangular constant temperature wave boundary condition, generic Fourier temperature profile exist the discontinuity point in the depth direction, which the classical Fourier solution doesn’t.(3) By the comparison, we find that the Fourier solutions don’t have obvious thermal shock phenomenon. But the generic Fourier solutions obtain a very steep wave front of the thermal agitation stress wave, and they have the obvious thermal shock.(4) The temperature and thermal load field simulated by the finite element method is tallied well with the computed result when the relaxed time takes for the zero. (5) When the laser eradiates carbon fiber resin complex material, because of the ablation pressure and the reverse-plugging effect, there are three stages: short inflation -rapid shrinkage -slow reversion.更多还原