【作者】 焦雯；

【导师】 黄海明；

【作者基本信息】 北京交通大学 ， 工程力学， 2011， 硕士

【摘要】 激光技术已广泛应用于高技术产业和军事国防中。激光辐照材料的响应与机理,既是激光加工材料的基础,也是激光武器与抗激光加固的核心理论之一；对激光辐照材料热弹性机理急待研究。基于传热学和弹性理论,针对强激光辐照板的热响应与冲击问题,主要研究了单脉冲和多脉冲激光辐照板的非(?)Fourier效应。本文主要工作：(1)根据烧蚀理论与物质对激光的吸收、反射机理,建立了强激光辐照板的物理与数学模型,它涉及到热辐射和烧蚀引起移动边界非线性问题。(2)基于数值传热学,利用Matlab编程对强激光辐照板的热响应进行数值模拟。结果表明：1)导热系数的取值(函数、常数)引起温度变化速率不同；随时间的推移,受热表面的温度趋于一致,而背面温度相差较大；物体内部温度分布趋势大体相同。2)强激光辐照薄板更适于采用非Fourier导热定律,无论采用单脉冲还是多脉冲激光,温度场均表现出明显的延迟性,并随着松弛时间的增大,延迟性加强。(3)基于热响应与薄板小变形假设,利用板的运动微分方程对强激光辐照薄板引起的热冲击进行数值模拟。结果表明：1)单脉冲激光辐照薄板时,非Fourier现象显着,热弯矩在加热初期逐渐增大,随后减小。2)多脉冲激光辐照薄板时,热弯矩会出现负值,随着薄板空间域温差逐渐缩小,热弯矩也逐渐减小。3)无论单脉冲还是多脉冲激光作用,都会出现反鼓包现象,挠度变化趋势由热弯矩的变化决定。更多还原

【Abstract】 Laser has been widely used in high technology industry and military defense. The response and mechanism of laser irradiating materials is not only the foundation of laser processing materials, but also one of the core theories of laser weapons and anti-laser reinforcement. So it is necessary to study on the thermo-elastic response of plate under intense laser radiation.Based on heat transfer and elastic theory, for thermal response and impact of plate under intense laser radiation, we primarily study on non-Fourier effect of single and multiple pulse laser irradiating plate. The main work of this paper is:(1) According to the theory of ablation and the mechanism of absorption and reflection of material, we establish the physical and mathematical model, which involves thermal radiation and ablation nonlinear problems caused by moving boundary.(2) Based on numerical heat transfer, we do the numerical simulation on the thermal response of plate under intense laser radiation. The results are:1) the heat conduction coefficient (function or constant) cause in different temperature change rate; the temperature of heating surface tends to accordance and the temperature difference of the back is relatively large with time increasing; the temperature distribution of interior is approximately the same.2) It is more suitable to utilize non-Fourier thermal conductivity to research on intense laser irradiating thin plate. Whether using single or multiple pulse laser, the temperature fields are shown obvious delay, and the delay turns stronger as slack time is increasing.(3) On the base of thermal response and small deformation hypothesis, we utilize motion equations of plate to do the numerical simulation on the thermal impart of thin plate under intense laser radiation. The results are:1) single pulse laser irradiating thin plate, non-Fourier effect is obvious, and heat bending moment gradually increases earlier then decreases.2) Multiple pulse laser irradiating thin plate, the bending moment will appear negative and gradually decrease, as the temperature difference of thin plate decreases.3) Whether using single or multiple pulse laser, the thin plate appear reverse bulge phenomenon, and the deflection change trend is decided to the change of heat bending moment.更多还原