激光活塞热负荷模拟实验需将高斯光束调制成按特定光强分布的多个同心光环,为此提出了基于有限元(FE)分析的激光热负荷光强分布反求设计思想。应用最初设计的整形器对有限元模型进行校核,在合理的范围内调整边界条件参数和活塞材料热物性参数,使模拟结果与实验结果吻合;对于校核后的有限元模型,通过调整光强分布和加载条件以接近目标温度场,从而获得整形器优化设计方案。基于上述方法可实现由目标温度场反求设计出光场分布。研究表明,采用数值模拟方法进行研究,可大幅度缩短整形器设计周期、降低设计费用,并起到虚拟实验的作用,从而提高了热负荷实验的可控性和可预见性。

To accomplish laser-induced thermal loading simulation tests for pistons, the Gaussian beam was modulated into multi-circular beam with specific intensity distribution. A reverse method was proposed to design the intensity distribution for the laser-induced thermal loading based on finite element (FE) analysis. Firstly, the FE model is improved by alternating parameters of boundary conditions and thermal-physical properties of piston material in a reasonable range, therefore it can simulate the experimental results of the originally designed shaping lens. Secondly, with the validated FE model, the target temperature field is achieved by alternating the intensity field and loading conditions, and the optimal design for the beam shaping lens is subsequently obtained. This reverse design method bridges temperature field and intensity field. The results show that numerical simulation can reduce design cycle and design expense efficiently. Meanwhile, this process can be taken as a kind of virtual experiment which makes the thermal loading test more controllable and predictable.