碳纤维增强环氧树脂复合材料在切向气流和激光作用下的损伤

Damage of carbon fiber reinforced resin matrix composite subjected to laser and tangential gas flow loading

实验研究了靶板表面有0.4Mach(1Mach=340m/s)切向空气气流、0.4Mach切向氮气气流和无气流时,976nm连续激光对碳纤维增强E-51环氧树脂复合材料的辐照效应,得到了该材料在不同功率密度下的烧蚀规律。实验结果表明:当样品发生剧烈热分解时,随热分解气体流出边界的固体颗粒对入射激光有屏蔽作用;切向气流一方面可以减弱这种屏蔽作用,有利于辐照区的烧蚀,另一方面对样品有冷却作用,不利于烧蚀;相比于氮气流,空气流有助于产物的燃烧,对下游附近区域产生明显的加热作用;切向空气气流的加载会明显提高扩散到样品表面的氧气浓度,导致碳纤维发生氧化烧蚀;三种气流状态下,当入射激光功率密度在100～800W/cm2范围内,随着功率密度的增大,激光能量的利用效率逐渐降低。

The irradiation effects of 976 nm continuous wave laser on carbon fiber reinforced E - 51 resin matrix composite were studied experimentally, with a 0.4 Mach（1 Mach= 340 m/s） tangential airflow, a 0.4 Mach tangential nitrogen flow and no gas flow on the target surface, respectively. The ablation laws of the materials were obtained for various laser power densities. Experimental results show that, when the pyrolysis happens severely, the solid particles flowing out of the interface with the pyrolysis gas, will shield the incident laser. The tangential gas flow, on one hand, can weaken the shield effect of the solid particles outflow the interface, which is helpful to the ablation in the irradiated area. On the other hand, the tangential gas flow can cool the target, which is adverse to the ablation. Comparing with the nitrogen gas flow, airflow is of advantage to the combustion of the production, which can heat the downstream area obviously. The loading of the tangential airflow will promote the diffusion of the oxygen to the target surface, which results in the oxidative ablation of the carbon fiber at a low temperature. Under three different gas flow statuses, the utilization ratio of the laser beam decreases with the increasing incident power density, for the power density in the range of 100-800 W/cm2.