Laser irradiation effects on glass fiber composite subjected to tangential gas flow

The irradiation effects of 976 nm continuous wave laser on glass fiber reinforced E-51 resin matrix composite are studied experimentally, with a 0.4 Ma tangential airflow, a 0.4 Ma tangential nitrogen flow and no gas flow on the target surface, respectively. Experimental results show that, the incoming laser beam will be severely affected by the gaseous pyrolysis products while without gas flow on the target surface, and the loading of tangential gas flow will reduce the influence. The failure mode of glass fiber is that it melts and then is blown away by gas flow, when laser irradiation happens in the presence of a gas flow parallel to the specimen surface. The main function of the tangential airflow is to enhance the convection cooling effect for a low laser irradiance, thus the tangential airflow is not conductive to the laser damage of glass fiber composite. When the laser irradiance increases, the main functions of the airflow are to reduce the shielding effect of the gaseous pyrolysis products on the incoming laser beam and to supply oxygen, thus the loading of the tangential airflow is advantageous to the laser damage of glass fiber composite. Under three different gas flow states, the mass loss increases with the increasing incident power density. The utilization ratio of laser beam increases up to a saturation value as the incident power density in the range of 100-600 W/cm2.