碳纤维/环氧树脂复合材料3.0～6.5 km/s超高速撞击成坑特性研究

为研究碳纤维/环氧树脂复合材料在超高速撞击下的成坑特性,利用二级轻气炮开展了直径为1.00～3.05 mm的铝球以3.0～6.5 km/s的速度正撞击尺寸为100 mm×100 mm×20 mm的碳纤维/环氧树脂复合材料靶板的实验,获得了碳纤维/环氧复合材料靶板的成坑形貌特征,并测量了坑深、成坑表面积、表面损伤面积等尺寸。结合文献数据分析了靶板的无量纲成坑深度p/d_p、无量纲坑径系数D_h/d_p、表面损伤面积等效直径D_e等随撞击速度、撞击能量的变化规律。结果表明:碳纤维/环氧树脂复合材料的无量纲成坑深度p/d_p和无量纲坑径系数D_h/d_p均与撞击速度呈2/3次幂关系;表面损伤面积等效直径D_e与弹丸撞击能量E呈幂函数关系;成坑深度大于成坑半径。

Crater characteristics of carbon fiber/epoxy composite under hypervelocity impact in the velocity range from 3.0 km/s to 6.5 km/s

To study the crater’s characteristics of carbon fiber/epoxy composite targets at the impact velocity of 3.0－6.5 km/s, experiments of some composite targets impacted by spherical aluminum projectiles were carried out by applying a two-stage light gas gun in China Aerodynamics Research and Development Center. The targets were one kind of unidirectional braiding laminates made of carbon fiber and epoxy. The density of the targets was 1.5 g/cm3 and the size was 100 mm×100 mm×20 mm. The targets were clamped by two aluminum plates in experiments. One aluminum plate with the thickness of 2.5 mm was set 40 mm behind the targets to test fragments after the targets. The projectile diameter ranged from 1.00 mm to 3.05 mm. The damage feature of each target was obtained. A central crater surrounded with a shallow spalling region was observed in all recovered targets. Different from a semi-spherical crater, the central crater had a proximately quadrate edge, a semi-spherical bottom and a tough and rugged wall. The shallow spalling region was extremely irregular. The parameters of the crater and the shallow spalling region, such as the crater depth, the superficial area of the crater, the superficial area of the spalling region, were measured and analyzed. Moreover, the variations of the dimensionless crater depth p/d_p, the dimensionless equivalent crater diameter D_h/d_p and the equivalent diameter D_e of the spalling region with the impact velocity and energy were analyzed. Results show that the p/d_p depends on the density ratio ρ_p/ρ_t with a power of 1/2, and on the impact velocity v_i with a power of 2/3. The results are in good agreement with NASA’s hypervelocity experiments on reinforced carbon-carbon targets. The relationship of D_h/d_p with ρ_p/ρ_t and v_i is similar to that of p/d_p with ρ_p/ρ_t and v_i. D_e is a power function of impact kinetic energy. The crater-shape coefficient p/D_h is slightly greater than 0.5, which means the crater depth is larger than the crater radius.