基于概率统计的复合材料壳体的可靠性分析

Reliability analysis of filament-wound composite case based on probability and statistics

为了减轻纤维缠绕固体火箭发动机的消极质量,同时保证其结构的可靠性,以概率统计理论为基础,并结合对某复合材料壳体的大量的内压爆破试验和发动机试车结果进行统计、梳理、归一化处理的结果,对某复合材料壳体进行了可靠性设计分析,获得了基于当前发动机复合材料壳体设计、制造水平的概率安全系数和概率安全裕度。分析结果表明,在保证壳体结构可靠的基础上,概率安全系数相对于传统安全系数更低。当可靠性概率P_(R)在0.999~0.999 999 99范围内时,概率安全系数为f_(1)=1.126 1~1.232 9。依据概率安全系数设计的壳体,其概率安全裕度较实测平均安全裕度降低了38%以上。因此,结合实际制造和使用情况,壳体设计可适当地降低安全系数来减轻壳体质量,以此能够有效地降低发动机的消极质量。

In order to reduce the negative mass of filament-wound solid rocket motor(SRM) and ensure the structural reliability, the reliability design and analysis of a filament-wound composite case were carried out based on the probability and statistics method, by considering a large number of collected and normalized experimental results of bursting pressure and ground test of a certain composite casing.The reliability safety factor and its margin based on the current design and manufacturing level of SRM composite case were obtained.The results show that on the basis of ensuring the reliability of the composite case, the reliability safety factor is lower than the traditional safety factor.When the reliability probability P_(R)is in the range of 0.999~0.999 999 99,the reliability safety factor is f_(1)=1.126 1~1.232 9.The safety margin of the composite case designed according to the reliability safety factor is more than 38% lower than the average values measured.Therefore, combining with the actual manufacturing and application, the negative mass of the SRM could be effectively reduced by reducing the safety factor and the weight of the composite case appropriately in the design process.