一种有效评估推进剂药柱老化的方法

固体火箭发动机用的合成推进剂其物理性能会随使用年限发生很大的变化.因此在估算安全界限及重新评估剩余寿命时,需要对时效的火箭发动机在其寿命跨度的各个不同阶段进行结构完整性分析.而且在分析的时候必须采用现时的推进剂物理参数,以获得可靠的分析结果.在推进剂暴露面处,因时效而引起的物理性能变化更是尤为明显.而用传统方法评估的物理参数不可能真实地反映现时推进剂的物理性能.本文提出一种利用小型实验装置测量推进器药柱表面应力应变响应的技术.在此技术中,采用特殊设计的装置测量出推进剂表面以恒速率受压时的应力响应.然后将所测得的应力应变行为与经人工时效的推进剂拉伸试验测得的物理参数建立起相应的关系.研究表明它们之间存在着很好的对应关系,它能明确给出发动机推进剂的物理性能参数.与传统方法相比,它既安全又经济.

Technique to Assess Aging of Propellant Grain

Physical properties of composite propellants used in solid rocket motors change significantly with age. To predict the margin of safety and to reevaluate the remaining service life, the structural integrity analysis of solid propellant grains of aged rocket motors is performed at various stages of their life span. To have the reliable results from these analyses, it is mandatory to use the current physical properties of the propellant at the time of analysis. Change in physical properties due to aging is more significant at exposed surfaces. Traditional methods of assessing current physical properties may not truly rep resent the properties of the batch. The paper presents a novel technique to measure the stress strain response at the exposed surface of propellant grain using a miniature-testing device. This specially designed device is able to measure the stress response while the propellant surface is compressed at a constant rate. This measured stress strain behavior is then co-related with the physical properties measured by routine tensile tests of the similar type of propellant which is aged artificially. It is observed that there exists an excellent correlation between the measured stress values by the sensor and physical properties measured by uni-axial tensile test. This nondestructive technique provides properties of propellant grains of all the motors in the batch comprehensively. The technique is safe as well as economical as compared to the traditional methods.