【作者】 李东；

【导师】 周长省；

【作者基本信息】 南京理工大学 ， 兵器发射理论与技术， 2008， 博士

【摘要】 固体火箭发动机作为战术导弹或野战火箭的动力装置和关键部件,其安全性非常重要。从己知的导弹及火箭故障来看,固体火箭发动机失效是导致灾难性故障的最主要原因,而失效主要是由于药柱结构完整性的破坏。因此,在固体火箭发动机设计阶段,需要大力开展发动机的结构完整性分析,其中药柱的结构完整性是关键技术之一。在药柱结构完整性分析中,形变和断裂特性研究一直是十分活跃的研究课题。本文通过建立由三维非线性粘弹性本构关系描述的固体推进剂药柱有限元模型,利用数值方法分析药柱表面裂纹的动态场特性,对裂纹尖端应力应变场的分布及其动态场对加载率的响应特征进行了研究。主要研究内容为:1.通过研究广义粘弹性本构方程在固体推进剂材料中的适应性,利用非线性有限元分析中的通用求解方法对单轴和多轴粘弹性本构关系进行了分析,运用递归迭代算法编制了用户材料子程序。2.建立由三维非线性粘弹性本构关系描述的有限元模型,通过数值计算结果与实验结果对比的方式对方程的有效性进行验证。3.利用三种加载方式对带裂纹的典型药柱结构的裂纹尖端场进行了数值计算。通过将三维非线性粘弹性数值方程转化成动态条件下本构模型,编制VUMAT(动态分析用户材料子程序),分别对施加三种不同加载率的不同长度裂纹进行有限元计算,考虑裂纹对动态载荷的响应,分析了应力应变场的变化规律。4.利用典型药柱结构的裂纹尖端场数值计算结果分析了加载率对裂尖前方张开应力场的影响,并预测了动态加载条件下的断裂韧性。通过本文的研究,得到了固体推进剂表面裂纹在动态加载条件下的力学响应特性、场变化规律和裂纹起裂特征。本文的研究工作将对固体火箭发动机结构完整性分析,特别是对固体推进剂药柱结构完整性分析奠定坚实的基更多还原

【Abstract】 The safety of a solid rocket motor, which serves as the propulsion system and the key component of a tactical missile or a field rocket, was extraordinary important. Known from the View of solid missile fault, solid rocket engine failure led to the catastrophic failure was the main reason, and the failure was mainly due to the structural integrity of the grain damage. As a result, study on analysis of structural integrity of the engine should be energetically developped on solid rocket design stage, the structural integrity of grain was one of the key technologies. In the analysis of the structural integrity of grain, study on deformation and fracture characteristics was always a very active research subject.In this paper, the solid propellant grain finite element model charactered by three-dimensional nonlinear viscoelastic constitutive relationship was established, the dynamic field characteristics of solid propellant surface crack was simulated from numerical methods, the distribution of crack tip stress-strain field and the response characteristics of dynamic field on loading rate were studied. The main contents were as follows:1. By studying applicability of generalized viscoelastic constitutive relation in solid propellant material, uniaxial and multi-axial viscoelastic constitutive relation were analyzed by using currency resolving method in nonlinear finite element analysis, and UMAT was programmed by recursion-iterative arithmetic.2. Finite element model charactered by three-dimensional viscoelastic constitutive relation was established and analyzed ,the validity of three-dimensional viscoelastic constitutive relation was validated by comparing numerical result with test result.3. Crack-tip fields of representative grains structure contained precrack was conputed by numerical mothed in three loaded type.VUMAT was programmed by changing the three-dimensional viscoelastic constitutive numerical equation into dynamic constitutive numerical model, the different length crack applied three type load was computed by finite element method, the reponse of crack in dynamic applied load was calculated and the law of crack-tip fields was analyzed.4.The effect loading rate on open stress fields in crack-tip ahead was analyzed by numerical competed result of the crack-tip fields in representative grains structure, and fracture roughness in dynamic applied load was predicted.Through research of this paper, the response to the mechanical properties, the law of Field changes and the start features of crack of solid propellant surface crack with dynamic load conditions were obtained. laid a solid foundation to the analysis of structural integrity of rocket engine, especially to the structural integrity of grain.更多还原