纤维缠绕复合材料结构可靠性评估方法及其应用

Reliability Evaluation Method and Its Application for Fiber Wound Composite Structures

关键词:  结构可靠性  复合材料  纤维缠绕  固体火箭发动机  失效概率

Key words:  Structural reliability  Composite materials  Filament winding  Solid rocket motor  Failure probability

摘要:

为了更加科学有效地评估纤维缠绕复合材料结构的可靠性，根据复合材料渐进失效特点，应用结构系统可靠性理论和方法，将复合材料视为连续体的结构系统，基于复合材料有限元模型对“单元”和“系统”进行了定义，构建了概率渐进失效分析的基本流程，提出了主要失效序列和结构整体的失效概率的精确解算式和近似计算方法。为解决复杂结构系统主要失效序列识别耗时巨大，甚至不可能实现的问题，提出了快速分枝-界限法、临界组群（组件）失效、最弱链模型、分枝点的确定性初步筛选等技术方法。以固体火箭发动机纤维缠绕壳体为典型应用对象，首先运用渐进失效分析方法对纤维缠绕壳体进行了有限元分析和实验验证，然后基于验证的有限元模型，应用本文所提方法，对其进行了概率渐进失效分析和结构整体失效概率的计算，结果与建立方法的假设一致，验证了本文方法的科学性和有效性。

Abstract:

The failure of composite materials is a process of gradual accumulation of damage， which belongs to a typical statically indeterminate system. Therefore， composite materials must be regarded as a structural system from the viewpoint of systems engineering. In order to evaluate the reliability of filament wound composite structures more scientifically and effectively， the load bearing reliability of composite materials is modeled and evaluated by using the theory and method of structural system reliability. Based on the finite element model of composite materials， the ‘element’ and ‘system’ are defined， and the basic flow of probabilistic progressive failure analysis is established. The exact solution formula and approximate calculation method for the main failure sequence and the failure probability of the whole structure are proposed. To solve the problem that the identification of major failure sequences in complex structural systems is time-consuming or even impossible， some technical methods， such as fast branching-bound method， critical group （component） failure， the weakest chain model and deterministic preliminary screening for branch points etc.， are proposed. Solid rocket motor filament wound case is taken as a typical application object for example examination and verification. Firstly，progressive failure analysis method is used to filament wound case finite element analysis and experimental verification， and then based on validated model of the finite element， the method proposed in this paper is applied to analyze probabilistic progressive failure process and calculate the overall structural failure probability. The result is consistent with the assumptions of the established method， the scientific nature and effectiveness of this method have been verified.