基于贝叶斯理论的含开孔复合材料层合板剩余强度评估方法研究
发布时间：2018-11-20 08:07
【摘要】：碳纤维复合材料逐渐成为了航空航天领域中重要的材料之一,从一开始用于飞机中的次要部件,到现在大量使用与主承力结构中,复合材料体现着它在工业上的重要地位。但飞机的结构复杂,并且由于布线和维修等原因,其承载部件不得不面临开孔的问题,而应力集中现象的存在,开孔会对承载部件的力学性能造成极大的削弱。同时,复合材料力学性能具有显著的分散性,因此我们除了需要对含开孔部件进行正确的剩余强度评估以外,还需要对其进行合理的安全性与可靠性的评估。因而,对使用复合材料制备的承载构件做出合理的可靠性、剩余强度、损伤容限设计与分析是航空航天器械中承载部件力学性能评价中尤为重要的环节。剩余强度评价是含开孔复合材料层合板力学性能分析中最重要的环节。传统的评价方法往往要么只对剩余强度-开孔尺寸进行研究,而忽略复合材料自身力学性能分散性显著的问题;要么只对某一固定尺寸的开孔进行多次试验,未能全面地评价含有不同开孔尺寸复合材料层合板的性能分布和可靠性问题。因此,在开孔复合材料的强度设计问题上大多数时候依然采用“见招拆招”的研究方法。基于国内对含开孔复合材料剩余强度研究的现状与技术水平,并参考国外先进复合材料可靠性技术评价流程,本文将开孔复合材料的剩余强度评估与复合材料强度性能分散性评价结合起来,提出一种创新性的算法。基于有限的剩余强度试验数据,本文以有限元仿真计算的强度为基点拟合的函数作为复合材料剩余强度的分析基准,利用贝叶斯理论对含开孔复合材料层合板的剩余强度进行理论上的评估,并给出剩余强度参数的分布规律;然后利用马尔科夫链-蒙特卡罗(MCMC)方法对复合材料层合板的剩余强度进行数值评估,为复合材料剩余强度概率化评估提供了一种比较普适的求解方法,对复合材料层合板的开孔剩余强度问题进行全面的评价和表述,给出一个剩余强度分布规律关于开孔尺寸的关系描述,并对含开孔复合材料结构的强度百分比分位值以开孔尺寸为自变量的函数形式进行刻画,从而定性、定量地为含开孔复合材料承载结构的强度设计提供可靠的分析过程和算法依据。含开孔复合材料剩余强度分布的研究是飞机承载部件可靠性分析的基础课题之一,是后续研究的必经之路。只有在完成这一项成果后,飞机部件、结构以及整体的安全性、可靠性、损伤容限才能得到全面的分析和保障,飞机中的部件与结构的强度等力学性能设计才能得到合理而全面的指导。
[Abstract]:Carbon fiber composites (CFRP) have gradually become one of the most important materials in the field of aeronautics and astronautics. From the beginning they were used as minor parts in aircraft, and now they are widely used in the structure of main bearing force, the composite material embodies its important position in industry. However, the structure of aircraft is complex, and because of wiring and maintenance, its bearing parts have to face the problem of opening holes, and the existence of stress concentration phenomenon will greatly weaken the mechanical properties of the bearing parts. At the same time, the mechanical properties of the composites have obvious dispersion, so we need to evaluate the safety and reliability of the components with holes in addition to the correct residual strength evaluation. Therefore, the reasonable reliability, residual strength, damage tolerance design and analysis of the load-bearing components made of composite materials are particularly important in the evaluation of mechanical properties of the load-bearing components in aerospace equipment. The evaluation of residual strength is the most important link in the analysis of mechanical properties of composite laminates with open holes. The traditional evaluation methods usually only study the residual strength and the size of the open hole, but ignore the obvious dispersion of the mechanical properties of the composites. The performance distribution and reliability of composite laminates with different sizes can not be comprehensively evaluated by several tests on a fixed size of the composite laminates. Therefore, in the strength design of porous composite materials, the research method is still adopted in most of the time. Based on the present situation and technical level of domestic research on residual strength of composite materials with open holes, and referring to the evaluation flow of advanced reliability technology of composite materials abroad, In this paper, an innovative algorithm is proposed by combining the residual strength evaluation of the porous composites with the dispersion evaluation of the strength properties of the composites. Based on the finite residual strength test data, this paper uses the function of the finite element simulation calculation as the basic point fitting function as the analysis benchmark of the composite residual strength. Bayesian theory is used to evaluate the residual strength of composite laminates with holes and the distribution of residual strength parameters is given. Then the Markov chain-Monte Carlo (MCMC) method is used to evaluate the residual strength of composite laminates, which provides a general solution for the probabilistic evaluation of composite residual strength. In this paper, the problem of open hole residual strength of composite laminates is comprehensively evaluated and expressed, and the relation between the distribution of residual strength and the size of open hole is given. And the functional form of the strength percentage quantile of the composite structure with open hole size as independent variable is described, so as to qualitatively characterize the strength percentage quantile value of composite structure with open hole. It provides reliable analysis process and algorithm basis for strength design of composite bearing structure with open hole. The study of residual strength distribution of composite materials with open holes is one of the basic problems in reliability analysis of aircraft bearing parts and is the only way to follow up research. Only after this achievement can the safety, reliability and damage tolerance of aircraft components, structures and the whole be fully analyzed and guaranteed. The design of mechanical properties such as the strength of components and structures in aircraft can be guided reasonably and comprehensively.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332
本文编号：2344342
[Abstract]:Carbon fiber composites (CFRP) have gradually become one of the most important materials in the field of aeronautics and astronautics. From the beginning they were used as minor parts in aircraft, and now they are widely used in the structure of main bearing force, the composite material embodies its important position in industry. However, the structure of aircraft is complex, and because of wiring and maintenance, its bearing parts have to face the problem of opening holes, and the existence of stress concentration phenomenon will greatly weaken the mechanical properties of the bearing parts. At the same time, the mechanical properties of the composites have obvious dispersion, so we need to evaluate the safety and reliability of the components with holes in addition to the correct residual strength evaluation. Therefore, the reasonable reliability, residual strength, damage tolerance design and analysis of the load-bearing components made of composite materials are particularly important in the evaluation of mechanical properties of the load-bearing components in aerospace equipment. The evaluation of residual strength is the most important link in the analysis of mechanical properties of composite laminates with open holes. The traditional evaluation methods usually only study the residual strength and the size of the open hole, but ignore the obvious dispersion of the mechanical properties of the composites. The performance distribution and reliability of composite laminates with different sizes can not be comprehensively evaluated by several tests on a fixed size of the composite laminates. Therefore, in the strength design of porous composite materials, the research method is still adopted in most of the time. Based on the present situation and technical level of domestic research on residual strength of composite materials with open holes, and referring to the evaluation flow of advanced reliability technology of composite materials abroad, In this paper, an innovative algorithm is proposed by combining the residual strength evaluation of the porous composites with the dispersion evaluation of the strength properties of the composites. Based on the finite residual strength test data, this paper uses the function of the finite element simulation calculation as the basic point fitting function as the analysis benchmark of the composite residual strength. Bayesian theory is used to evaluate the residual strength of composite laminates with holes and the distribution of residual strength parameters is given. Then the Markov chain-Monte Carlo (MCMC) method is used to evaluate the residual strength of composite laminates, which provides a general solution for the probabilistic evaluation of composite residual strength. In this paper, the problem of open hole residual strength of composite laminates is comprehensively evaluated and expressed, and the relation between the distribution of residual strength and the size of open hole is given. And the functional form of the strength percentage quantile of the composite structure with open hole size as independent variable is described, so as to qualitatively characterize the strength percentage quantile value of composite structure with open hole. It provides reliable analysis process and algorithm basis for strength design of composite bearing structure with open hole. The study of residual strength distribution of composite materials with open holes is one of the basic problems in reliability analysis of aircraft bearing parts and is the only way to follow up research. Only after this achievement can the safety, reliability and damage tolerance of aircraft components, structures and the whole be fully analyzed and guaranteed. The design of mechanical properties such as the strength of components and structures in aircraft can be guided reasonably and comprehensively.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332
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