(完整版)含穿孔损伤复合材料层合板刚度降模型毕业设计论文

中国民航大学

本科生毕业论文

含穿孔损伤复合材料层合板刚度降模型

院系：航空工程学院专业：飞行器动力工程班级：040141 D 姓名：李伟

学号：

指导教师：卢翔二零零八年六月

基于疲劳损伤两段论的复合材料层合板刚度降模型

李伟

摘要：复合材料在静态和动态载荷作用下的损伤是十分复杂的，对损伤的精确建模是关系到复合材料力学行为描述的关键问题。精确的模型能更深刻地认识复合材料的损伤机理。本文从实际工程背景出发，利用疲劳累积损伤模型，结合疲劳损伤两段理论，对复合材料层合板的寿命问题开展了较为系统深入的研究。主要内容包括：

（1）在刚度降模型的基础上，根据疲劳损伤的两阶段理论，将复合材料的疲劳损伤划分为两个阶段。并且用两种不同的函数分段描述疲劳损伤的过程，建立了疲劳损伤演化两阶段模型。通过查阅相应的试验数据，运用多元函数的最小二乘法，得到了模型中的各个拟合参数。最后以75%的强度极限应力水平为例，对模型进行了验证。

（2）在无孔层合板疲劳累积损伤模型的基础上，运用“点应力准则”概念，提出了带圆孔复合材料层合板的疲劳累积损伤模型，定义了应力修正因子。通过查阅相关的试验数据，获得了特征点应力修正因子，并建立了该带孔板疲劳累积损伤模型。用该模型对孔径为5mm层合板的S-N(应力-寿命,S-N)曲线进行了疲劳寿命预测与验证。

关键词：复合材料刚度降疲劳损伤寿命预测S-N曲线

Stiffness reduction analysis for composite laminates with circular of laminated composite. In this paper, starting from a practical engineering background, using the fatigue accumulation damage theory, together with the two-stage theory for fatigue damage, a in-depth study for the fatigue life ofcomposite laminates are carried on. The research work in this paper is included following:

1、On the basis of the stiffness reduction model, According to the

two-stage fatigue damage theory, a damage process is divided into two stage。In order to express the fatigue damage accurately, the two-stage model for fatigue accumulation damage is presented. Through accessing to the corresponding test data, using of the least squares method for multi-function, the parameters in the model are finally got.

In the end, the fatigue tests of the composite materials under 75% ultimate strength are investigated experimentally.

Based on the stiffness reduction model of imperforate composite laminates, using the concept of “characteristic dimension”stress, a fatigue model is presented for the fatigue of notched laminates, and the concept of the

correct factor is also defined. The fatigue test of notched laminates with

different diameters is refered to abtain the correct factor and the model of

notched laminates. T; fatigue damage; life prediction; S-N curve

目录

第1章概述 ...........................................................

1.1引言..............................................................

1.2复合材料疲劳特性研究方法...........................................

1.3累积损伤理论回顾...................................................

1.3.1 剩余寿命模型..................................................

1.3.2 剩余强度模型..................................................

1.3.3 剩余刚度模型..................................................

1.3.4 耗散能模型....................................................

1.3.5 Markov链损伤扩展模型..........................................

1.3.6 其他模型......................................................

1.4本文研究方法.......................................................第2章复合材料层合板疲劳寿命分析模型的建立. (1)

2.1刚度降模型简介 (1)