Flaw growth thresholds in composites

复合材料中的缺陷增长阈值

• 批准号: 418920-2011
• 负责人: Ngô, AnhDung
• 金额: $ 10.2万
• 依托单位: École de technologie supérieure
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=551590
• 关键词: Flaw; growth; thresholds; composites

The objective of this research program is to propose experimental and modeling methodologies to determine endurance limit for damage onset in composite based on fracture mechanics and fatigue crack initiation monitoring using wave mode propagation based on Modal Acoustic Emission new approaches (MAE) [3-8]. Through an analysis of the guided wave mode propagation and signal contents, the approach will be developed to determine the endurance limit related to the onset of delamination and cracks initiation in composite materials, as function of cyclic loading and environmental conditions related to temperature and humidity. Analytical and numerical modeling tools will be performed to predict delamination onset and growth. Crack propagation of the starting delamination will be modeled by the Virtual Crack Closure Technique and Cohesive Zone method. Experimental procedures and analytical model will be proposed to determine composite stiffness loss induced by delamination initiation and propagation, and to measure delamination toughness over a wide range of mode I / mode II ratios as well as for pure mode I and mode II loadings. The total strain energy release rate G and its mode I (GI) and mode II (GII) components will be evaluated for the mixed-mode bending (MMB) test configuration using a fracture mechanics approach. Toughness test results and modal acoustic emission data related to crack initiation will be used to define the delamination initiation criteria envelope for the composite. These failure envelopes will enable predictions of delamination onset in composite materials.

本研究计划的目的是提出实验和建模方法，以确定基于断裂力学的复合材料损伤发生的持久极限，并使用基于模态声发射新方法（MAE）的波模式传播监测疲劳裂纹起裂[3-8]。通过对导波模式传播和信号内容的分析，该方法将被开发来确定与复合材料中分层和裂纹萌生有关的耐久性极限，作为循环加载和与温度和湿度相关的环境条件的函数。分析和数值模拟工具将用于预测分层的发生和生长。采用虚拟裂纹闭合技术和内聚区方法对开始分层的裂纹扩展过程进行建模。将提出实验程序和分析模型，以确定由分层开始和扩展引起的复合材料刚度损失，并测量大范围I / II型比以及纯I型和II型载荷下的分层韧性。总应变能释放率G及其I型（GI）和II型（GII）分量将使用断裂力学方法对混合弯曲（MMB）测试配置进行评估。与裂纹起裂有关的韧性测试结果和模态声发射数据将用于定义复合材料的分层起裂标准包络。这些失效包层可以预测复合材料中分层的发生。