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: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=498946
• 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.

该研究计划的目标是提出实验和建模方法，以基于断裂力学和使用基于模态声发射新方法（MAE）的波模传播监测疲劳裂纹萌生来确定复合材料中损伤开始的耐久性极限[3-8]。通过对导波模式传播和信号内容的分析，将开发该方法来确定与复合材料中分层和裂纹萌生相关的耐久性极限，作为循环载荷以及与温度和湿度相关的环境条件的函数。 将使用分析和数值建模工具来预测分层的发生和发展。起始分层的裂纹扩展将通过虚拟裂纹闭合技术和内聚区方法进行建模。将提出实验程序和分析模型，以确定由分层引发和传播引起的复合材料刚度损失，并测量各种模式 I/模式 II 比率以及纯模式 I 和模式 II 载荷下的分层韧性。将使用断裂力学方法评估混合模式弯曲 (MMB) 测试配置的总应变能释放率 G 及其模式 I (GI) 和模式 II (GII) 分量。韧性测试结果和与裂纹萌生相关的模态声发射数据将用于定义复合材料的分层萌生标准包络线。这些失效包络线将能够预测复合材料中的分层开始。