碳纤维增强复合材料多向层板疲劳分层扩展行为研究

Delamination is a common damage mode in composite laminates. Delamination growth behavior of multidirectional composites under fatigue loads is a hot issue in the field of composite mechanics. The existed fatigue delamination growth models by fitting experimental data are limited to the analysis of practical structures. This project aims to 1) decompose the control parameter of the fatigue delamination growth rate in twofold aspects: the fatigue delamination growth resistance and fatigue delamination growth driving force; 2) present a fatigue delamination resistance parameter and establish its mechanics model based on the physical mechanisms of the fatigue delamination growth resistance; 3) establish mechanics models of the fatigue delamination growth driving force; 4) further develop fatigue delamination growth models with wide applicability, simple form and explicit physical meaning. To realize the objectives, experiments for measuring both the fatigue delamination growth rate and the fatigue delamination resistance are designed using CFRP laminates with multidirectional interfaces, which will be fabricated by two material systems. The experiments will be carried out under a variety of stress ratios and mixing ratios. Along with the microstructure analysis on the delaminated interface of specimens, the mechanics mechanisms that cause the fatigue delamination growth resistance and drive the fatigue delamination growth will be revealed for multidirectional composites. The mechanics models of the fatigue delamination resistance and the fatigue delamination growth rate will be verified. Additionally, advanced numerical methods including the VCCT, CZM, and XFEM will be used for simulating the delamination of multidirectional CFRP laminates under complex loading conditions at both the macroscopic and microscopic scales, following which the fatigue life and residual strength of CFRP laminates containing initial flaws can be predicted.

分层是复合材料层板常见损伤形式。疲劳载荷下复合材料多向层板分层扩展是复合材料力学的热点问题之一。现有基于实验数据拟合的疲劳分层扩展模型适应范围有限，难以应用于实际结构分析。本项目拟解耦疲劳分层扩展速率控制参量，从分层扩展阻力和分层扩展驱动力两个方面分别研究，建立符合分层扩展阻力物理机制的疲劳分层阻力力学模型和疲劳扩展驱动力模型，进而建立形式简洁、物理意义明确而又广泛适用的疲劳分层扩展模型。将开展两种材料体系CFRP层板多种界面、多种应力比、多种混合比的疲劳分层扩展实验和疲劳分层阻力测定实验，结合分层界面微观形貌分析，揭示疲劳分层阻力的形成机制和疲劳分层扩展驱动力的作用机制，验证疲劳分层阻力的力学模型和疲劳分层扩展模型。还将采用VCCT、内聚力模型、扩展有限元等先进数值方法进行宏、细观尺度CFRP多向层板在复杂加载状态下的分层扩展模拟，实现含初始分层缺陷CFRP层板的疲劳寿命和剩余强度预测。

针对现有基于实验数据拟合的复合材料疲劳分层扩展模型适应范围有限，难以应用于实际结构分析的问题，本项目从分层扩展阻力和分层扩展驱动力两个方面解耦疲劳分层扩展速率控制参量，建立符合分层扩展阻力物理机制的疲劳分层阻力力学模型和疲劳扩展驱动力模型，进而建立形式简洁、物理意义明确而又广泛适用的疲劳分层扩展模型。本项目开展两种材料体系CFRP层板多种界面、多种应力比、多种混合比的疲劳分层扩展实验和疲劳分层阻力测定实验，结合分层界面微观形貌分析，揭示疲劳分层阻力的形成机制和疲劳分层扩展驱动力的作用机制，验证疲劳分层阻力的力学模型和疲劳分层扩展模型。最后，采用虚拟裂纹闭合技术、内聚力模型、扩展有限元等先进数值方法进行宏、细观尺度CFRP多向层板在复杂加载状态下的分层扩展模拟，实现含初始分层缺陷CFRP层板的疲劳寿命和剩余强度预测。研究结果可用于工程复合材料结构的损伤容限设计和分析领域。