含缺陷自动铺丝复合材料构件的损伤失效机理研究

For the study of failure mechanism of composite structures with automated fiber placement induced defects, the experimental study will be carried out by using electrical measurement together with the full field non-contact optical measurement. The laminated specimens containing typical defects such as gap,overlap,gap/overlap and twisted tow will be designed and tested. According to the observed phenomenon and experimental data,the analysis model and corresponding algorithm applicable to study the damage evolution behavior and failure mechanism of such structures can be established. For the variable stiffness characteristics of the composite structure fabricated by automated fiber placement process with variable angle ply, the calculation theory and method considering variable stiffness will be developed, and the associated finite element formulation will be derived, and the code for finite element analysis will also be developed. The numerical investigation for the failure mechanism and load-carring ability under static compression based on global-local strategy can be carried out efficiently and some useful results will be obtained for the mechanical properties evaluation of composite structures with automated fiber placement induced defects. In the analysis, the relationship between the global mechanical performance and the local damage behavior will be established as well as the coupling effect between the typical defects and other normal damages.

本项目拟对含缺陷自动铺丝复合材料构件的损伤失效机理和承载能力开展研究，针对含间隙、重叠、间隙/重叠、扭曲波纹四种典型纤维铺放缺陷，开展复合材料板壳的损伤演化行为的实验研究；发展典型缺陷相应的损伤断裂力学理论，建立适用的损伤分析模型来分析其损伤演变规律和失效行为；发展变角度铺设、变刚度层合结构的刚度计算理论，提出相应的有限元分析方法；针对预设不同铺放缺陷形式的加筋板壳结构，开展其屈曲和后屈曲过程中的损伤失效行为和承载能力研究，为含缺陷自动铺丝复合材料构件的力学性能评估提供分析工具。

自动铺丝技术在复杂大曲率复合材料构件的成型方面表现出了强大的优势，为几何形状复杂的复合材料层合结构的制备提供了极大的灵活性。此外，通过曲线路径的铺设可以制造变刚度层合结构，从而充分利用复合材料各向异性材料特征，使材料分配更利于结构承载方向。采用自动铺丝技术整体制造复合材料机身无论从机身整体性能还是从材料制造技术层面来看均具有突出的优势，可能成为复合材料机身技术的一种标准。在我国大飞机工程已全面开展的背景下，发展和应用自动铺放成型技术来提高复合材料制造水平、提高效率和降低成本已是大势所趋。自动铺放技术的最终产品具有力学的不确定性，而这种力学性能的不确定性导致了纤维缺陷，含有初始缺陷的产品服役过程中在静/动载荷作用下损伤可能会出现扩展甚至导致结构的早期失效。直面时间和成本问题，尽快发展一套针对此类结构的力学性能评估和承载能力预测的理论方法和数值计算工具具有重要科学意义和工程价值。本项研究针对此项重大需求，开展了基于自动铺丝技术含工艺缺陷复合材料构件的力学性能评估和相应的结构损伤演化、破坏机制和承载能力预测方面的理论和仿真方法工作，开发了计算评估软件，为自动铺丝工艺技术的研究和应用建立了技术储备。