Environmental effects on the durability of advanced composite materials

环境对先进复合材料耐久性的影响

• 批准号: DDG-2015-00004
• 负责人: LaPlante, Gabriel
• 金额: $ 0.73万
• 依托单位: Université de Moncton
• 依托单位国家: 加拿大
• 项目类别: Discovery Development Grant
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612409
• 关键词: Environmental; effects; durability; advanced; composite

Advanced composite parts are fabricated by stacking plies of resin-impregnated fibres and curing under high temperature and pressure. Since the number and orientation of the plies are design variables, the part and the material are being designed simultaneously. Composites offer new possibilities to manufacturers to fabricate high performance, corrosion resistant, lightweight structures, but they have not yet reached their full potential in structures due to lingering uncertainty about their degradation and failure mechanisms. Research is paramount to support the development of the multi-billion dollar composite industry. The overall objective of the proposed research program is to develop a comprehensive understanding of the moisture degradation of composites and to predict its long-term effects on the integrity of structures in real world applications. Understanding the deterioration of composites is important to ensure proper inspection and maintenance of aging structures currently in service and to adopt the best possible methodologies in future design. Some aspects of moisture degradation have been investigated in our previous work such as the mechanics of moisture absorption, moisture effects on the properties of epoxy, and moisture effects on delamination growth in composites. More avenues must be explored to fully understand progressive damage in composites exposed to wet environments. In service, low-velocity impacts from blunt objects, like a dropped tool, can create internal damage to a laminated composite that is invisible from the surface. Subsequent loading can cause damage growth leading to delamination, which may progress undetected until complete failure of a structure. Models have been proposed to predict damage induced by low-velocity impact but the combined effects of impact and moisture exposure, and their consequences on the residual strength and life of a composite structure remain vastly unexplored. In this program, a methodology will be developed to understand and predict impact damage formation and growth in wet composites. Impact damage may involve fibre breakage, matrix cracking and/or fibre-matrix debonding. Moisture, by altering the matrix and the fiber-matrix interface, may change the fracture process and adversely affect the damage tolerance of a composite. Impact damage will be examined by thorough inspection of laboratory produced damaged samples. Failure criteria will be evaluated to determine which ones better predict damage initiation and progression. It is intended to combine damage mechanics, failure criteria and fracture mechanics in numerical models that will simulate the complete composite failure process from impact to final fracture with the inclusion of moisture effects. The results of this research will benefit the aerospace industry by paving the way to the implementation of a damage tolerance philosophy to composites.

先进的复合材料部件是通过堆叠树脂浸渍纤维层并在高温高压下固化而制成的。由于铺层的数量和方向是设计变量，因此零件和材料是同时设计的。复合材料为制造商制造高性能、耐腐蚀、轻质结构提供了新的可能性，但由于其降解和失效机制的不确定性，复合材料在结构中尚未充分发挥其潜力。研究对于支持价值数十亿美元的复合材料行业的发展至关重要。拟议的研究计划的总体目标是发展的复合材料的水分降解的全面了解，并预测其对结构的完整性在真实的世界应用的长期影响。了解复合材料的劣化对于确保对当前服役的老化结构进行适当的检查和维护以及在未来的设计中采用最佳的方法是很重要的。在我们以前的工作中，已经研究了水分降解的一些方面，如吸湿力学，水分对环氧树脂性能的影响，以及水分对复合材料中分层生长的影响。必须探索更多的途径来充分了解暴露在潮湿环境中的复合材料的渐进损伤。在使用中，来自钝物的低速冲击，如掉落的工具，可以对层压复合材料产生从表面看不见的内部损伤。随后的加载会导致损伤增长，导致分层，这可能会在未被发现的情况下进行，直到结构完全失效。已经提出了模型来预测由低速冲击引起的损伤，但是冲击和水分暴露的组合效应，以及它们对复合结构的剩余强度和寿命的后果仍然是未知的。在该计划中，将开发一种方法来了解和预测湿复合材料中冲击损伤的形成和生长。冲击损伤可能包括纤维断裂、基体开裂和/或纤维-基体脱粘。水分通过改变基体和纤维-基体界面，可能改变断裂过程，并对复合材料的损伤容限产生不利影响。将通过对实验室生产的受损样品进行彻底检查来检查冲击损伤。将评估失效标准，以确定哪些标准能更好地预测损伤的发生和发展。它的目的是结合联合收割机损伤力学，故障准则和断裂力学的数值模型，将模拟完整的复合材料的故障过程，从冲击到最终断裂，包括水分的影响。这项研究的结果将有利于航空航天工业铺平道路的实施损伤容限的哲学复合材料。