Aerospace composites mechanical damage prediction through multi-scale modelling

20世纪60年代，复合材料的引入取代了金属航空航天部件，S提供了更轻飞机的希望。更轻的飞机消耗更少的燃料，这为飞机制造商提供了竞争优势，并减少了污染排放，这对确保地球的可持续发展至关重要。然而，加拿大飞机的重量节省从0%到5%，而资深航空航天复合材料专家认为，使用新复合材料可以安全地减少15%左右的重量，甚至更多。令人望而却步的认证成本和过于保守的安全系数是造成这种糟糕表现的原因之一。*准确的复合材料损伤预测模型可以显著降低复合材料部件的重量，因为：i)一些认证测试可以被预测取代，这将加速引入性能更好的更新材料；ii)准确的模型将导致较低的安全系数，从而使飞机变得更轻。对复合材料的全球失效试验表明，目前的模型不能在每个载荷情况下以合理的精度预测复合材料的失效。复合材料损伤是一个由亚微米级裂纹扩展而成的复杂过程。经典的连续介质力学不适合处理这些不连续性。*建议的研究计划旨在开发一个多尺度的复合材料失效预测框架，同时研究：i)识别相关材料参数的实验方法，ii)预测复合材料损伤起始和扩展的模型，以及iii)提供有效的复合材料损伤预测的数值策略。该程序依赖于周期动力学，这是一个相对较新的连续介质力学公式，避开了大多数经典方法的缺点。*这项研究将由4名博士生和1名博士后研究员进行，13名本科生和1名研究助理将提供支持。大多数研究生将由具有互补专业知识(实验、理论和数值)的教授共同指导。每个博士生将在国际知名专家那里进行一次短期(2-3周)的实习，并在一家航空航天公司实习四个月，这是一个旨在提高研究生航空航天行业准备水平的更大培训计划的一部分。*该计划应该触发必要的范式转变，以适当地解决复合材料的损伤预测问题，从而充分发挥复合材料的减重潜力。该方法是为航空航天行业量身定做的，以加快向下一代专家的转移，这些专家将在整个项目中为这一目标接受专门培训。*

The replacement of metallic aerospace parts by the introduction of composites in the 1960's offered the promises of lighter aircraft. Lighter aircraft consume less fuel, which provides a competitive advantage to aircraft manufacturers, and reduce polluting emanations, which is essential to ensure Earth's sustainability. Yet, weight savings in Canadian aircraft range from 0 to 5%, whereas senior aerospace composites experts believe that it could safely be around 15%, and beyond with new composites. Prohibitively expensive certification costs and over-conservative safety factors contribute to this poor performance. This situation must absolutely be remedied to maintain Canada's competitiveness in aerospace.***Accurate composites predictive damage models could significantly decrease the weight of composite parts, since: i) some certification tests could be replaced by predictions, which would accelerate the introduction newer materials of improved performance and ii) accurate models will lead to lower safety factors, and hence, to lighter aircraft. The World Wide Failure Exercise on composites revealed that current models cannot predict composite failure within reasonable accuracy for every load case. Composites damage is a complex process initiated by sub-micron cracks that propagate through the hierarchy of scales. Classical continuum mechanic is ill-suited for handling these discontinuities. ***The proposed research program aims at developing a multi-scale framework for predicting composites failure by simultaneously investigating: i) experimental methods for identifying relevant material parameters, ii) models for predicting composites damage initiation and propagation and iii) numerical strategies for delivering efficient composites damage predictions. The program relies on Peridynamics, which is a relatively new formulation for continuum mechanics that eludes most of the classical approaches' shortcomings. ***The research will be carried out by 4 PhD students and 1 post-doctoral fellow, supported by 13 undergraduate students and 1 research associate. Most graduate students will be co-supervised by professors of complementary expertise (experimental, theoretical and numerical). Every PhD student will perform a short-time (2-3 weeks) internship with well-known international experts, as well as a four-month internship in an aerospace company as part of a larger training program aiming at improving the aerospace industry readinyness level of graduate students.***This program should trigger the essential paradigm shift for properly addressing composites damage prediction, and hence reap the full weight reduction potential composites offer. The methodology is tailored for the aerospace industry to accelerate its transfer with the next generation of experts that will be specifically trained for that objective throughout the program. *** *** *** **