Aerospace composites mechanical damage prediction through multi-scale modelling

20世纪60年代，复合材料取代了航空航天的金属部件，为飞机的轻型化提供了希望。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性至关重要。然而，加拿大飞机的重量减轻范围从0到5%，而高级航空复合材料专家认为，使用新的复合材料，重量减轻可以安全地达到15%左右。昂贵的认证费用和过于保守的安全因素导致了这种糟糕的性能。这种情况绝对必须得到纠正，以保持加拿大在航空航天领域的竞争力。精确的复合材料预测损伤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所取代，这将加速引入性能改进的新材料; ii）精确的模型将导致更低的安全系数，从而使飞机更轻。全球范围内的复合材料失效演习表明，目前的模型不能预测复合材料失效在合理的精度为每一个负载情况。复合材料的损伤是一个复杂的过程，它是由亚微米尺度的裂纹在尺度上扩展引起的。经典连续介质力学不适合处理这些不连续性。 * 拟议的研究计划旨在开发一个多尺度框架，用于预测复合材料失效，同时调查：i）识别相关材料参数的实验方法，ii）预测复合材料损伤开始和传播的模型和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Peridendics，这是一个相对较新的连续介质力学的公式，避免了大多数经典方法的缺点。* 该研究将由4名博士生和1名博士后研究员进行，由13名本科生和1名研究助理提供支持。大多数研究生将由互补专业知识（实验，理论和数值）的教授共同监督。每个博士生将与知名国际专家进行短期（2-3周）实习，以及在航空航天公司进行为期四个月的实习，作为旨在提高研究生航空航天工业准备水平的大型培训计划的一部分。这一计划应该触发基本的范式转变，正确解决复合材料损伤预测，从而获得充分的重量减轻复合材料提供的潜力。该方法是专为航空航天工业量身定制的，以加速其与下一代专家的转移，这些专家将在整个计划中为此目标进行专门培训。*** *** *** **

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. *** *** *** **