Falzon Brian G
School of Engineering, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia.
Advanced Composites Research Group, School of Mechanical and Aerospace Engineering, Queen's University Belfast, BelfastBT9 5AH, UK.
Philos Trans A Math Phys Eng Sci. 2022 Sep 19;380(2232):20210336. doi: 10.1098/rsta.2021.0336. Epub 2022 Aug 1.
The use of lightweight carbon fibre-reinforced polymer (CFRP) composites in transportation vehicles has necessitated the need to guarantee that these new materials and their structures are able to deliver a sufficient level of crashworthiness to ensure passenger safety. Unlike their metallic counterparts, which absorb energy primarily through plastic deformation, CFRPs absorb energy through a complex interaction of damage mechanisms involving matrix (polymer) cracking, fibre/matrix debonding, fibre pull-out/kinking/fracture, delamination and inter/intralaminar friction. CFRP is primarily deployed as a laminate and can potentially deliver a higher specific energy absorption than metals. Translating this capability to a structural scale requires careful design and is dependent on geometry, fibre architecture, laminate stacking sequence and damage initiation strategies for optimal uniform crushing. Consequently, the design of crashworthy CFRP structures currently entails extensive physical testing which is expensive and time consuming. This paper reports on progress and challenges in the development of a finite-element computational capability for simulating the crushing of composites for crashworthiness assessments, with the aim of reducing the burden of physical testing. It addresses the 'tyranny of scales' in modelling structures constructed of CFRP composites. Intrinsic to this capability is the acquisition of reliable material data for the damage model, in particular interlaminar and intralaminar fracture toughness values. While quasi-static values can be obtained with a reasonable level of confidence, results achieved through dynamic testing are still the subject of debate and the relationship between fracture toughness and strain rate has yet to be satisfactorily resolved. This article is part of the theme issue 'Nanocracks in nature and industry'.
在运输车辆中使用轻质碳纤维增强聚合物（CFRP）复合材料，使得必须确保这些新材料及其结构能够提供足够的抗撞性以保障乘客安全。与主要通过塑性变形吸收能量的金属材料不同，CFRP通过包括基体（聚合物）开裂、纤维/基体脱粘、纤维拔出/扭结/断裂、分层以及层间/层内摩擦在内的损伤机制的复杂相互作用来吸收能量。CFRP主要以层压板形式使用，并且有可能比金属具有更高的比能量吸收率。将这种能力转化为结构规模需要精心设计，并且取决于几何形状、纤维结构、层压板堆叠顺序以及用于实现最佳均匀挤压的损伤起始策略。因此，目前设计具有抗撞性的CFRP结构需要进行大量的物理测试，这既昂贵又耗时。本文报道了在开发用于模拟复合材料挤压以进行抗撞性评估的有限元计算能力方面的进展和挑战，目的是减轻物理测试的负担。它解决了在对由CFRP复合材料构建的结构进行建模时的“尺度难题”。这种能力的内在要求是获取用于损伤模型的可靠材料数据，特别是层间和层内断裂韧性值。虽然可以有合理的把握获得准静态值，但通过动态测试获得的结果仍存在争议，并且断裂韧性与应变率之间的关系尚未得到令人满意的解决。本文是主题为“自然与工业中的纳米裂纹”的一部分。
