Post necking material testing, characterization and constitutive modelling

美国国家公路交通安全管理局、交通部（联邦机动车安全标准，FMVSS 206）要求，在设计汽车零部件时，包括车门和门锁，必须满足某些安全考虑和要求，以应对后碰撞和侧面碰撞。保护车辆乘员的一些主要设计考虑因素是通过能量吸收和/或能量转移来最大限度地减少冲击力。这包括坍塌的结构构件和泡沫填充的结构，以及折断安全锁等。**本研究的目的是了解金属材料在**失效特别是后颈化状态下的潜在力学。这包括研究材料微观结构、强度、硬化和热处理对颈缩发生的影响，在文献和行业中可用的数据有限。这将通过制定综合测试计划、材料表征和建模技术来预测此类现象来实现。由于在颈缩区域独特的局部不均匀变形，将使用先进的数字成像应变测量。然后，测试结果将用于开发能够捕捉颈缩行为的本构塑性模型。这将使用两个数值模型来实现。第一个是具有更新硬化系数的迭代塑性模型，第二个是具有空洞成核的多孔塑性模型。**建议的研究将作为工程设计的支柱，并有助于开发、选择和优化更可靠的材料和设计，从而促进广泛的应用。因此，该工具将成为知识体系的附加价值，并为加拿大工业提供创新工程的有效工具。

The National Highway Traffic Safety Administration, Department of Transportation (Federal Motor Vehicle**Safety Standards, FMVSS 206) requires that certain safety considerations and requirements are met in the**design of vehicle components including doors and door locks during rear and side impact. Some of the main**design considerations to protect vehicle occupants are to minimize the impacted force by means of energy**absorption and/or energy diversion. This includes collapsing structural members and foam filled structures, and**snapping safety locks, among others.**The objective of the proposed study is to understand the underlying mechanics of metallic materials under**failure specifically post-necking regime. This includes studying the effect of material microstructure, strength,**hardening and heat treatment on the onset of necking for which available data is limited in the literature and**industry. This will be achieved through developing an integrated test plan, material characterization and**modeling techniques to predict such phenomena. Due to the unique localized non-uniform deformation in the**necking regions, advanced strain measurements using digital imaging will be used. The test results will then be**used to develop constitutive plastic models able to capture the necking behavior. This will be achieved using**two numerical models. The first is an iterative plastic model with updated hardening coefficients and the**second using a porous plastic model with void nucleation.**The proposed study will serve as a backbone of the engineering design and aid in the development, selection**and optimization of more reliable materials and designs, benefiting a wide range of applications. This tool**would, therefore, be an added value to the body of knowledge and offer an effective tool towards innovative**engineering to the Canadian industry.