Towards a Micromechanical Damage Model for Lightweight Materials in Vehicle Crash

2012年美国企业平均燃油经济性(CAFé)目标要求到2025年将燃油消耗降低50%，这加大了汽车行业的研究和创新力度。为了在不损害乘员安全的情况下实现这些目标，超高强度钢、高强度铝和镁合金等下一代材料正在迅速开发，并应用于轻量化的多材料汽车结构。虽然这些材料提供了巨大的轻量化潜力，但由于其复杂的材料行为和断裂敏感性，它们也带来了不断缩小的工艺设计窗口。因此，需要在高温下进行先进的成形操作，以避免这些材料在室温下的低延展性。为了在大批量、低成本的汽车制造环境中保持竞争力，需要计算机辅助工程(CAE)来设计零部件、工装、成形工艺并预测其在汽车碰撞中的性能。这些轻质合金复杂的力学行为，再加上对先进成形操作的需要，远远超出了今天的数值模型的能力。拟议的研究将解决CAE断裂模型中的这一严重缺陷，以利用这些新兴材料系统的轻量化潜力。*这项研究的长期目标是开发一个全面的建模平台，用于模拟从制造到在役性能的产品历史，从而使多材料轻量化汽车结构的设计和商业化成为可能。短期内，该研究计划将开发创新的实验和数值方法，以预测各向异性轻质合金在成形和碰撞事件中发现的复杂非比例加载条件下的行为。这项研究的核心是发展微观机械空洞损伤模型，以取代工业中使用的物理基础有限的现象学损伤模型。为了优化结构组件和开发新的合金，材料模型必须能够解释整个过程链中微结构的演变。*使用先进材料和制造工艺设计成形工艺和部件的能力对加拿大汽车和制造业的创新和全球竞争力至关重要。这项研究计划与加拿大2014年的科学技术战略“轻量化材料和技术”直接一致，成为新的“先进制造”研究优先事项中的研究重点。这项研究将为加拿大汽车制造商提供一种尖端的研究和设计工具，可以用于从概念到碰撞以及从微观到宏观的零部件设计。

The 2012 U.S. Corporate Average Fuel Economy (CAFÉ) targets mandating a 50% cut in fuel consumption by 2025 have supercharged research and innovation within the automotive industry. To reach these targets without compromising occupant safety, next generation materials such as ultra high strength steels, high strength aluminum and magnesium alloys are being rapidly developed and implemented into a lightweight multi-material vehicle architecture. Although these materials offer tremendous potential for lightweighting, they also bring ever shrinking process design windows due to their complex material behaviour and fracture sensitivity. Consequently, advanced forming operations at elevated temperatures are required to avoid the low ductility of these materials at room temperature. To stay competitive in the high volume, low cost environment of automotive manufacturing, computer assisted engineering (CAE) is required to design the component, tooling, forming process and predict its performance in a vehicle crash. The complicated mechanical behaviour of these lightweight alloys coupled with the need for advanced forming operations far exceeds the capabilities of today's numerical models. The proposed research will address this critical shortfall in the CAE fracture models to capitalize on the potential of these emerging material systems for lightweighting. *** The long term goal of this research is the development of a comprehensive modeling platform for the simulation of product history, from manufacturing to in-service performance, to enable the design and commercialization of multi-material lightweight vehicle architectures. In the short term, the research program will develop innovative experimental and numerical methodologies to predict the behavior of anisotropic lightweight alloys in complex non-proportional loading conditions found in forming and crash events. Central to the research is the development of micromechanical void damage models that can replace the phenomenological damage models used by industry that have a limited physical basis. To optimize structural components and develop new alloys, it is imperative the material models can account for how a microstructure evolves across the process chain. *** The ability to design forming processes and components using advanced materials and manufacturing processes is critical for the innovation and global competitiveness of the automotive and manufacturing sectors in Canada. This research program is in direct alignment with Canada's 2014 Science and Technology Strategy for “Lightweight Materials and Technologies” to be a Research Focus within the new “Advanced Manufacturing” Research Priority. This research will provide Canadian automakers with a cutting edge research and design tool that can be used to design a component from its conception to crash and from the micro-to-macro-scale.