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。

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.