Strain gradient plasticity theories and their application to sheet metal forming

应变梯度塑性理论及其在板材成形中的应用

• 批准号: 341725-2006
• 负责人: Wu, PeiDong
• 金额: $ 3.64万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=399572
• 关键词: Strain; gradient; plasticity; theories; their

There has been considerable societal and government legislative pressure on the North American automotive producers to reduce the fuel consumption and exhaust gas emissions from vehicles. One of the most effective ways to achieve this is by the weight reduction that can be obtained by replacing steel with aluminum in the vehicle structure and body panels. However, aluminum has a number of perceived and real technological limitations, such as its reduced formability as compared with conventional steel. It is believed that this could be eliminated by the development of improved materials, or must be circumvented by the development of new application methods. In the last few years several techniques have been developed to fabricate laminated metal sheets of different alloy combinations. Traditional products are a compromise monolithic material to meet requirements of physical, mechanical, chemical and surface properties as well as ability to fabricate and cost. Laminating decouples these requirements to enable new materials to be developed using alloys optimized for their function in the composite. This enables the cost-effective production of alloy combinations that cannot be made conventionally. Another quick and economical route to new products is to design novel surface textures of varying scales for improved product enhancement in better optical appearance and formability. The critical deformation mechanism in the surface texturing and near interface in laminated sheet is at a length scale of only a few microns. The classical plasticity theories cannot describe material behaviour at the micron scale because their constitutive models possess no internal length scale. Improved continuum plasticity models for micron level applications have been thus developed. In this project the improved continuum plasticity models for micron level applications will be implemented into finite element models to simulate the surface texturing and plastic deformation near the interface in laminated sheet. The results of this project could be of great benefit to key industries involved in metal fabrication processes in that it will lead to cost-effective fabrication processes having optimum formability and performance characteristics as well as better optical appearance.

北美汽车生产商面临着巨大的社会和政府立法压力，要求其减少车辆的燃油消耗和废气排放。实现这一目标的最有效方法之一是通过在车辆结构和车身面板中用铝代替钢来减轻重量。然而，铝具有许多感知的和真实的技术限制，例如与常规钢相比其降低的可成形性。人们认为，这可以通过开发改进的材料来消除，或者必须通过开发新的应用方法来规避。在过去的几年中，已经开发了几种技术来制造不同合金组合的层压金属板。传统的产品是一种折衷的整体材料，以满足物理，机械，化学和表面性能以及制造能力和成本的要求。层压满足了这些要求，使新材料能够使用针对其在复合材料中的功能进行优化的合金来开发。这使得能够成本有效地生产传统上无法制造的合金组合。另一个快速和经济的新产品路线是设计不同尺度的新表面纹理，以改善产品的光学外观和可成形性。层合板表面织构和界面附近的临界变形机制是在几微米的长度尺度上。经典塑性理论的本构模型没有内部长度尺度，不能描述材料在微米尺度下的行为。改进的连续塑性模型，微米级的应用程序已被开发。在本计画中，将微米级应用之改良连续塑性模型应用于有限元素模型中，以模拟层合板之表面织构与界面附近之塑性变形。该项目的结果可能对涉及金属制造工艺的关键行业有很大的好处，因为它将导致具有最佳成形性和性能特性以及更好的光学外观的具有成本效益的制造工艺。