Heat Assisted Local Forming and Joining Processes: Simulation and Experimentation

热辅助局部成型和连接工艺：模拟和实验

• 批准号: RGPIN-2019-05972
• 负责人: Champliaud, Henri
• 金额: $ 2.84万
• 依托单位: École de technologie supérieure
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=687341
• 关键词: Heat; Assisted; Local; Forming; Joining

The increasing demand in the automotive and aerospace industries for higher properties in their manufactured parts is closely connected to the lower thickness of the sheet metal that could be involved in the forming processes and consequently the lighter weights of these parts at the end. The main concern is the poor formability of high grade materials, especially at room temperature. For this reason, many efforts are actually made towards warm to high temperature sheet metal manufacturing processes but there is still an important gap between the prediction of the numerical models and the actual processes because of the complex evolution of the microstructure during forming at elevated temperature. One aspect following a heat assisted forming process is the transformation induced plasticity effect (TRIP) in the microstructure that can occur in phase changing materials. Higher hardening capability are exhibited following this transformation and one can take an advantage of the enhanced properties of the manufactured parts to decrease furthermore their thicknesses for weight reduction and then improved fuel efficiency in transportation. A typical example of a dynamic heat assisted forming process involving hard-to-shape high strength materials is the sheet-metal spinning for aerospace applications. The process progressively transform flat metal blank into hollow shapes, mainly with axisymmetric profiles. The method uses a tool i.e. a roller which forces a metal blank onto a revolving mandrel. The roller is pressed against the blank and is moved axially into complex trajectories to achieve finally a hollow-shaped product. With the great number of parameters (speed, temperature dependent properties, strain rate, tool trajectories, induced anisotropy) involved in the procedure a comprehensive design of experiments would be too demanding in terms of costs and dedicated time. Finite element models are of great help to reproduce complex processes and can offer very in deep details on the ongoing forming process and the final properties of the parts. The key is the accurate information input in the numerical model and its ability to reproduce precisely the heat transfer, the strain hardening, the anisotropy and eventually the TRIP phenomena. In this project, the focus will be on the simulation model and its ability to represent these phenomena evolving with time in the material. A crystal plasticity model will be implemented in the finite element analysis to follow these complex evolutions. Eventually, phase transformation could be monitored with the appropriate amount of locally heat input at the forming tool contact zone to enhance the sheet metal formability. The goal is to bring conventional forming processes to new technological levels by adding high tech heating sources (like laser heating) in the forming steps of hard to shape high strength materials, enhancing material properties and maintaining heat assisted operation at lowest cost as possible.

汽车和航空航天行业对其制造零件中较高性能的需求不断增长，与可能涉及形成过程的钣金厚度紧密相关，因此最终这些部分的重量更轻。主要问题是高级材料的形成性差，尤其是在室温下。因此，实际上为高温至高温金属制造工艺而做出了许多努力，但是由于数值模型的预测和实际过程之间仍然存在一个重要的差距，因为在高温下形成过程中微观结构的复杂演化。热辅助形成过程之后的一个方面是在变化材料中可能发生的微观结构中的转化诱导可塑性效应（TRIP）。这种转化后，表现出更高的硬化能力，并且可以利用制成部分的增强性能，从而减小其厚度以减轻体重，然后提高运输燃油效率。涉及难以形成高强度材料的动态热辅助形成过程的一个典型例子是航空航天应用的薄板金属旋转。该过程逐渐将扁平金属毛坯转化为空心形状，主要具有轴对称轮廓。该方法使用工具，即将金属毛坯迫使旋转式mandrel上的滚筒。将滚筒压在空白上，并将轴向移动到复杂的轨迹中，以达到最终的空心产物。随着参数的大量参数（速度，温度依赖性特性，应变率，刀具轨迹，诱导的各向异性）涉及该过程的全面设计在成本和专用时间方面，实验的全面设计太要求了。有限的元素模型有助于重现复杂的过程，并且可以在正在进行的形成过程和零件的最终属性的深处提供。关键是数值模型中的准确信息输入及其精确再现热传递，应变硬化，各向异性及最终Trip现象的能力。在这个项目中，重点将放在模拟模型及其代表这些现象随着材料中时间演变而来的能力。在有限元分析中将实现晶体可塑性模型，以遵循这些复杂的演变。最终，可以通过在形成工具接触区域的适当局部热量输入来监视相变，以增强金属的形成性。目的是通过在难以塑造高强度材料，增强材料特性并以最低成本以最低成本的最低成本中添加高科技加热来源（例如激光加热），将常规形成过程提升到新的技术水平。