Friction Stir Blind Riveting for Dissimilar Materials

该奖项支持对通过摩擦搅拌盲铆接不同材料的新型单面连接工艺的基础研究。研究的目标是建立热机械输入、材料性能、微观结构特征和由此产生的接头强度之间的联系。具体地说，本研究将建立基于物理的摩擦旋转铆钉内力和扭矩的热力学模型，并对模型进行实验验证；检验粘塑性材料响应可以模拟搅拌摩擦铆接金属变形的假设；研究工艺条件对材料流动、缺陷形成和接头强度的影响；分析微观组织演变及其对接头失效机制的影响；确定不同的热机械影响区；以及评估不同连接材料的摩擦搅拌机理。研究结果将提供知识和理解，以满足汽车行业采用先进轻质材料的关键需求。在汽车中加入这些轻质材料的能力对于提高燃油经济性和减少对环境的影响至关重要。这项技术结合了搅拌摩擦焊的优点和盲铆钉的强度。这项研究将推进这种新的连接技术，适用于从金属到复合材料的各种不同材料。研究成果也将对其他运输行业产生广泛影响，如航空航天、铁路和造船，在这些行业，对不同重量或功能的连接材料的需求越来越大，但受到传统连接技术的限制。该项目将促进工业从业者的积极学习，并扩大夏威夷代表性不足的学生群体的参与。研究成果将被整合到本科生/研究生课程开发和K12教育实践模块中。

This award supports fundamental research on a novel one-sided joining process of dissimilar materials through friction stir blind riveting. The research objective is to establish the link among the thermomechanical inputs, material properties, microstructural characteristics, and resulting joint strength. Specifically, the research will formulate a physics-based thermo-mechanical model for intrinsic forces and torques with frictionally rotated rivet and validate the model experimentally; test the hypothesis that viscoplastic type material response can simulate metal deformation in friction stir blind riveting; investigate the effects of process conditions on material flow, defect formation, and joint strength; analyze microstructure evolution and its impacts on joint failure mechanisms; identify different thermomechanically affected zones; and assess the friction stir mechanisms for different joining materials. Research results will provide knowledge and understanding to meet the critical need for the incorporation of advanced lightweight materials in the automotive industry. The capability to incorporate these lightweight materials in an automobile is crucial for improving fuel economy and reducing environmental impact. This technology combines the benefits of friction stir welding with the strength of blind rivets. The research will advance this new joining technique for a wide range of dissimilar materials, from metals to composites. Research findings will also have a broad impact on other transportation industries, such as aerospace, rail, and shipbuilding, where joining materials with different weights or functionalities is increasingly demanded but limited by traditional joining techniques. This project will promote active learning for industrial practitioners, and broaden participation of underrepresented student groups in Hawaii. The research outcomes will be integrated into undergraduate/graduate course development, and hands-on modules for K12 education.