Understanding How Aluminum Moves Around a Friction Stir Welding Tool in order to Prevent Welding Defects

了解铝如何在搅拌摩擦焊工具周围移动以防止焊接缺陷

• 批准号: 1826104
• 负责人: Frank Pfefferkorn
• 金额: $ 41.2万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2022-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1826104&HistoricalAwards=false
• 关键词: Understanding; How; Aluminum; Moves; Around

This award will support fundamental scientific research that will investigate how aluminum moves around a friction stir welding tool and how this movement influences the formation of sub-surface defects (voids). Due to its many advantages over other welding processes, friction stir welding has rapidly gained popularity in numerous manufacturing industries. However, certain limitations have slowed its mass implementation. This research seeks to address a lack of knowledge about two limitations in friction stir welding: (1) the need for costly post weld inspection of sub-surface defects in high-reliability applications (for example: defense and aerospace industries), and (2) the desire to increase processing speed to allow for high-volume production (for example: automotive industry). Faster welding speeds increase the likelihood of defect formation. A fundamental understanding of the precise mechanisms of material flow around the friction stir tool and its role in sub-surface defect formation is currently lacking. This research will generate the knowledge necessary to help U.S. manufacturers predict defect formation, hence allow them to design a friction stir welding process that produces defect-free welds. Addressing the aforementioned limitations will greatly expedite the mass implementation of this joining method, which will have a positive impact on U.S. manufacturing, the U.S. economy, and National Security. The award will also facilitate training of the future workforce as students across all levels will gain exposure to and experience in advanced joining technologies. Knowledge generated from this project will be distributed publicly through conference presentations, journal articles, industry tours, and open house engineering expositions.The goal of this research is to generate a fundamental understanding of the physics behind the intermittent movement (an extrusion-like process) of metal around the friction stir tool once per tool revolution. This phenomenon has been widely reported in the manufacturing engineering community by means of force measurements and by studying weld cross-sections after completing the weld. However, an understanding of why this intermittent material movement occurs and direct in-process observations do not exist. One leading hypothesis is that a cavity opens up in the wake of the advancing tool and that material is subsequently extruded into this cavity during each rotation of the tool. In a good welding condition, this cavity is completely filled. However, when there is a breakdown in the material flow, the cavity is not filled completely and a defect (void) remains. This hypothesis will be tested by means of novel, in-process proton radiography of the friction stir welding process of an aluminum alloy. Proton radiography at the Los Alamos Neutron Science Center provides the capability of producing a series of radiographic images (like x-rays) of the weld zone that will show whether or not a cavity is forming and filling. The knowledge gained through this physical experimentation, combined with other experiments conducted at the University of Madison-Wisconsin, will drive the numerical simulation of the intermittent flow phenomenon. Simulation of this phenomenon is largely absent from the published literature. In this work, the complex material flow and cavity formation and filing processes will be modeled and simulated using advanced Lagrangian based numerical techniques. Ultimately, this will provide the means to predict defect formation, and design measures to avoid it during production.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该奖项将支持基础科学研究，研究铝如何在搅拌摩擦焊接工具周围移动以及这种移动如何影响次表面缺陷（空隙）的形成。由于与其他焊接工艺相比具有许多优点，搅拌摩擦焊已在众多制造业中迅速普及。然而，某些限制减缓了其大规模实施。本研究旨在解决对搅拌摩擦焊的两个局限性缺乏了解的问题：(1) 在高可靠性应用（例如：国防和航空航天工业）中需要对次表面缺陷进行昂贵的焊后检查，以及（2）希望提高处理速度以实现大批量生产（例如：汽车工业）。更快的焊接速度会增加缺陷形成的可能性。目前缺乏对搅拌摩擦工具周围材料流动的精确机制及其在次表面缺陷形成中的作用的基本了解。这项研究将产生必要的知识，帮助美国制造商预测缺陷的形成，从而使他们能够设计出产生无缺陷焊缝的搅拌摩擦焊工艺。解决上述限制将大大加快这种加入方式的大规模实施，这将对美国制造业、美国经济和国家安全产生积极影响。该奖项还将促进未来劳动力的培训，因为各个级别的学生都将接触先进的连接技术并获得经验。该项目产生的知识将通过会议演讲、期刊文章、行业参观和开放日工程博览会公开传播。这项研究的目标是对每次工具旋转一次搅拌摩擦工具周围金属间歇运动（类似挤压的过程）背后的物理原理有一个基本的了解。通过力测量和完成焊接后研究焊接横截面，这种现象已在制造工程界得到广泛报道。然而，对于为什么会发生这种间歇性物质运动的理解以及直接的过程中观察并不存在。一个主要的假设是，在工具前进后会出现一个空腔，并且在工具每次旋转期间材料随后被挤出到该空腔中。在良好的焊接条件下，该空腔被完全填充。然而，当材料流发生故障时，型腔不会完全填充，并且会留下缺陷（空隙）。这一假设将通过铝合金搅拌摩擦焊接过程的新型过程中质子射线照相技术进行检验。洛斯阿拉莫斯中子科学中心的质子射线照相技术能够生成焊接区域的一系列射线照相图像（如 X 射线），以显示空腔是否正在形成和填充。通过该物理实验获得的知识，与威斯康星州麦迪逊大学进行的其他实验相结合，将推动间歇流现象的数值模拟。已发表的文献中基本上没有对这种现象的模拟。在这项工作中，将使用先进的基于拉格朗日的数值技术对复杂的材料流动、空腔形成和填充过程进行建模和模拟。最终，这将提供预测缺陷形成的方法，并设计在生产过程中避免缺陷形成的措施。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Influence of Tool Runout on Force Measurement During Internal Void Monitoring for Friction Stir Welding of 6061-T6 Aluminum

• DOI: 10.1115/1.4051009
• 发表时间: 2021-04
• 期刊: Volume 2: Manufacturing Processes; Manufacturing Systems; Nano/Micro/Meso Manufacturing; Quality and Reliability
• 作者: D. Franke;M. Zinn;S. Rudraraju;F. Pfefferkorn

Novel Correlations Between Process Forces and Void Morphology for Effective Detection and Minimization of Voids During Friction Stir Welding

工艺力与空洞形态之间的新关联，可有效检测搅拌摩擦焊过程中的空洞并将其最小化

• DOI: 10.1115/1.4054338
• 发表时间: 2022
• 期刊: Journal of Manufacturing Science and Engineering
• 作者: Ansari, Mohammad Ali;Agiwal, Hemant;Zinn, Mike;Pfefferkorn, Frank;Rudraraju, Shiva
• 通讯作者: Rudraraju, Shiva

Numerical Investigation Into the Influence of Alloy Type and Thermo-Mechanics on Void Formation in Friction Stir Welding of Aluminum Alloys

合金类型和热力学对铝合金搅拌摩擦焊空洞形成影响的数值研究

• DOI: 10.1115/1.4062270
• 发表时间: 2023
• 期刊: Journal of Manufacturing Science and Engineering
• 作者: Ansari, Mohammad Ali;Agiwal, Hemant;Franke, Daniel;Zinn, Michael;Pfefferkorn, Frank E.;Rudraraju, Shiva
• 通讯作者: Rudraraju, Shiva

Understanding process force transients with application towards defect detection during friction stir welding of aluminum alloys

• DOI: 10.1016/j.jmapro.2020.03.003
• 发表时间: 2020-06-01
• 期刊: JOURNAL OF MANUFACTURING PROCESSES
• 影响因子: 6.2
• 作者: Franke, Daniel;Rudraraju, Shiva;Pfefferkorn, Frank E.
• 通讯作者: Pfefferkorn, Frank E.

Material flow visualization during friction stir welding using high-speed X-ray imaging

使用高速 X 射线成像实现摩擦搅拌焊接过程中的材料流可视化

• DOI: 10.1016/j.mfglet.2022.08.016
• 发表时间: 2022
• 期刊: Manufacturing Letters
• 影响因子: 3.9
• 作者: Agiwal, Hemant;Ali Ansari, Mohammad;Franke, Daniel;Faue, Patrick;Clark, Samuel J.;Fezzaa, Kamel;Rudraraju, Shiva;Zinn, Michael;Pfefferkorn, Frank E.
• 通讯作者: Pfefferkorn, Frank E.