EAGER/Collaborative Research: Fundamentals of Acousto-Plasticity and Tribology in Ultrasonically Enhanced Incremental Sheet Forming

当今快速发展和竞争激烈的市场增加了产品更新的频率，并迅速扩大了对定制零件的需求。因此，高质量，低成本的原型和小批量制造工艺是可取的。目前还没有成熟的增材制造或快速原型制造方法来制造金属板或大型薄型零件——传统的增材制造制造空间太小，而且翘曲太大，无法生产汽车车身面板等零件。增量板成形（ISF）是一种利用小型工具在金属板上进行转换时引起局部变形的制造方法，由于其无模具设置，通用工具和高灵活性，是最近研究的一种制造方法。然而，目前ISF成形零件的尺寸和几何精度以及表面光洁度都是一个挑战，但主要缺点是该方法的可成形性有限，导致废品率非常高。超声波振动以其块状材料软化效果、表面改性和摩擦行为改善而闻名，为减轻这些担忧提供了希望。这项早期概念探索性研究（EAGER）奖支持基础研究，以推进超声对ISF过程中材料行为的影响。这项独特的多学科研究的成功将显著提高成形性和加工能力。利用这一新知识将扩大ISF在航空航天，汽车，国防和医疗等各个行业的应用，从而对美国国家安全和经济福利产生直接的积极影响。参与该项目的学生将获得包括材料、机械和制造科学与技术在内的多学科知识和研究能力。外联活动将强调对妇女和代表性不足的少数民族的指导。该项目的目标是通过在成形过程中有效地将超声波振动应用于工具，对增量板成形（ISF）工艺进行创新改进。潜在的好处是减小成形力，提高成形性，增加尺寸和几何公差，改善表面质量。该合作项目包括利用高速数字图像相关分析，在超声振动拉伸测试中对材料行为进行综合实验和建模研究。结果将有助于设计一种有效的方法，将超声波能量纳入ISF过程。超声辅助ISF将在不同条件下进行。本文将从过程变量、后处理性能和多尺度微观结构等方面研究超声振动与材料变形的相互作用机制。研究了超声振动对表面和体性能的影响，包括对织构和晶粒尺寸的影响。该项目的目标是(1)了解在超声波振动下控制材料行为的基本原理；(2)演示超声波辅助增量成形工艺对复杂自由几何形状的改进。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Today's fast-moving and competitive markets increase the frequency of product updates and rapidly expand demands for customized parts. Accordingly, high quality, low-cost prototyping and low volume manufacturing processes are desirable. No proven additive manufacturing or rapid prototyping approaches exist for sheet metals or large, thin parts - conventional additive manufacturing has too small of a build space and warps too much to produce parts such as automotive body panels. Incremental sheet forming (ISF), which utilizes a small tool to induce local deformation as it translates over the metal sheet, is a manufacturing approach that has been investigated recently because of its die-less setup, universal tooling and high flexibility. However, achieving dimensional and geometric accuracy as well as surface finish of the current ISF formed parts are a challenge, but the main drawback is the limited formability in the approach, leading to very high scrap rates. Ultrasonic vibration, known for its bulk material softening effects, surface modification and friction behavior improvements, offers promise in alleviating these concerns. This EArly-concept Grant for Exploratory Research (EAGER) award supports fundamental research to advance knowledge of the ultrasonic effects on material behavior in ISF processes. Success in this unique multidisciplinary study will lead to significant improved formability and process capabilities. Leveraging this new knowledge will expand ISF applications in various industries, such as aerospace, automotive, defense and medical, so that it has direct positive impact on the US national security and economic welfare. Students involved in the project will gain multidisciplinary knowledge and research capabilities including material, mechanical and manufacturing science and technologies. Outreach activities will emphasize the mentoring of women and underrepresented minorities. The objective of this project is an innovative improvement of the incremental sheet forming (ISF) process by effectively applying ultrasonic vibration to the tool during the forming operation. The potential benefits are to reduce forming force, increase formability, increase dimensional and geometrical tolerance and improve surface quality. This collaborative project includes an integrated experimental and modeling study of material behavior during tensile testing with ultrasonic vibration utilizing high speed digital image correlation analysis. The results will serve to design an effective approach for incorporating ultrasonic energy into ISF process. Ultrasonically assisted ISF will then be performed under different conditions. The interaction mechanisms between ultrasonic vibration and material deformation during ISF will be studied in terms of in-process variables, post-processing properties and multi-scale microstructure. The effect of ultrasonic vibration on both surface and bulk properties will be studied, including the impact on texture and grain size. The goals of this project are (1) understanding of the fundamental principles that govern the material behavior under ultrasonic vibration and (2) demonstration of the improvements enabled by ultrasonically assisted incremental forming process for complex free form geometries.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.