GOALI/Collaborative Research: Improving Incremental Sheet Forming by Ultrasonically Enhanced Material Deformation

该学术联络机会奖（GOALI）支持有助于理解超声增强增量板成形的研究，资金来自民用、机械和制造创新部门的先进制造计划以及材料研究部门的金属和金属纳米结构计划。尽管超高强度材料发展迅速，但其使用的准备程度受到相关制造工艺的限制，特别是在钣金成形领域。一种有希望的解决方案是在成形过程中暂时软化材料，这可以在超声波能量的帮助下实现。然而，这种软化现象的基本原理仍然难以捉摸。应用超声波能量的另一个好处是改善了摩擦学性能。在成形技术中，增量板料成形以其工具的通用性和较高的灵活性在快速成形方面具有优势，满足了日益激烈的产品更新和定制化的市场需求。然而，实现高几何精度和表面光洁度是具有挑战性的。在这方面，超声软化和改性摩擦都可以作为一种独特的工艺和性能增强方案。超声波对材料性能影响的基础研究有助于将超声波能量有效地结合到板材的增量成形中，这极大地促进了板材在航空航天、汽车和生物医学等行业的应用。参与该项目的学生将获得材料、机械工程和制造领域的多学科知识和研究经验。学生，特别是女性和少数族裔，有机会与GOALI合作伙伴波音工程师互动。本项目旨在推进超声软化机制对材料变形行为的基础知识。该研究旨在有效利用超声能量来改善增量成形过程，同时改善其表面摩擦学行为。首先，研制了一种新型超声辅助微拉伸试验台，该试验台配备了原位高速光学显微镜成像系统。这使得超声振动周期内瞬态晶间应变场和晶内应变场的数字图像相关分析成为可能。然后进行死后多尺度微观结构表征。建立了基于位错密度的晶体塑性本构材料模型，揭示了超出实验观察的物理原理。其次，对UA-ISF工艺进行了全面研究，建立了减小成形力、提高成形精度、改善表面光洁度与ISF和超声参数之间的关系。最后，结合第一项研究中建立的超声影响材料本构模型，建立了UA-ISF的声力耦合过程模型。通过实验验证，该模型可用于复杂自由几何形状零件成形中的UA-ISF优化。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。

This Grant Opportunity for Academic Liaison with Industry (GOALI) award supports research that contributes to the understanding of ultrasonically-enhanced incremental sheet forming with funding from the Advanced Manufacturing Program in the Civil, Mechanical, and Manufacturing Innovation Division and from the Metals and Metallic Nanostructures Program in the Division of Materials Research. Despite the rapid development of ultra-high strength materials, their readiness to use is limited by limitations in the associated manufacturing processes, especially in the field of sheet metal forming. One promising solution is to temporarily soften the material during the forming process, which can be achieved with the assistance of ultrasonic energy. However, the underlying principles of this softening phenomenon remain elusive. Another benefit of applying ultrasonic energy is improved tribological behavior. Among forming technologies, incremental sheet forming is advantageous in rapid prototyping based on its universal tooling and high flexibility, which meet the increasingly competitive market demands of product updates and customization. However, achieving high geometric accuracy and surface finish quality are challenging. In this aspect, both the ultrasonic softening and modified friction can be harnessed as a unique process and property enhancement solution. The fundamental research of ultrasonic effects on material behavior facilitates effective incorporation of ultrasonic energy into incremental sheet forming, which greatly benefits sheet metal applications in industries such as aerospace, automotive and biomedical. Students involved in the project gain multidisciplinary knowledge and research experiences in materials, mechanical engineering and manufacturing. Students, particularly women and underrepresented minorities, have the opportunity to interact with GOALI partner Boeing engineers.This project aims to advance the fundamental knowledge of ultrasonic softening mechanisms on material deformation behavior. The research is to effectively utilize ultrasonic energy to enhance the incremental sheet forming (ISF) process based on both its bulk softening and modified surface tribological behavior. First, an innovative ultrasonically assisted (UA) micro-tensile testbed, equipped with an in situ high speed optical microscope imaging system, is developed. This enables digital image correlation analysis on the transient inter and intragranular strain field within the ultrasonic vibration cycle. Post mortem multiscale microstructure characterizations are then performed. A dislocation density-based crystal plasticity constitutive material model is developed to reveal the physical principles that are beyond experimental observations. Second, the UA-ISF process is comprehensively studied, in which relationships between the reduced forming force, increased forming accuracy, improved surface finish and the ISF and ultrasonic parameters are established. Finally, a coupled acousto-mechanical process model for UA-ISF is developed, which incorporates the ultrasonically affected material constitutive model developed in the first task. With experimental validations, this model would be utilized to optimize UA-ISF in forming parts with 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.