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

这个学术联络与工业（GOALI）奖资助机会支持研究，有助于理解超声波增强的增量板材成形，由土木，机械和制造创新部门的先进制造计划和材料研究部门的金属和金属纳米结构计划提供资金。尽管超高强度材料发展迅速，但它们的使用受到相关制造工艺的限制，特别是在金属板成形领域。一个有前途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。应用超声能量的另一个好处是改善摩擦学行为。在成形技术中，板料渐进成形技术以其通用的模具和高柔性的特点在快速成形中具有优势，满足了日益激烈的市场对产品更新和定制的需求。然而，实现高几何精度和表面光洁度质量具有挑战性。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解决方案。超声波对材料行为影响的基础研究有助于将超声波能量有效地结合到渐进板料成形中，这极大地有利于航空航天、汽车和生物医学等行业的金属板料应用。参与该项目的学生获得材料，机械工程和制造方面的多学科知识和研究经验。学生，特别是女性和少数民族，有机会与GOALI合作伙伴波音公司的工程师进行互动。该项目旨在推进材料变形行为的超声软化机制的基础知识。 基于材料的体积软化和表面摩擦学特性的改善，有效地利用超声波能量强化板料渐进成形过程。首先，开发了一种创新的超声辅助（UA）微拉伸试验台，配备了原位高速光学显微镜成像系统。这使得在超声振动周期内的瞬态晶间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。建立了一个基于位错密度的晶体塑性本构模型，揭示了实验所不能揭示的物理规律。其次，对UA-ISF工艺进行了全面的研究，建立了ISF和超声参数与成形力降低、成形精度提高和表面光洁度改善之间的关系。最后，一个耦合的声-力过程模型的UA-ISF开发，其中包括超声影响的材料本构模型中开发的第一个任务。通过实验验证，该模型将用于优化UA-ISF，以形成具有复杂自由形状几何形状的零件。该奖项反映了NSF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.