Collaborative Research: Understanding Acoustoplasticity through Multiscale Computational and In-Situ, Time-Resolved Experimental Approach

材料，尤其是金属，在高频弹性波的作用下更容易变形。这种现象被称为声塑性，已被应用于金属成形、挤压、焊接、倒装芯片键合和超声波增材制造等领域。尽管它被广泛使用，但由于缺乏对潜在机制的清晰理解，这些过程仍处于“试错”阶段。该奖项支持基础研究，通过计算和实验相结合的方法，从原子尺度到微观结构尺度，揭示驱动声塑性的变形过程。从该奖项中获得的知识可以改进振动/超声辅助制造方法，特别是超声增材制造，它具有按需、空间制造的潜力。该奖项将支持力学、高性能计算、数据科学、材料表征和测试之间的交叉研究。招生，包括夏季本科生研究机会，将重点关注未被充分代表的少数民族。此外，动手计算和实验研讨会将针对K-12学校的儿童和教师。金属声塑性背后的机制尚不完全清楚，因为：(1)声激励发生在宏观尺度上，但其影响可以在时空尺度上传播多个数量级；(2)单尺度模型掩盖了分布在多个尺度上的机制，不能完全解决复杂性问题；(3)由于事件的时间尺度快，探测声影响的位错塑性具有挑战性。本研究将通过结合多尺度模拟、时间分辨非线性波和显微镜来填补这些知识空白。通过同步原子连续体模拟来表征超声振动下塑性变形的复杂动力学。原位，时间分辨实验将用于捕捉超声振动下的微观结构演变，例如，使用扫描电子显微镜和电子背散射衍射。最后，一个基于机制的参数将被校准，以跨越多个时空尺度的模拟和实验，以实现对声塑性的多尺度理解。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。

Materials, especially metals, can be deformed more easily when exposed to high frequency elastic waves. Such phenomenon is called acoustoplasticity and has been used in several applications, such as metal forming, extrusion, welding, flip-chip bonding, and ultrasonic additive manufacturing. Despite its widespread use, these processes are still at a “trial and error” stage due to the lack of a clear understanding of the underlying mechanisms. This award supports fundamental research to unravel the deformation processes that drive acoustoplasticity through a combined computational and experimental approach, from the atomistic up to the microstructural scale. The knowledge gained from this award can improve vibration/ultrasonic assisted manufacturing methods, especially ultrasonic additive manufacturing, which has the potential for on-demand, in-space manufacturing. This award will support cross-cutting research between mechanics, high performance computing, data science, material characterization, and testing. Student recruitment, including for summer undergraduate research opportunities, will focus on underrepresented minorities. Additionally, hands-on computational and experimental workshops will target K-12 school children and teachers.The mechanisms behind acoustoplasticity in metals are not fully understood because: (1) acoustic excitation occurs in the macroscale, but its effects can be spread over orders of magnitude in the spatio-temporal scale; (2) single-scale models smear out the mechanisms spread over multiple scales and cannot address the full complexity; and (3) probing the acoustic-affected dislocation plasticity is challenging due to the fast time scale of the events. This research will fill these knowledge gaps by combining multiscale simulations, time resolved nonlinear waves, and microscopy. The complex dynamics of plastic deformation under ultrasonic vibrations will be characterized through concurrent atomistic-continuum simulations. The in-situ, time-resolved experiments will be used to capture the microstructural evolution under ultrasonic vibrations, e.g., with the use of scanning electron microscopy and electron back scatter diffraction. Finally, a mechanism-based parameter will be calibrated to bridge the simulations and experiments across multiple spatio-temporal scales for a multiscale understanding of acoustoplasticity.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.