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

材料，特别是金属，在暴露于高频弹性波时更容易变形。这种现象被称为声塑性，并且已经用于若干应用中，例如金属成形、挤出、焊接、倒装芯片接合和超声增材制造。尽管其被广泛使用，但由于缺乏对基本机制的明确理解，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。学生招聘，包括夏季本科研究机会，将集中在代表性不足的少数民族。此外，动手计算和实验工作坊将针对K-12学校的儿童和教师。金属声塑性背后的机制尚未完全理解，因为：（1）声激发发生在宏观尺度上，但其影响可以在时空尺度上传播几个数量级;（2）单尺度模型模糊了分布在多个尺度上的机制，并且不能解决全部复杂性;以及（3）由于事件的快速时间尺度，探测声影响的位错塑性是具有挑战性的。这项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。超声振动下的塑性变形的复杂动力学将通过并发原子连续模拟的特点。原位时间分辨实验将用于捕获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的多尺度声塑性的理解。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.