Ultrasonic Additive Manufacturing of Multi-Material Structures

超声波添加剂制造是一种从铝箔原料制造全致密金属结构的固态添加剂工艺。当与减法工艺相结合时，它可用于制造包含不同金属(例如铝、铜和钛)、用于冷却和其他运输目的的内部保形通道以及传感器、增强纤维、电子电路、光纤和智能材料等温度敏感元件的3D结构。目前，由于缺乏对该过程及其如何影响建筑性能的科学了解，限制了建筑的质量和大小，以及可以添加焊接的不同材料组合的范围。该奖项支持基础研究，以便了解其复杂的工艺-性能关系，并使用商业设备中已有的硬件实现现场工艺质量监控。这项研究的结果将导致这种基于美国的制造技术在汽车、航空航天、生物医学和电子行业中的更多使用。研究目的是将宏观能量传递效应(即焊机中的机电传递、超声波电极在箔上传递的振动能量、机械柔度对可用于动态再结晶微观组织的能量的影响)与焊接界面处的微观组织和超声波添加剂制造的机械性能的细节相关联。将建立第一性原理热力学模型，以描述超声波添加剂制造过程中的完整能量流动，包括焊机中的系统级机电关系(使用经典电声学理论)和可用于再结晶微结构的能量的量化(根据输入焊接能量、表面和体积能量以及损耗之间的热力学平衡)。现场测量声电极剪切力的实验技术将与焊接振动幅度、电压和电流的测量相结合，以验证能量模型。这些经过验证的模型将用于预测新材料组合(如超高强度钢和钛)中的过程-性能关系，实现新的3D焊接配置，在不进行大规模实验试验的情况下优化过程参数，并为克服当前质量、尺寸和实时过程监控限制的新的基于功率的过程控制框架提供基础。智能优点的一个关键方面是，这将是第一次全面的超声波添加剂制造过程的能量图，也是第一次通过现场焊接功率测量和微观结构分析进行实验验证。

Ultrasonic additive manufacturing is a solid-state additive process for fabrication of fully-dense metal structures from foil stock. When combined with subtractive processes, it can be used to fabricate 3D structures that incorporate dissimilar metals (e.g., aluminum, copper, and titanium), internal conformal channels for cooling and other transport purposes, and temperature-sensitive components such as sensors, reinforcement fibers, electronic circuits, fiber optics, and smart materials. A lack of scientific understanding of the process and how it affects build properties currently limits the quality and size of builds and the range of dissimilar material combinations that can be additively welded. This award supports fundamental research in order to understand its complex process-property relationships and enable in-situ process quality monitoring using hardware that already exists in commercial equipment. Results from this research will lead to increased use of this US-based manufacturing technology in the automotive, aerospace, biomedical, and electronics industries. The research objective is to correlate macroscopic energy transfer effects (i.e., electromechanical transduction in the welder, vibrational energy imparted by sonotrode on foil, and effects of mechanical compliance on the energy available to dynamically recrystallize the microstructure) with details of the microstructure at the weld interface and mechanical properties of ultrasonic additive manufacturing builds. First-principles thermodynamic models will be formulated to describe the complete flow of energy in the ultrasonic additive manufacturing process, including system level electromechanical relationships in the welder (using classical electroacoustics theory) and quantification of the energy available to recrystallize the microstructure (from thermodynamic balances between input weld energy, surface and bulk energies, and losses). In-situ experimental techniques for measuring shear force at the sonotrode will be integrated with measurements of weld vibration amplitude, voltage, and current to validate the energy models. These validated models will be used to predict process-property relationships in new material combinations (e.g., ultra high strength steels and titanium), enable new 3D weld configurations, optimize process parameters without massive experimental trials, and provide the basis for a new power-based process control framework that overcomes current quality, size, and real-time process monitoring limitations. A key aspect of intellectual merit is that this will be the first comprehensive energy mapping of the ultrasonic additive manufacturing process and also the first to be experimentally verified by both in-situ weld power measurements and microstructural analyses.