基于声悬浮的非透明材料内部微结构超声聚焦加工方法研究

With the rising of inner processing technology of micro internal structure in transparent materials (such as polymer dielectric material PMMA) by femtosecond laser and the application of high intensity focused ultrasound (HIFU) to eroding organisms target material, a new technology of directly manufacturing internal structure in the material, referred to as "inner processing" technology, has been rapidly developing. But the directly processing technology of inner micro structure in non transparent material such as metal has not yet been put forward. A new technology scheme of the metal inner processing technology using ultrasonic suspension, acoustic array focusing etc was proposed in this project. The solid-liquid metal material under temperature control is suspended in the standing wave node by ultrasonic levitation technique, and the phased array is dynamically focused on the inside of the blank, there are pitting to form a structure. Focusing performance and temperature control in this technology play an important role in this advanced technical system. Aiming at solving the lower focusing performance technical problem of the existing phased array ultrasonic array, the theory of acoustic soliton was introduced in this project. Study on the propagation law of acoustic solitons in time varying and temperature varying structure, on the mechanism of attraction and agglomeration effect of acoustic solitons by ultrasonic standing wave trap will being conducted. The nonlinear coherent interaction condition and formation law of acoustic soliton in potential well will be revealed. Results will lead to the greater improving of the machining ability and positioning accuracy of the focused point. The theory and method of ultrasonic focusing in the microstructure of metallic and other non transparent materials then be roughly explored. Fabrication of three dimensional hollow microstructures in non transparent materials of metal alloy will be realized. The existing inner processing technology system will be further enriched.

随着飞秒激光聚焦透明材料内部点蚀加工成形技术兴起，材料内部微结构封闭式加工方法（简称“内加工”）应运而生。而非透明材料例如黑色系金属合金内部微结构内加工方法尚未提出。项目提出黑色系金属合金中内部微结构内加工方法新方案。首先，应用超声悬浮技术，将处于固-液临界相变状态金属合金坯料悬浮于超声驻波节点位置；然后，应用相控超声阵列动态聚焦技术将超声阵列依次聚焦于悬浮坯料内部并点蚀加工成形。方案中，超声聚焦作用关键，引入激光超声技术、声孤立子理论研究建立超声非线性聚焦理论和方法。首先，研究高温表面激光激发声孤立子条件；然后，研究声孤立子在坯料内部时变温变结构中传播规；研究超声驻波势阱焦域中对声孤立子吸引、纠缠与相干机制；研究非线性作用聚变聚焦点蚀加工机理；最后，通过试验研究和数值分析手段，验证非透明黑色系金属合金坯料内部微结构超声聚焦加工理论和方法，并努力探索不同基体材料-构件封闭空间内加工成形方法

材料加工有内加工方法与外加工方法，而内加工方法是新兴的学术研究前沿。激光内加工方法可用于透明材料加工，例如制造光子晶体。本项目研究非透明材料金属、硅材料等超声内加工，创新地建立了基于微重力场、声孤子的液态金属内腔可控加工理论方法。.项目开展激光脉冲作用于金属表面激发超声孤子的理论研究。建立了非Fourier温度场表达式，给出热传导系数跳跃位置理论计算公式；建立了初值间断Riemann问题的KdV-Burgers方程，给出声孤子理论计算公式与非线性传播特性；阐明了激光脉冲与金属液滴作用激发声孤子的发生机理与理论条件，研究成果在物理学报发表；.项目开展声孤子在金属内部传播特性与聚焦方法研究。应用一维金属颗粒链模型、非线性LC传输线电路，给出了单孤子传播速度与峰值、脉宽、声阻抗之间的关系；研究了多孤子碰撞、附加缺陷的相移特性，建立了基于温度梯度、时延可控的多孤子“Y”形输入聚合聚焦加工方法，研究成果在Micromachines发表；.项目开展超声复合场内加工镓铟合金内腔的试验研究。创新建立金属液滴超声驻波悬浮与孤子局域空化复合运动数学模型，试验与仿真结果表明：镓铟合金声空化与声悬浮之间存在内腔加工的有效工作区间；内腔尺度与声孤子包络频率、峰值、空化核初始半径有关，复合声场频率比与相位差有效控制内腔尺度与定位精度；试验成功实现镓铟合金150μm内腔的0.90s时间内声空化制造与声悬浮保形，方案可行。研究成果申请国际发明专利，其它关键技术研究成果发表在TOP期刊International--Journal of pharmaceutics。.金属内加工方法除了加工微腔，还将改变未来智能结构设计方法，例如，可在金属液滴内部输入压电材料制造异质单元结构阵列，构造感知-承载一体化智能结构如智能轴承球，从而直接通过滚动球感知轴承内部运动状态信息。