增材制造点阵结构的超声共振谱性能表征

为了实现增材制造的点阵构件性能的可靠、快捷评判，优选超声共振谱技术进行检测方法研究. 使用增材制造工艺，制作了一系列Ti-6Al-4V的点阵结构试样，结构内含有不同宽度的平面型缺陷. 基于自建的超声共振谱检测系统开展试验，利用纵波超声换能器作为振动的激励源与接收传感器. 对共振频率与振动模态进行甄别，选取可靠的共振频率组合作为评判指标，构建马氏空间，按马氏距离对缺陷进行定量分析. 试验结果表明，虽然点阵试样结构复杂，但仍可以测得清晰明显的共振频率峰，且测量结果重现性好. 结果分析表明，点阵试样的共振频率峰位置与缺陷尺寸大小有强相关性，采用马氏距离可以实现缺陷的定量评价. 研究表明，超声共振谱技术为增材制造的复杂点阵构件的性能表征提供了较好的无损检测（NDT）解决方案.

Resonant ultrasound spectroscopy evaluation of additively manufactured lattice structure

Resonant ultrasound spectroscopy (RUS) was optimistically selected to study feasibility and implementation details of the testing method, in order to accomplish reliable and quick evaluation of the lattice components additively manufactured. A series of lattice structures of Ti-6Al-4V which contains planar defects of different widths was manufactured by additive manufacturing process. Experiments were carried out based on a home-made RUS system, and longitudinal ultrasonic transducers were used as the transmitter and receiver. The resonant frequencies and vibration modes were identified by setting suitable experimental parameters, and then a reliable combination of resonant frequencies was chosen to evaluate the defects by constructing a Mahalanobis space. Finally, the Mahalanobis distance was calculated for each specimen and defects were analyzed quantitatively. Experimental results show that resonant frequency peaks can be detected obviously and repeatedly even for the lattice components with complex structures. Results show that there is a strong correlation between positions of certain resonant frequency peak and the size of defect. Comparing with traditional non-destruction testing (NDT) method, RUS provides a favorable NDT solution for the lattice structure additively manufactured.