Damage detection in load-bearing additive manufacturing components through use of high-frequency ultrasonic waves

承载构件的损伤检测和健康监测一直是设计人员和制造商关注的主要问题。用于制造金属和非金属部件的现代工艺之一是增材制造（AM），也称为三维打印或快速原型制造。在增材制造过程中，计算机程序引导扫描仪将材料精确地存款在期望的点处，以逐层构建最终产品。这使得可以相对容易地以可承受的成本生产具有复杂几何形状的物体。该材料可以是金属、塑料或陶瓷，其通过能量源例如激光束、电弧、电子束或超声波熔化。AM组件中没有缺陷是至关重要的，特别是如果作为假体植入人体。对于假体，如膝关节，产品必须无缺陷。检测和监测在重复载荷下增长的缺陷需要采用先进的无损检测（NDT）技术，该技术不会损害产品的适用性。在本项目中，将采用一种独特的相控阵超声检测（PAUT）方法。PAUT已在最大10 MHz的有限频率的行业中使用多年。该频率水平不足以确保检测承载AM产品中的非常小的缺陷/裂纹。本研究提供了使用相控阵超声波检测方法与更高的频率，高达50 MHz，检测和监测AM制造的假体组件在重复负载。该方法能够在加载的早期阶段进行几微米的缺陷检测和破裂，解决了其他NDT技术的缺点。该项目完成后的成果是安全地制造增材组件，最大限度地减少制造部件的损坏，并促进无风险和可靠的生物医学产品，包括膝关节假体。瑞尔森大学和富士视觉声波公司之间的相互合作也是值得期待的。通过这个NSERC参与提案在更长的时间内扩展。

Damage detection and health monitoring of load-bearing components have been always prime concern for designers and manufacturers. One of modern processes used for manufacturing of metallic and non-metallic parts is additive manufacturing (AM), also referred to as three-dimensional printing or rapid prototyping. In an additive manufacturing process, a computer program directs a scanner to deposit the material precisely at desired spots to build up the final product layer by layer. This makes it possible to produce objects with complex geometries relatively easier and at an affordable cost. The material could be metal, plastic or ceramic which is melted by an energy source such as laser beam, arc, electron beam or ultrasound. The absence of defects in AM components is critically important, particularly if implanted in human body as a prosthesis. For prostheses, such as knee joint, the product must be defect-free. The detection and monitoring of defects growing under repeated loads necessitates to employ advanced non-destructive testing (NDT) techniques, which do not damage the serviceability of the product. In this project, a unique phased array ultrasonic testing (PAUT) method will be employed. The PAUT has been in use for several years by industries with limited frequency of maximum 10 MHz. This level of frequency is not high enough to assure detection of very small defects/cracks in load-bearing AM products. The present study offers the use of phased array ultrasonic testing method with higher frequencies, as high as 50 MHz, to detect and monitor AM manufactured prostheses components under repeated loads. The method enables defect detection and cracking of few microns over early stages of loading addressing shortcomings of other NDT techniques. The outcome of this project upon completion is to safely manufacture additive components, to minimize damage in the manufactured parts, and to promote risk-free and reliable biomedical products including knee joint prosthesis in service. It is also expected that the mutual collaboration between Ryerson University and FUJIFILM VisualSonics Inc. expands over longer terms through this NSERC engage proposal.