希望之光大讲堂第八讲：Lock-in thermography of green powder metallurgy component flaws using preventive non-destructive imaging

讲座名称：Lock-in thermography of green powder metallurgy component flaws using preventive non-destructive imaging

讲座人：Andreas Mandelis 教授

讲座时间：11月28日14:00

地点：南校区图书馆4楼报告厅

讲座人介绍：

Andreas Mandelis，博士，多伦多大学教授，加拿大首席科学家（Canada Research Chair, TierI）。1977 年毕业于普林斯顿大学，获机械与航空工程/应用物理与材料科学双重硕士学位，1979 年于同一学校获得应用物理与材料科学博士学位。Mandelis 教授为多伦多大学机械与工业工程系（MIE）、电子与计算机工程系（ECE）双聘教授，是 MIE先进扩散波与光声技术实验中心（CADIPT）主任。2004 年在波鸿鲁尔大学获洪堡学者，2007 年获得安大略省科学技术探索基金（Ontario Premier’s Discovery Award），2008 年评为加拿大首席科学家，2013 年于慕尼黑工业大学获重邀洪堡学者奖励，2017 年为约克大学兼职教授。Mandelis 教授也是美国物理学会（APS）、美国机械工程师学会（ASME）、加拿大物理学会（CAP）、国际电气与电子工程协会（IEEE）以及光学仪器工程师协会（SPIE） Fellow。Mandelis 教授在光声光热技术领域具有国际广泛认知度，发表论文 600 余篇，授权专利 60 余项，论文被引用量达 90524 次（截止 2023 年 5 月），引用率 h 指数 98（发表 h 篇论文被引用 h 次时的最大 h 值）。主要研究方向包括：热物理与热扩散波测量技术、半导体材料缺陷的扩散波表征技术、光热辐射深度表征测量、光声工业无损检测与气体测量、生物传感器与光声医学检测技术等。

讲座内容：

Pre-sintered (“green”) compressed metal powder components were studied using Lock-In Thermography (LIT) to assess the capability of this methodology through non-destructive imaging to produce quantitative information on crucial material integrity properties used in automotive manufacturing that impact mechanical strength and integrity, such as density non-uniformity. Using pre-optimized experimental parameters, including infrared-camera phase stabilization by means of ultra-high sampling frequency rates, LIT was shown to reveal distinct phase shift bi-modalities and widespread non-uniformity in an industrial sample which exhibited surface cracks. In juxtaposition, LIT images from another sample without cracks were much more uniform across the entire sample. A regression fitting program was used to determine the local thermal diffusivity at critical phase-varying locations of the cracked sample and a positive correlation was found between the thermal diffusivity and the phase shift with a lone exception occurring at the exact location of the crack. Optical imaging of the sample also revealed a positive correlation between the phase shift and the local sample porosity which determines local density. The combination of these procedures led to the concept of preventive non-destructive evaluation (P-NDE) as an important new inspection approach which hinges on the premise of developing adequate analytical and measurement tools to investigate material integrity deficit factors during manufacturing that may lead to catastrophic flaws / cracks before the emergence of such flaws.

主办单位：光电工程学院