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

講座人：Andreas Mandelis 教授

講座時間：11月28日14:00

地點(diǎn)：南校區(qū)圖書館4樓報(bào)告廳

講座人介紹：

Andreas Mandelis，博士，多倫多大學(xué)教授，加拿大首席科學(xué)家（Canada Research Chair, TierI）。1977 年畢業(yè)于普林斯頓大學(xué)，獲機(jī)械與航空工程/應(yīng)用物理與材料科學(xué)雙重碩士學(xué)位，1979 年于同一學(xué)校獲得應(yīng)用物理與材料科學(xué)博士學(xué)位。Mandelis 教授為多倫多大學(xué)機(jī)械與工業(yè)工程系（MIE）、電子與計(jì)算機(jī)工程系（ECE）雙聘教授，是 MIE先進(jìn)擴(kuò)散波與光聲技術(shù)實(shí)驗(yàn)中心（CADIPT）主任。2004 年在波鴻魯爾大學(xué)獲洪堡學(xué)者，2007 年獲得安大略省科學(xué)技術(shù)探索基金（Ontario Premier’s Discovery Award），2008 年評為加拿大首席科學(xué)家，2013 年于慕尼黑工業(yè)大學(xué)獲重邀洪堡學(xué)者獎勵，2017 年為約克大學(xué)兼職教授。Mandelis 教授也是美國物理學(xué)會（APS）、美國機(jī)械工程師學(xué)會（ASME）、加拿大物理學(xué)會（CAP）、國際電氣與電子工程協(xié)會（IEEE）以及光學(xué)儀器工程師協(xié)會（SPIE） Fellow。Mandelis 教授在光聲光熱技術(shù)領(lǐng)域具有國際廣泛認(rèn)知度，發(fā)表論文 600 余篇，授權(quán)專利 60 余項(xiàng)，論文被引用量達(dá) 90524 次（截止 2023 年 5 月），引用率 h 指數(shù) 98（發(fā)表 h 篇論文被引用 h 次時的最大 h 值）。主要研究方向包括：熱物理與熱擴(kuò)散波測量技術(shù)、半導(dǎo)體材料缺陷的擴(kuò)散波表征技術(shù)、光熱輻射深度表征測量、光聲工業(yè)無損檢測與氣體測量、生物傳感器與光聲醫(yī)學(xué)檢測技術(shù)等。

講座內(nèi)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.

主辦單位：光電工程學(xué)院