報告題目：Microbridge Tests
報告人：Prof. Tongyi Zhang (張統一)
報告時間：
報告地點：浙江大學玉泉校區教12-118
報告摘要：
In the present work, we summarize the novel microbridge testing method for mechanical characterization of thin films including single-layer, bilayer, trilayer, and multilayer thin films. The samples for microbridge tests were prepared with the microelectromechanical fabrication technique such that they were easy to be handled with. The microbridge tests were conducted with a load and displacement sensing nanoindenter system equipped with a microwedge probe. The length of the microwedge probe is larger than the width of microbridge samples, which makes one-dimensional analysis appropriate. In mechanics analysis, we modeled the substrate deformation with three coupled springs and considered residual stress in each layer, thereby resulting in a closed-form formula of deflection versus load. The microbridge testing method allows us to simultaneously evaluate the Young’s modulus, residual stress and bending fracture strength of single-layer films from an experimental load-deflection curve. The mechanics analysis shows that four parameters, bending stiffness, tensile stiffness, residual resultant force and residual moment, determine the bending behavior of a multilayer beam including the initial deflection caused only by residual moment and residual resultant force without any applied loads. An experimental procedure was developed to determine the four parameters. In addition to the characterization of elastic behaviors of thin films, the microbridge test has been extended to investigate the plastic behavior of thin films. Examples to demonstrate the developed microbridge test will be illustrated on single-layer, bilayer and trilayer films. The microbridge test is further developed to the nanobridge test, in which the adhesion between the probe and a tested nanowire must be considered.
報告人簡介：
張統一教授是我國自己培養、在香港科技大學成長的學者。他于1982年和1985年在北京科技大學材料物理專業獲碩士和博士學位。畢業后獲得德國洪堡基金會獎學金，1986—1988年在德國哥廷根大學任研究員。1988—1990年在美國羅徹斯特大學進行博士后研究。1990—1993年在美國耶魯大學任副研究員。1993年到香港科技大學任教至今，目前是該校講座教授。研究領域包括鐵電與壓電材料的多場斷裂力學、微納觀力學和氫滲透與氫致開裂。他是2007年度國家自然科學二等獎第一獲獎人（共四位獲獎人）和1987年度自然科學二等獎第三獲獎人（共十位獲獎人）。2003年獲香港裘槎高級研究學者獎，2001年獲美國ASM International Fellow Award，1988年獲中國科學技術協會青年科技獎。他發表139篇SCI學術論文。5次收到Web of Science賀卡，祝賀他的“文章引用率在所從事領域位于1％前列，工作在領域里有重大的影響力”。截至2009年3月30日，他的論文SCI他引次數為1776次；其中在香港科技大學完成的4篇學術論文SCI他引次數為234、169、119和117次。獲得2項美國專利。在國際和國內學術會議上作特邀、主題和大會報告32次，并將在第12屆國際斷裂大會上作大會報告。組織和參與組織包括第八屆國際斷裂基礎大會在內的3次國際會議。為國際和國內學報編輯了八期特刊。
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