美國新奧爾良大學David Hui教授做客第269期化苑講壇
報告題目：Composites under Harsh Environments: Civil Engineering and Aerospace Engineering perspectives
報 告 人 ：David Hui教授
報告時間：2017年6月6日（周二）下午14:30
報告地點：化學樓二樓一號會議室
邀 請 人 ：解孝林教授
報告人簡介：
Dr. David Hui is Professor of Mechanical Engineering and director of Composites Materials Research Laboratory at University of New Orleans. Dr. Hui has edited over 40 widely cited books. He has served as founder and editor-in-chief of one of the most prestigious journals in composite materials, Composites B Engineering journal. Dr. Hui has conducted approx. 4 million US dollar funded research on composites materials and nano-materials, mostly for mechanical/aerospace engineering and ship structures applications. Dr. Hui has co-authored over 220 SCI journal publications, and these papers have received over 3000 citations from ISI web of science
報告內容：
The work presents an overview of the current state of the art in low temperature effects on materials in terms of durability and safety of vehicles. Susceptibility of composites to failure at low temperature is a critical issue for the aerospace industry. Spacecrafts operate at temperatures well below -200 degC. High altitudes aircrafts routinely fly at -70 deg C to -100 degC. These low temperatures result in two competing effects on composite stiffness. One beneficial effect involves increased stiffness because the polymer matrix would harden at low temperature. The other detrimental effect involves increased thermally-induced stress, which produces microcracks in matrix, which in turn, reduces the overall stiffness of the composites. These two competing beneficial-detrimental phenomena at the microstructure level have been studied for decades, but a quantitative understanding of the interplay of these two effects has continued to elude the researchers. Additional complexities arise when the stiffness increase effect is considered because of high strain rate loading. Long term exposure to cyclic or vibration can again reduce the stiffness. The competing effects for fatigue of fiber-reinforced polymer composites at low temperatures will be presented. Emphasis will be on civil engineering structural and other involving earthquake applications, orthogrids, FRP rebars, sandwich structures, guardrails, piers and structural members.
