美国Ohio State University理论与应用力学实验室主任Herman Shen教授讲座二：THE OHIO STATE UNIVERSITY COLLEGE OF ENGINEERING OVERVIEW & ASSESSMENT OF FRACTURE TOUGHNESS AND FATIGUE CRACK GROWTH THRESHOLD OF A WELDED JOINT CONSTITUENTOF A STEAM TURBINE ROTOR
应能源与动力工程学院热动力工程系主任袁奇教授的邀请，美国The Ohio State University，研究生办公室主任、理论与应用力学实验室主任Herman Shen教授于7月4日至7月11日来我校进行学术访问，并在期间举行系列学术讲座，欢迎各位老师和同学届时参加讲座并讨论交流。
讲座二: THE OHIO STATE UNIVERSITY COLLEGE OF ENGINEERING OVERVIEW & ASSESSMENT OF FRACTURE TOUGHNESS AND FATIGUE CRACK GROWTH THRESHOLD OF A WELDED JOINT CONSTITUENTOF A STEAM TURBINE ROTOR
Established in 1870, The Ohio State University has focused on engineering and the sciences since its beginning. The Department of Mathematics and Engineering was one of the original seven departments, and in 1882, the SchoolofEngineeringwas instituted. Today, we offer 13 undergraduate and 17 graduate engineering programs through our 11 engineering departments, as well as two undergraduate and three graduate degrees from the Knowlton School of Architecture. Ohio State is the largest, most comprehensive public research university in the country, ranked in the top 25 of all public universities overall in both research and education and ranked 7th in public-university research expenditures programs, 12th overall.
Many power station components for example, steam turbine rotors are joined by welding. During operations, these welded joints are exposed to high temperature corrosive environments severely experiencing cyclic or fatigue loadings. The base metal (BM), weld metal (WM) and heat affected zone (HAZ) of a welded joint constituent have different microstructural and mechanical properties and there can also be a presence of thermal residual stresses in these locations. As a result, the welded joints of a steam turbine rotor become the most vulnerable to fracture during operations. After exceeding a threshold value (fracture toughness), crack growth can initiate and continue through the welded joint constituents and finally can lead to a catastrophic failure of the turbine rotor. In order to ensure safety and reliability of steam turbine welded rotors, a thorough investigation focusing on evaluation of crack initiation, growth, and resistance parameters of BM, WM and HAZ of a steam turbine rotor welded joint constituent will be presented. Fatigue crack growth rate (FCGR) tests were performed first to determine the fatigue crack growth properties of welded joints of a steam turbine rotor by constructing fatigue crack growth curves. A single edge notch bend (SENB) specimen was loaded in a three-point bend fixture at room temperature. The fatigue crack growth parameters (C and m) were assessed for BM, HAZ and WM. In addition, the values of fatigue threshold of BM, WM and HAZ were obtained and compared in order to determine which location is more susceptible to crack initiation during services.
Professor of Mechanical & Aerospace Engineering, The Ohio State University, received his M.S. & Ph.D. degrees in Aerospace Engineering fromUniversityofMichiganin 1986 and 1989, respectively. He joined the faculty of the Aerospace Engineering at The Ohio State University in August 1989. For the past twenty six years, he has pioneered developments in structural health management framework and fatigue life prediction schemes for gas turbine engines, advanced composites, and adhesive joints. He is a recipient of the Air Force Research Initiation Award in 1991, ALCOA Science Foundation Award in 1995, and The Ohio State University College of Engineering Lumley Research Award in 2001. Dr. Shen has published more than 200 journal papers, book chapters, conference papers and technical reports. Dr. Shen has received thirty major research grants/awards with total over 6 million US dollars from NASA, AFRL, NSF, NAVAIR, DoE, GE, Idaho National Labs, Boeing, DAGSI, Pratt & Whitney, Lockheed Martin, GM, & Honda R&D.