Keynote Speakers
Nao-Aki Noda
Professor Emeritus, Kyushu Institute of Technology, Mechanical Engineering Department, Kitakyushu 804-8550, JapanConcurrent Professor: Northeastern University, Henan University of Science and Technology, East China Jiatong University
Guest Professor: Shandong University, Shandong University of Technology
Speech Title: Study on sleeve slip mechanism and slip damage through load shifting simulation and miniature roll experiment for development of next-generation sleeve assembly type rolls
Abstract: Next generation rolls such as super-cermet rolls and all-ceramic rolls can be manufactured using only sleeve assembly type rolls and have the advantage of being able to reuse the shaft by replacing the damaged sleeves. However, in some cases failures with unknown causes may occur such as circumferential slippage, shaft pull-out or residual bending deformation at the shrink-fit interface. Such slipping failures cannot be prevented by conventional design concept. This is because even if the resistant torque is greater than the motor torque, the circumferential slippage will occur, and the shaft will come off even if there is no external force. In order to prevent slip failures, we realize the phenomena through numerical simulations, and we clarify the localized slip accumulation that causes sleeve slip during roll rotation. We also identify the geometry of slipping defect through miniature roll experiments. Based on those results, we estimate the fatigue strength of sleeve assembly rolling rolls considering slip defects. The results show that by preventing the slip damage, the fatigue strength of sleeve rolls is almost equivalent to that of conventional solid rolls without shrink-fit.
Biography: Nao-Aki Noda, born in 1956, BA in Mechanical Engineering in 1979, and ME in Mechanical Engineering in 1981, both from Kyushu Institute of Technology, Japan. He received a Ph.D. in Mechanical Engineering in 1984 from Kyushu University, Japan. He worked at Kyushu Institute of Technology from 1984 as an Assistant Professor, Associate Professor and Professor. From 2022, he is a Professor Emeritus. 1) He analyzed the stress concentration factors (SCFs) for notched test specimens by using the body force method. Then, he proposed the SCF formulas within 1% error in their papers. The formulas provide SCFs under arbitrary dimension of the notch including blunt and sharp notches and shallow and deep notches in the specimens. Also, he rigorously solved several singular integral equations and obtained the exact variation of the stress intensity factors of a semi-elliptical surface crack. For those achievements related to stress analysis, he received JSMS Academic Contribution Award from Japan Society of Materials Science. 2) In joint research with Hitachi Metal, they first started developing all ceramic rolls for use in continuous galvanizing lines (CGLs). He contributed by clarifying methods for reducing tensile stress during immersion in molten metal and during operation. Regarding the ceramic rolls, the group received Sokeizai Industry Technology award from Materials Process Technology Center Japan. Shrink-fitting was found to be essential for the joint of such ceramic rolls, but on the other hand, the shaft slipped out during operation. He realized this new phenomenon in the numerical experiments and clarified that irreversible local slip accumulation causes the failure. Regarding this achievement, Nao-Aki Noda received and JSDE Best Paper Award from Japan Society for Design Engineering. 3) Regarding rolling rolls, he investigated the relation between heat treatment and residual stress through joint research with two roll manufacturing companies. In line with the actual situation, creep deformation was also incorporated into the analysis. Using the obtained residual stress as the initial condition, they also analyzed the stress during rolling clarifying the critical regions at the HSS/DCI boundary of the bimetallic roll and evaluated the fatigue strength of the roll. Regarding those collaborations, Nao-Aki Noda received JSMS Branch Distinguished Service Award. 4) There is an idea to shift the structure of rolling rolls to a sleeve assembly type, which can be a candidate to satisfy the requirements beyond the limits of current rolls as well as to reduce costs. However, even if the sleeve roll is designed so that it does not slip during rolling, the sleeve sometimes slips in the circumferential direction. This sleeve slip cannot have been explained by the conventional design criteria (driving torque < frictional resistance torque). Therefore, his group verified this by numerical experiments using load shifting method, and simulated experiments using miniature rolls. They clarified the process of damage on the inner surface of the sleeve. Regarding those collaborations, Nao-Aki Noda received JSME Materials & Mechanics Division Award, Contribution Award. 5) Nao-Aki Noda also studied several fastening elements. Nao-Aki Noda also showed that the adhesive strength can be expressed as a constant value of ISSF (Intensity of Singular Stress Field). He proposed a desirable specimen geometry of lap joint, which is not affected by bending deformation. He clarified the ISSF under pull out test and microbond test used to estimate fiber bonded strength in fiber reinforced composites. Regarding the achievement, he received JCOM Award for Scientific Papers from JSMS. Regarding a series of pioneering research on strength design in adhesive, joining and fastening, he received JSME Materials & Mechanics Division Award, Achievement Award.