Dr. Ryuta Kitamura, Department of mechanical engineering, Faculty of Engineering, Kanagawa University, Japan

Biography: Dr. Kitamura received PhD (eng.) from Yamaguchi University of Japan in 2015.3. He worked as an assistant professor at Tokyo University of Science from 2015.4-2019.3. He has been working as an assistant professor at Kanagawa University from 2019.4. His specialties are composite materials, material mechanics and finite element method, etc. In particular, he is familiar with the preparation and mechanical characteristic measurement of ceramic matrix composites (CMC) and finite element analysis of the interfacial sliding problem of fiber reinforced composites, and he authored “Formulation of off-axial interfacial debonding and sliding problem by constrained conditional finite element method” etc. In addition to the above, it is also deals with materials include CFRP, GFRP, CMC, WPC (wood plastic composite), evaluation methods include tensile test, bending test, SHPB test, AE measurement, DIC measurement, sampling moire method, and analysis methods include finite element method and molecular dynamics.

Speech Title: Constraint conditional finite element method for off-axial interfacial sliding of fiber reinforced composite

Abstract: In general, prevention of the fiber/matrix interfacial debonding is the key to strengthen polymer-based Fiber Reinforced Composites (FRC), whereas in Ceramics Matrix Composite (CMC), the fiber/matrix interfacial sliding is the main toughening mechanism. In the present study, the interfacial sliding problem was formulated by the Constraint Conditional Finite Element Method (CC-FEM). In this formulation, the equality of nodal displacements at the interface and the equilibrium of contact forces are assumed as constraint conditions, in which Coulomb's friction law is taken into account. As a distinguished advantage, the numerical solutions can be obtained by only one calculation without iterative algorism. In the previous papers, we treated the case such that the fiber in a CMC was oriented along the loading direction. But, in actual CMCs, the fibers are not necessarily oriented along the loading direction, and the fiber diameter also fluctuates along the axis. In this study, thus, the off-axial interfacial sliding problem was formulated, and the validity of CC-FEM was investigated by comparing with general-purpose finite element software ANSYS. The results show that, in the both cases of on- and off-axial interfacial sliding, the resultant stress distributions of the fiber and matrix agreed well with those of ANSYS. As compared to the case of on-axial interfacial sliding, the matrix stress recovered more steeply because of the higher equivalent frictional coefficient.

Keywords: Finite Element Method (FEM), Interfacial sliding, Coulomb's friction, Contact analysis, Ceramic Matrix Composites (CMC)