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Virtual fields method(VFM)
Virtual fields method is an inverse approach to identify material constants of constitutive law. Theoretical background of VFM is weak form equilibrium equation, the principle of virtual work. Also, VFM utilize full field measurement data during the mechanical test. By solving equilibrium equation using measured deformation field, material constants of constitutive law can be identified. VFM enables to obtain anisotropic material parameters or inhomogeneous material parameters with single mechanical test
Characterization of ductile fracture for the metallic materials
Estimation of the forming limit of materials is one of the main issue in the characterization of material properties. Conventionally, localization based forming limit diagram(FLD) is wildly used for the sheet metals and it was successful for the ferrous metals. Lightweight metals such as aluminum or magnesium alloys or high strength steels are more brittle compare to the conventional steel, so fracture point based criterion is needed. Usually, fracture of metallic materials are dependent on stress states such as stress triaxiality or lode angle parameter.
Friction model based microscopic contact mechanism of surface asperities
For accurate predictions of the formability and springback in the finite element sheet forming simulations, friction behavior between tools and sheet metal should be implemented exactly. However, friction behavior has been still modeled and implemented as a simple way though it is one of critical factors for accurate numerical simulations. Therefore, we proposed friction model based microscopic contact mechanism of surface asperities and predicted precise friction coefficient according to different contact conditions
Mechanics of composites materials
Composites structures, such as CFRP(Carbon Fiber Reinforced Polymer), metal-polymer multi layered sheets, have several merits in both mechanical and functional properties. Also, due to rising of safety problems in energy materials and electronic materials, which has composite structures, researches of its mechanical properties are crucial. To predict composite’s mechanical behaviors, precise constitutive modeling of each materials is needed. In addition, if inter-material effects are considered, accurate modeling of composites and designing of various novel composites in an mechanical aspect will be feasible.