Ulsan National Institute of Science and Technology · 工学
Professor Wooseok Ji's research lab specializes in computational mechanics and multiscale modeling of advanced engineering materials, with a focus on the finite element analysis of composite and sandwich structures. The lab investigates fundamental issues in constitutive modeling, such as work-conjugacy in finite strain formulations and the objective stress rates in 3D solid analysis, to ensure accuracy in predicting buckling and instability behaviors. Research also extends to progressive damage and failure analysis of fiber-reinforced composites, incorporating material variability and manufacturing uncertainties through probabilistic frameworks. Additionally, the lab develops homogenization techniques to predict effective thermal and mechanical properties of complex textile composites across multiple scales.
Figures are computed from collected data and may differ slightly.
This paper is concerned with two issues that arise in the finite element analysis of 3D solids. The first issue examines the objectivity of various stress rates that are adopted in incremental analysis of solids. In doing so, it is revealed that large errors are incurred by an improper choice of stress rate. An example problem is presented to show the implications of the choice of stress rate. The second issue addresses the need to maintain work-conjugacy in formulating and solving bifurcation b
A two-dimensional mechanical model is developed to predict the global and local buckling of a sandwich beam, using classical elasticity. The face sheet and the core are assumed as linear elastic isotropic continua in a state of planar deformation. The core is assumed to have two deformation modes: antisymmetrical and symmetrical with respect to the core geometric midplane. Characteristics of the two deformation modes and the corresponding buckling behavior are shown and it appears that they are
Many finite element programs including standard commercial software such as ABAQUS use an incremental finite strain formulation that is not fully work-conjugate, i.e., the work of stress increments on the strain increments does not give a second-order accurate expression for work. In particular, the stress increments based on the Jaumann rate of Kirchhoff stress are work-conjugate with the increments of the Hencky (logarithmic) strain tensor but are paired in many finite element programs with th
A sandwich beam buckling problem is studied here using two-dimensional elasticity to model the beam constituents. The global and local instability of such a beam with orthotropic constituents under various boundary conditions are investigated. The face sheet and the core are assumed to be linear elastic orthotropic continua. General buckling deformation modes of the sandwich beam subjected to uniaxial compressive loading are considered. The appropriate incremental stress and conjugate incrementa
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