Papers by Author: In Lee

Abstract: In this study, the stabilization of thermoelastic unstable postbuckling in cylindrical piezolaminated panels was investigated by applying piezoelectric actuation. In order to derive the finite element equations of motion of the active piezolaminated cylindrical panels, the total Lagrangian formulation was derived using the Hamilton’s virtual work principles for largely deformed structures with small strain. For the purpose of finding the load-displacement tracking, a cylindrical arc-length method was applied to the iterative Newton-Raphson scheme. Present results show that the eccentric piezoelectric patch can passively remove the unstable postbuckling and the snap-through without piezoelectric actuation. Also, the thermoelastic snap-through can be successfully suppressed by using a piezoelectric actuation.

Abstract: Aeroelastic tailoring studies using effective computational method with genetic algorithm have been conducted to find an optimized lamination set which give minimum structural weight. The efficient and robust computational system for the flutter optimization has been developed using the coupled computational method based on the micro genetic algorithm. It is shown that the wing structural weight with both divergence and flutter constrains can be significantly reduced using composite materials with proper optimum lamination compared to the case of isotropic wing model.

Abstract: The thermomechanical behavior of SMA thin film actuator and their application are investigated. The numerical algorithm of the 2-D SMA thermomechanical constitutive equation is developed using user material (UMAT) subroutine written by FORTRAN. For the numerical results of SMA thin film, the ABAQUS finite element program has been utilized with UMAT subroutine of the numerical algorithm of SMA. The application of SMA thin film for the membrane pump actuator is demonstrated.