내부구조체 결함이 전단변형 가능한 반구형 내부구조체를 가진 초경량 금속 샌드위치 판재의 충격거동에 미치는 영향 분석

Abstract

The performance and properties of sandwich plate with three-dimensional inner structures are dependent on the shape and material of the inner structures. Hence, various researchers related on the sandwich plate with three-dimensional inner structures have an interest in the influence of the defects in the sandwich plate on the static and dynamic behaviors. The objective of this thesis is to investigate into the influence of defects of internal structures on the impact behaviors of the lightweight sandwich plate with deformable sheared dimple inner structures. Initial defects of sandwich plate with deformable sheared dimple inner structures have been observed to estimate candidate representative defect modes. From the results of the observation, two types of radius defect mode and three types of thickness defect mode have been estimated. Each radius defect mode has classified three types of sub-defect mode according to occurrence region of the radius defect. In order to investigate into the influence of defect modes on the impact behaviors of the sandwich plate, three-dimensional finite element analysis has been performed using ABAQUS V6.11 Explicit module. The results of FE analyses have been compared to those of drop impact experiments from viewpoints of the force per with-deflection curve, the absorbed energy-deflection curve, the deformed shape, and the amplitude of skin wrinkling. From the results of the comparison, a dominant defect mode has been estimated. In order to estimate the failure map and the normalized impact energy- the normalized absorbed impact energy curve, several finite element analysis have been carried out using finite element model with the dominant defect mode. Three types of failure modes have been chosen via the investigation of the deformation shapes. Through the failure mode fitting according to impact conditions, failure maps for the sandwich plate with deformable sheared dimple inner structures have been obtained. In addition, the normalized impact energy- the normalized absorbed impact energy curves for different normalized impact radius have been created using curve fitting.