준정적 압입 손상에 의한 하니컴 샌드위치 복합재료 구조물의 잔류강도에 관한 연구

Abstract

Sandwich honeycomb structures were developed with increasing hardness and strength, which led to its widespread use in airplane construction, and in automobiles and high-speed trains.

In this study, produced light weight structure widely appropriated sandwich honeycomb plate specimens to evaluate structural characteristics and make an experiment on edge-wise compressive and 3-point bending tests to honeycomb sandwich composite specimens.

To understand of deformation and fracture responses of composite sandwich plate subjected to quasi static indentation of a hemispherical-nose indenter. It was classified three steps for estimate residual strength of specimens after damage, Case 1 exhibits the early stage of the indentation process when the Aluminum honeycomb core starts to yield; Case 2 corresponds to deeper indentation depths when both the skin and the core yield; Case 3 presents cracked skin with crushed aluminum honeycomb core. Based on the results of quasi static indentation test, conducted an experiment that three steps applied at compression and 3-point bending test specimens.

After quasi-static indentation damage, compressive and bending strength were decreased according to the increase of indentation depth. It was cause by the indentation load. Quasi-static indentation load make decrease mechanical strength of the specimens with damage of facesheet and core crushing.

In the edge-wise compressive tests, the residual strength was decreased and In the CASE 3, cracked the facesheet and crushed core, the residual strength was rapidly decrease hold 35% of the one's strength. It is cause of excessive critical damage of facesheet, in case of edge-wise compressive at the specimens the facesheet mainly take charge of the compressive force

3-point bending test was classified according to tension and compression of damage area. Generally the strength is decrease in case of damaged specimens but the residual strength was increase slightly in case of the extent of the damage was small like CASE 1. It was considered that deformed specimens internal of compressive residual strength was increased the bending strength. But the extent of the damage was more than that, bending strength decrease rapidly in case of CASE 2 and CASE 3.