Journal of the Korean Society of Propulsion Engineers (한국추진공학회지)

The Korean Society of Propulsion Engineers (한국추진공학회)
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Structure Safety Analysis of Composite Lattice Structure with Inspection Window

복합재 격자구조물의 점검창 형상에 따른 구조안전성 해석

  • Received : 2018.04.03
  • Accepted : 2018.07.23
  • Published : 2018.12.01
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Abstract

The purpose of designing composite lattice structure which applied to launching vehicle and tactical missile body is to minimize the thickness and weight for applied load. It is usually made of carbon fiber; fabricating with filament winding process over silicon mold, and provided with a window opening for inspection purpose if necessary. In this paper compression test is conducted without window opening in lattice structure and preliminary FEA is carried out to confirm its accuracy. And then FEA is performed for the case of window opening to evaluate the soundness and the safety factor of the structure. We have calculated for two kinds of window shape; rectangular one and hexagonal one. And we have calculated safety factors of the lattice structure with window opening in every case based on failure strength of rib and knot with varying the thickness and location of the window for hexagonal shape. Through our investigation, we have found out the followings; (1) the hexagonal shaped window is shown higher safety factor than rectangular one, (2) a window in a certain location is shown higher safety factor than others, (3) although the soundness of window structure is improved as increasing its thickness, a window of a certain thickness is shown higher safety factor than others because of stress concentration.

발사체 및 유도무기 기체에 사용되는 복합재 격자구조물은 구조물에 작용하는 하중을 고려하여 최소한의 두께와 무게로 설계되는 구조물이다. 이를 위하여 실리콘 몰드에 탄소섬유를 와인딩하는 공정으로 격자구조물을 만들며, 이때 발사체 및 유도무기 기체 내부의 장비 등을 점검하기 위하여 점검창을 설치하는 것이 일반적으로 요구된다. 본 논문에서는 필라멘트 와인딩 공정으로 제작된 실린더형 격자구조물에 대하여 압축시험을 수행하고, 이 구조물에 대한 유한요소해석을 수행하여 얻은 해석 결과를 설치된 격자구조물에 대하여 유한요소해석을 수행하였다. 또한 구조물의 리브(Rib)와 노트(Knot)의 파손강도를 통해 육각형 점검창의 두께 및 위치를 변수로 선정하여 수행한 유한요소해석 결과는 다음과 같다; (1) 육각형 점검창의 안전계수가 사각형 점검창 보다 높게 계산되었으며, (2) 수직 점검창이 상단 헬리컬 리브의 중간에 위치할 때 안전계수가 높게 계산되었고, (3) 구조안전성 확보를 위하여 점검창의 두께를 증가시킬 경우 구조물의 불연속 부분에 응력집중이 발생하므로 유한요소 해석을 통해 안전계수가 가장 높은 점검창 형상을 선정해야 한다.

Keywords

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