항공기 Butt Lap Joint 볼트연결 구조부의 손상허용성 시험 및 평가에 대한 연구

Abstract

본 연구는 항공기 주익이나 동체 표피구조의 Butt Lap Joint 연결부 볼트구멍 주변에 내재된 짧은 모서리 균열을 가진 시험편 구조에 대하여 설계 예상수명 동안의 비행하중스펙트럼하에서 피로균열성장 시험을 수행하고 모서리 균열에 대한 기존의 3차원 응력강도계수 계산식을 이용하여 균열성장해석을 수행한 결과와 실험결과를 비교함으로써 Butt Lap Joint 구조의 손상허용성 평가를 수행하였다.

The prediction of fatigue crack growth on the basis of the linear fracture mechanics is in accordance with the cases of through-thickness-cracks or long cracks, however the crack growth pattern of corner crack which is located at joint holes is different.

The behaviours of such a short corner crack play an important role on the damage tolerance life of aircraft structures. In this paper fatigue crack growth tests are carried out on the butt lap joint specimens with small corner crack on the bolt hole under expected flight-by-flight load spectrum. And the damage tolerance evaluation is also performed for the design condition of 2 life times.

The prediction of fatigue crack growth on the basis of the linear fracture mechanics is in accordance with the cases of through-thickness-cracks or long cracks, however the crack growth pattern of corner crack which is located at joint holes is different.

The behaviours of such a short corner crack play an important role on the damage tolerance life of aircraft structures. In this paper fatigue crack growth tests are carried out on the butt lap joint specimens with small corner crack on the bolt hole under expected flight-by-flight load spectrum. And the damage tolerance evaluation is also performed for the design condition of 2 life times.