隨著飛機的發展，飛機設計的概念也不斷進行修正。幾次重大飛行事故顯示安全壽期與失效安全的設計概念都無法保證飛機結構的安全。目前的FAA航空法規中，任何失效後會導致重大事故的結構件均應視為損傷容忍規範的結構件。起落架為輕航機最主要的結構件之一，因此其損傷容忍分析是相當重要的。 本研究的目的是利用有限元素軟體FRANC2D與壽期分析軟體AFGROW進行輕型運動航空載具之起落架損傷容忍模擬分析，並探討不同初始裂紋位置與不同材料對起落架之壽命影響。材料為鋁合金6061-T6、6061-T651、2024-T3、7076-T6、鈦合金Ti-6Al-4V以及合金鋼4340；負載則是考慮輕航機CH701設計之最大起飛重量450kg。 由損傷容忍分析結果得知，當起落架與機身接合處存在1mm初始裂紋負載450kg下，6061-T6裂紋擴展壽命為48000次。與6061-T6相比較，7075-T6、2024-T3、6061-T651起落架裂紋擴展壽命分別增加21%、156%與236%。鈦合金及合金鋼裂紋擴展壽命高出鋁合金甚多，鈦合金Ti-6AL-4V裂紋擴展壽命是鋁合金6061-T6的15倍，合金鋼4340裂紋擴展壽命為6061-T6的27倍。 The philosophies of aircraft design were changed with aircraft development. Several aviation accidents show that safe-life design and fail-safe design cannot ensure structure safety of operation. In Federal Aviation Regulations, for each part of the structure which could contribute to a catastrophic failure must also be evaluated by damage-tolerance analysis. Landing gear is one of major light-sports aircraft structures, so damage-tolerance analysis is important.
The purpose of this study is to use finite element analysis software FRANC2D and crack growth analysis software AFGROW to simulate damage-tolerance behavior in light-sports aircraft landing gear, and discuss the results of initial crack locations and materials. Materials are aluminum alloy 6061-T6, 6061-T651, 2024-T3, 7075-T6, titanium Ti-6Al-4V and alloy steel 4340. Landing gear load is 450kg from CH701 maximum take-off weight.
The results showed that crack propagation life of 6061-T6 landing gear was about 48,000 cycles with 1mm initial crack and 450kg loading. Compare with 6061-T6, crack propagation life of 7075-T6, 2024-T3, 6061-T651 landing gear increased by 21%, 156%, 236% respectively. The crack propagation life of titanium and alloy steel were much higher than aluminum. Life of Ti-6Al-4V was 15 times higher than 6061-T6,and life of 4340 steel was 27 times higher than 6061-T6.
