超輕飛機結構設計與分析

Structure Design and Analysis of a Ultralight Airplane

高懷恩(Huai-En Kao)

指導教授 ： 胡惠文

國立屏東科技大學/工學院/車輛工程系所/碩士(2009年)

https://doi.org/10.6346/NPUST.2009.00220

摘要

本研究主要目的是用有限元素分析探討超輕飛機結構設計，包括結構模態、結構剛性與碰撞強度分析。執行整機結構分析前必須先對確認整機主結構之有限元素等效模型，然後進行整機剛性及碰撞才能獲得準確的分析結果。首先建立整機主結構有限元素分析模型，並且進行模態分析，其材料機械性質是由拉伸試驗取得。整機主結構之有限元素模型可以經由量測重量、重心及實驗模態驗證比對，完成整機主結構並將動力系統及相關配件建立完成整機全模型。然後進行整機結構剛性分析，包括：瞬間爬升、瞬間下降及瞬間爬升負載條件下，整機結構產生最大變型與最大von Mises應力。最後進行整機碰撞分析，採用結構材料彈塑性模型為Piecewise Linear Plasticity Model，此模型考慮應變率對於材料變形行為的影響，適用於金屬等向材料的塑性變形分析，其中應變率參數是經由衝擊試驗所獲得的材料參數。並探討整機結構在不同角度與速度下降落，整機結構變形及能量吸收差異。

關鍵字

超輕飛機 ； 有限元素分析 ； 實驗模態分析 ； 結構模態 ； 結構剛性分析 ； 衝擊測試 ； 結構碰撞分析

並列摘要

This research presents the structural design and analysis, including normal mode , structural stiffness and impact strength, for Ultralight Aircraft by using Finite Element Analysis (FEA). The finite element model of the full aircraft structure is established by using the software ANSYS. Static tests are first conducted on the main aircraft structure to obtain the weight and center of gravity in order to validate the finite element models. The mechanical properties of aircraft structures are obtained from the tensile tests. Normal mode analysis was performed to obtain the natural frequencies and associated mode shapes of the aircraft structures. The CFD software, Fluent, is used to analyze the aerodynamics to obtain the loading conditions under two cases, i.e. abrupt rising and abrupt descending at full speed. The loading conditions are then entered to the finite element analysis software, ANSYS, to analyze the deformation and stress levels in aircraft structure. Impact analysis is performed by using a software LS-DYNA. The Piecewise Linear Plasticity Model is used to simulate the dynamic behavior of structural materials. The material constants of this model are obtained from the bending impact tests of the aircraft structure. The significant results provide the designer the guidance of reinforcement design of the aircraft.

並列關鍵字

Ultralight aircraft ； Finite element analysis ； Experimental modal ； Normal mode analysis ； Structure stiffness analysis ； Impact test ； Impact analysis

參考文獻

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