【作者】 任亮；

【导师】 沈海军；

【作者基本信息】 南京航空航天大学 ， 飞行器设计， 2008， 硕士

【摘要】 疲劳破坏是工程结构和机械失效的主要原因之一,据统计约有50-90%的机械结构的破坏属于疲劳破坏,引起疲劳失效的循环载荷的峰值往往远远小于根据静态断裂分析估算出来的“安全载荷”,产品的疲劳寿命是现代设计中一个重要指标,疲劳分析在结构设计中占有重要的地位。本文针对ANSYS疲劳分析的不足,利用ANSYS提供的参数化程序设计语言(APDL)、用户界面设计语言(UIDL)和二次开发专用语言(TCL/TK),对ANSYS进行二次开发,开发出了与ANSYS界面风格一致的FatigueTool程序模块。首先,对有限元模型进行应力分析,应用三峰谷计数法对载荷谱进行循环计数,结合材料的S-N曲线和Miner累积损伤理论,估算疲劳寿命,以叉车为计算模型,实现其全场的寿命可视化;其次,出于有限元分析对大量的时域信号处理困难的考虑,本文采用基于频域的功率谱密度法(P.S.D法)计算随机振动下构件的疲劳寿命,并结合导弹吊挂的算例,实现寿命可视化;再者,针对Miner线形累积准则的不足,考虑载荷加载的顺序效应和累积损伤统计分散性,结合汽车前轴的算例,计算出疲劳累积破坏概率,实现其全场的可视化,从另一个侧面来反映载荷对构件造成的疲劳破坏;最后,借助试验设计中拉丁超立方抽样和响应面近似模型技术,构造出目标函数和约束条件,采用主要目标法,结合飞机起落架中扭力臂的算例,开发出参数化建模程序,实现对零件的基于寿命的结构优化设计。实例计算表明,本文基于ANSYS二次开发的FatigueTool模块能够很好的应用于实际,程序是成功的有效的。更多还原

【Abstract】 Fatigue rupture is the main cause of mechanical failure in engineering structure and mechanism. According to survey, about 50-90% of the mechanical failure is fatigue rupture. The peak value of cyclic loading which brings fatigue rupture is always far less than the safe loading predicted by static analysis Fatigue life is one of the most important guideline in modern production design, and it also plays an important role in structure design.Considering the limitation of fatigue analysis in ANSYS, ANSYS APDL(Parametric Design Language)、UIDL (User Interface Design Language) and TCL/TK (Tool Command Language) are used to make secondary development in ANSYS. The FatigueTool module is developed, which can be used to predict fatigue life and realize the visualization of fatigue life.First of all, the finite element model of forklift is made stress analysis, the "Three peaks and valleys" method is used in counting the loop number, fatigue life is predicted with the S-N curve of material and Miner damage cumulative rule, and then the visualization of "entire field" fatigue life is carried out. Secondly, because of difficult of dealing with much time domain signal with FEA, the method based on power spectral density is used to predict the fatigue life of the pothook for X-typed air-air missile. Once more, aim at shortage of Miner linear damage cumulative rules, considering the order effect load spectrum and statistical dispersibility of damage cumulative, a method is used to calculate the failure probability. Finally, a strategy of anti-fatigue optimum design based on design of experiment (DOE) and response surface model (RSM) is proposed, object function and constraint condition is constructed, with the main object method, the structure-life optimization of the undercarriage force-arm for Y-typed fighter is carried out.The present examples show that the developed FaitgueTool module is effective and useful.更多还原