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首页> 外文学位 >Impact of Bolt-Nut Interface Modeling Assumptions on the Calculated Low Cycle Fatigue Life of Aircraft Engine Turbine Rotor Bolted Joints.
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Impact of Bolt-Nut Interface Modeling Assumptions on the Calculated Low Cycle Fatigue Life of Aircraft Engine Turbine Rotor Bolted Joints.

机译：螺栓-螺母接口建模假设对飞机发动机涡轮转子螺栓连接的低周疲劳寿命的影响。

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摘要

Finite element analysis is used extensively in the aircraft turbine engine industry to predict stresses to calculate low cycle fatigue (LCF) life. An accurate prediction of stresses is especially important to a specific subset of engine hardware that is defined by the FAA as life-limited parts (LLP's). LLP's include rotor and major structural parts such as disks, spacers, hubs, shafts, high pressure casings, and non-redundant mount components. A failure of an LLP can lead to a potentially catastrophic event due to non-containment of high energy debris, uncontrolled fire, or a complete inability to shut the engine down. Under-predicted stress can cause the life limits to be set too high, which is a safety hazard. Over-predicted stress can cause the life limits to be set too low, which adds cost due to the need to replace expensive engine hardware more frequently. High fidelity stress analysis is necessary to appropriately set LCF life limits.;One common engine feature analyzed with 3D stress analysis is a rotor bolted joint. Geometrical features associated with bolted joints such as holes, fillets, and scallops cause stress concentrations. Often the life limiting feature in a rotor LLP is a geometrical feature in close proximity to the joint. Unfortunately, the detailed stress analysis associated with accurately predicting stress in the joint is costly and time consuming. Analysis assumptions that can simplify the effort, yet still produce accurate results, would be valuable to the industry.;The focus of this study is on the bolt-nut interface modeling assumptions associated with a rotor bolted joint stress analysis for LCF predictions. A 3D finite element model of an actual aircraft engine rotor bolted joint is created. A series of eleven cases are analyzed and compared to investigate how the thread modeling assumptions affect the calculated life in the mated rotor LLP hardware. Walker-adjusted alternating stress, sigma0,alt , is used to measure the life impact.;The impact is limited to the edges of the two critical features closest to the bolt-nut interface. The results demonstrate that factors such as the thread mesh density, elastic versus elastic-plastic bolt/nut material properties, and the inclusion of the helical thread shape have only minor impact. The inclusion of contact elements at the interface instead of couples has a moderate impact of 1.1 to 1.2 ksi. When couples are used, the placement of the first couple is critical, impacting the results by 1.1 to 2.6 ksi. Also, when couples are used to join the interface, the explicit inclusion of the thread shape has only 0.5 to 0.6 ksi impact.
机译：有限元分析在飞机涡轮发动机行业中广泛使用，以预测应力以计算低周疲劳（LCF）寿命。对于由FAA定义为使用寿命有限的零件（LLP）的发动机硬件的特定子集，压力的准确预测尤其重要。 LLP包括转子和主要结构部件，例如磁盘，垫片，轮毂，轴，高压机壳和非冗余安装组件。 LLP的故障可能会导致潜在的灾难性事件，这是由于未包含高能碎屑，失控的起火或完全无法关闭发动机而导致的。压力不足会导致寿命极限设置过高，这是安全隐患。过度预测的压力会导致寿命限制设置得太低，由于需要更频繁地更换昂贵的发动机硬件而增加了成本。要正确设置LCF寿命极限，必须进行高保真度应力分析。通过3D应力分析分析的一种常见发动机特征是转子螺栓连接。与螺栓连接相关的几何特征（例如孔，圆角和扇贝）会导致应力集中。通常，转子LLP中的寿命限制特征是非常接近关节的几何特征。不幸的是，与准确预测关节应力相关的详细应力分析既昂贵又耗时。可以简化工作量但仍能产生准确结果的分析假设对行业而言将是有价值的。本研究的重点是与螺母螺栓界面应力分析相关的螺栓螺母界面建模假设，以进行LCF预测。创建实际飞机发动机转子螺栓连接的3D有限元模型。分析并比较了一系列的11种情况，以研究螺纹建模假设如何影响配对转子LLP硬件中的计算寿命。沃克调整后的交变应力sigma0，alt用于测量寿命影响。;影响仅限于最靠近螺栓螺母界面的两个关键特征的边缘。结果表明，诸如螺纹网眼密度，弹性与弹塑性螺栓/螺母材料性能以及包含螺旋螺纹形状等因素的影响很小。在界面上包括接触元件而不是一对接触元件，会产生1.1至1.2 ksi的中等影响。当使用一对时，第一对的放置至关重要，从而将结果影响1.1至2.6 ksi。同样，当使用偶对连接界面时，螺纹形状的明确包含仅影响0.5至0.6 ksi。

著录项

  • 作者

    Jensen, Luke.;

  • 作者单位

    Tufts University.;

  • 授予单位 Tufts University.;
  • 学科 Mechanical engineering.
  • 学位 M.S.
  • 年度 2012
  • 页码 121 p.
  • 总页数 121
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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