国际创新研究期刊》的研究在科学、工程和技术
菜单ISSN在线(2319 - 8753)打印(2347 - 6710)
ISSN在线(2319 - 8753)打印(2347 - 6710)
马丹库马拉M C1,Nandish。V r .2Madhu E3
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通常涡轮叶片受到离心力由于高转速和高还在非常重要的环境条件。这样失败了涡轮叶片疲劳和蠕变是常见的。高周疲劳(HCF)燃气轮机是一个经验丰富的组件的燃气轮机的主要问题。因为这个高周疲劳会导致灾难性故障导致叶片和套管的损坏。材料中也扮演着重要的角色在减少失败,增加叶片的生活。数个研究进行了燃气轮机叶片材料的最佳材料其中镍基单晶就是其中之一。镍基单晶材料由于使用有效性在多晶叶片材料。HCF大共振应力造成的涡轮叶片设计的一个主要问题。疲劳分析是切口做线性变化的旋转叶片,交变应力,应变能、应力强度和生活的旋转叶片。损害的大小和位置的影响bladea年代生活报道。 Failure analysis of the rotating blade is carried to know the effect of the notch on the damaged blade and use it in critical conditions.
关键字 |
| 超级合金、单晶、高循环疲劳,低循环疲劳有限元分析 |
| 命名法 |
| P =由于旋转离心力效应。 |
| t =毫米板的厚度 |
| D =在毫米板的宽度。 |
| d =板的宽度至少在毫米截面。 |
| C。G =重心毫米的板。 |
| e =偏心(距离c .g轴向加载轴在毫米。 |
| 在mm Z =剖面模数。 |
介绍 |
| 汽轮机的主要功能是提取能量从高温气流来驱动压缩机和附件齿轮箱。燃气轮机叶片工作主要是在高温度梯度和受到高旋转速度。高速导致大型叶片的离心力和同时高温降低了阀瓣材料强度。航空航天关键部件的使用寿命是由退化和失败的模式如:疲劳、断裂,产生,蠕变,腐蚀,腐蚀、磨损等优点。疲劳是涡轮叶片失效的主要原因。金属承受反复循环荷载时表现出疲劳的影响。压力的大小在每个周期不足以导致失败与单个周期[1]。因此需要大量的周期失败的疲劳。疲劳可分为低循环疲劳和高循环疲劳。涡轮叶片失效的主要原因是高周疲劳。疲劳失效与反复循环荷载的结构成员。 The fatigue life of a structural member i.e. the number of load cycles it can survive is in general determined by the magnitude of the stress cycles. The exact relation between the magnitudes of the stress and the fatigue life depends on the material properties of the structural member. In general higher stresses lead to a shorter fatigue life. For some materials fatigue only occurs if stresses exceed a certain minimum level for other materials there is no minimal stress level. If the stresses that are present on the turbine blade during operation and the material properties of the turbine blade are known then an estimation of the fatigue life of the turbine blade can be made [2]. In Gas turbines, blades are usually the most critical engine components, which must endure substantial mechanical and thermal loading. Thus now a day we are using the single crystal nickel-base superalloy as the blade material. Fatigue life is enhanced by a low YoungâÂÂs modulus, this since the stresses will be lower for a crystal orientation with low stiffness compared to a direction with a higher stiffness when a constant strain is considered [3]. A problem arises in the turbine section it will significantly affect the whole engine function and, of course, safety of the aircraft. Excessive rotational speed of turbine is sometimes permissible for aircraft in the case of heavy operational conditions (i.e., short take off from landing ground). The joint between the turbine blade and the disc usually represents the most critical area from the point of view of the static and fatigue approaches [3], [4]. |
| 超合金材料的构成大部分建设在涡轮发动机由于其独特的物理和机械性能。在飞机引擎,它是典型的考虑density-normalized属性;因此合金密度,通常在7.7 - -9.0克/立方厘米,是特定的利益。优化相关的力学性能是至关重要的,依赖于高水平的控制和对制造过程的理解,因为机械性能强劲的微观结构的函数。力学性能主要关心的包括拉伸性能、蠕变、疲劳、和循环裂纹增长。根据组件设计的细节,这四个属性可能限制的生活。超级合金有相对高强度和极限应力[5]。与这些地区相关的负载主要是离心力和热应力。临界点的叶片疲劳寿命使用有限元应力计算结果和开发的故障判据。Bhat和r . Patibandla1金属疲劳和基本理论模型:一个回顾。 Basic fundamentals of fatigue failure in metal. Metals when subjected to repeated cyclic load exhibit damage by fatigue. The magnitude of stress in each cycle is not sufficient to cause failure with a single cycle. Large number of cycles is therefore needed for failure by fatigue. Fatigue manifests in the form of initiation or nucleation of a crack followed by its growth till the critical crack size of the parent metal under the operating load is reached leading to rupture. Patil A.A., ShirsatU.M 2 Investigated the metallurgical and mechanical examinations of the failed blade. The blade was made of a nickel-base alloy Inconel 738LC. The turbine engine has been in service for about 73,500 hrs before the blade failure. Due to the blade failure, the turbine engine was damaged severely. The investigation was started with a thorough visual inspection of the turbine and the blades surfaces, followed by the fractography of the fracture surfaces, micro structural investigations, chemical analysis and hardness measurement. The observation showed that a serious pitting was occurred on the blade surfaces and there were evidences of fatigue marks in the fracture surface. Mikael Segersäll 3 Nickel-Based Single-Crystal Superalloys. Superalloys are a group of materials that are used in high temperature applications, for example gas turbines and aero engines. Gas turbines are most commonly used for power generation, and it is only the very critical components which are exposed to the most severe conditions within the turbine, which are made from superalloy material. Lucjan Witek4 Failure analysis of turbine disc of an aero engine. The failure analysis of the turbine disc of an aero engine, installed in a certain type of aircraft. From the visual examination of the fractured surface, it was possible to observe beach marks, typical of fatigue failure. A non-linear finite element method was utilized to determine the stress state of the disc/blade segment under operating conditions. High stress zones were found at the region of the lower firtree slot, where the failure occurred. A computation was also performed with excessive rotational speed. Attention of this study is devoted to the mechanisms of damage of the turbine disc and also the critical high stress areas. Tresa M. Pollock, Sammy Tin5 Nickel-Based Superalloys for Advanced Turbine Engines: Chemistry, Microstructure, and Properties. The chemical, physical, and mechanical characteristics of nickel-based superalloys are reviewed with emphasis on the use of this class of materials within turbine engines. The role of major and minor alloying additions in multicomponent commercial cast and wrought superalloys is discussed. Microstructural stability and phases observed during processing and in subsequent elevated-temperature service are summarized. Processing paths and recent advances in processing are addressed. Mechanical properties and deformation mechanisms are reviewed. |
| Reza Jaya Wardhana, Arif Sugianto Nanang、我埃魏仁芳Jaya Wardana,焦油Karokaro, Hariyati Purwaningsih6,失效分析的第一阶段在航空发动机高压涡轮叶片涡轮PK-GSG波音b747 - 400。第一阶段的失败高压涡轮(HPT)在航空发动机涡轮叶片被冶金研究调查和失败的叶片的应力分析。镍基高温合金叶片是由。 |
数学公式 |
| 问题的复杂性是由假设机翼部分减少到一个平面矩形板长度的矩形板被认为是拥有维度= 200毫米,D = 50毫米,厚度t = 5毫米。估计交变应力的有限宽度矩形板单边缘半圆形缺口。平面长方形酒吧是受到旋转效应。矩形刀片旋转3000 - 15000 RPM。由于旋转叶片体验离心力的影响。这是由于叶片以来的惯性质量。所以叶片经历拉伸力在叶片的尖端同时弯曲应力也会影响叶片。这两股力量是足够的叶片和叶片被认为是失败与半圆形缺口中心。由于切口中心将会有部分centriod发生转移,所以少量的弯曲力进入画面。 |
| 方程用于转换的惯性力等效交变应力:当叶片开始在给定的转速旋转,产生的拉伸力(P)沿径向方向的叶片长度[6]。 |
| 由于旋转离心力效应是由 |
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| 交变应力的计算通过使用上述方程相应的离心力。 |
有限元分析方法 |
| 有限元分析数值方法。传统上,固体力学的一个分支。如今,一个物理问题的常用方法。数值解甚至非常复杂的应力问题现在可以获得通常使用有限元分析,和治疗方法是非常重要的,即使是入门材料力学。一个复杂的问题分成小的、简单的问题,可以解决用现有的材料力学和数学工具的知识。将模型划分为小块的过程称为啮合如图3所示。每个元素的行为是众所周知的在所有可能的支持和负载场景。有限元方法是使用元素和不同的形状。元素有着共同的点称为节点。这里的分析是由使用单晶镍基超合金的性质。 Now consider single semicircular notch having the notch radius of 2mm on one side of the rectangular plate is considered having dimension of length L = 200mm, D = 50mm and thickness t = 5mm. Estimation of the alternating stress for the Finite Width Rectangular Plate with Single Edge Semicircular notch. Here the flat rectangular bar is subjected to rotational effect. The rectangular blade is rotated with 3000 to 15000 RPM. Due to the rotational effect the blade experiences centrifugal forces. This is due to the inertia since the blade is having mass. So that the blade experiences tensile force at the tip of the blade at the same time bending stress will also affects the blade. These two forces are enough for the blade to fail and also the blade is considered with semicircular notch at the centre. Due to the notch at the centre there will be partial shifting of the centriod occurs, so small amount of bending force comes in to picture. The result obtained from the ansys is compared to the theoretical results. The graph is as shown in Fig 2. In that alternating stress is plotted against the speed of the blade. From the Fig 2 we can compare the values of alternating stresses calculated from theoretical and software. There will be variation of 12% between the alternating stresses calculated from theoretical and software. |
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结果和讨论 |
| 矩形板的尺寸长200毫米,宽50毫米和5毫米厚度。板的旋转半径是250毫米。半圆形的大小级的半径2毫米,4毫米,6毫米,9毫米和12毫米的距离30毫米,60毫米,100毫米,140毫米和180毫米的根叶片前缘的盘子。分析了U-notches深度b = 1毫米和b = 2毫米的切口半径上面提到的相同。板使用ANSYS建模网状和分析。矩形板的有限元分析进行旋转15000 rpm分析研究疲劳分析的半圆形和U-notches刀片沿叶片的前缘。 |
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| 从结果显示在图4、5和6就可以观察到的压力将最大缺口半径增加同时压力减少随着切口从根到叶。随着切口半径对叶片的尖端应力几乎是常数无关的切口半径。在图4中可以表明,压力将最高等级时在图5和图6根和压力高而无花果4因为切口的大小。当缺口半径从根或切口转向压力是恒定的。从这个很明显,根附近的缺口存在的压力是最大的。从这个维修工程师可以决定是否损坏的叶片可以使用根据损伤和损伤的位置。 |
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| 由于等级被认为是不同叶片前缘的线性应力强度起着重要的作用。从上面的图7、8和9就可以观察到,它更类似于交变应力的分布。应力强度增加时,切口附近存在刀片的根源。当切口尖端附近的应力强度是恒定的。半圆形缺口时的应力强度很小,U-notches应力强度增加,由于高应力集中。叶片应力强度几乎是常数级离根。通过了解叶片的应力强度的失败可以预测。 |
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| 应变能的能量储存在体内。应变能量取决于位移和切口半径。应变能随着切口半径增加而延长。因为随着切口半径的增加位移也会增加。从图10、11和12很明显,应变能几乎是常数级时远离叶片的根源。最大应变能可以在12毫米的切口半径存在根附近。图11和图12中应变能很高由于切口尺寸的增加。应变能量取决于最大应力。自应力高等切口半径,将最大应变能量也最大。 |
| 的生活估计是一个重要的参数在分析叶片的失败。比较生活的叶片和切口,没有缺口。叶片的生活没有等级高的生活因为没有应力集中造成损害。误差百分比的生命将是切口半径增加,当切口附近存在刀片的根源。错误的将小离根的等级。从图13、14和15就可以得出结论,可以使用叶片如果破坏也远离叶片的根和它提供的信息损失的大小。 |
结论 |
| 在这项研究中不同叶片线性建模,研究疲劳寿命通过考虑损伤叶片的前缘。当损伤深度很小,它可以被认为是半圆形的同时如果损伤深度高认为U -切口。叶片的最大生命时不会有弹簧轴上的刀片。叶片的生活主要依赖于叶片上的损伤和破坏的位置从根。的损害是远离根叶片叶片的生命更重要的是它可以从图表所示。这样我们就可以忽视伤害靠近叶片的尖端。图中结果表明,生命的百分比变化增加切口大小及其位置。比例非常小离根当等级。同样U-notch时比例高。交变应力和应力强度也增加切口半径增加根同时交变应力和应力强度几乎不变,当切口尖端附近的刀刃。 |
引用 |
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