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增压器压气机叶轮、轴套和轴采用过盈配合技术联成一体,这是典型的三维多体接触问题。本文以某柴油机涡轮增压器的压气机为例,采用有限元参数二次规划法,并结合多重子结构技术分析求解叶轮与轴套、轴套与轴的三维弹塑性有摩擦接触问题,针对不同的过盈量、摩擦系数和转速进行了大量计算,获得了叶轮、轴套与轴之间接触应力的相应分布规律。分析表明:随着叶轮与轴套间过盈量的增大,轴套的外表面与内表面的接触应力是线性增大的,而且内表面的接触应力增加较为迅速,这对于确定合理过盈量和改进设计具有参考意义。 相似文献
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The hypercompressor is one of the core facilities in low density polyethylene production, with a discharge pressure of approximately 300 MPa. A packing cup is the basic unit of cylinder packing, assembled by the interference fit between an inner cup and an outer cup. Because the shrink-fitting prestresses the packing cup, serious design is needed to gain a favorable stress state, for example, a tri-axial compressive stress state. The traditional method of designing the interference fit value for packing cups depends on the shrink-fit theory for thick-walled cylinder subject to internal and external pressure. According to the traditional method, critical points are at the inner radii of the inner and external cup. In this study, the finite element method (FEM) has been implemented to determine a more accurate stress level of packing cups. Different critical points have been found at the edge of lapped sealing surfaces between two adjacent packing cups. The maximum Von Mises equivalent stress in a packing cup increases after a decline with the rise of the interference fit value. The maximum equivalent stress initially occurs at the bore of the inner cup, then at the edge of lapped mating surfaces, and finally at the bore of the outer cup, as the interference radius increases. The traditional method neglects the influence of axial preloading on the interference mating pressure. As a result, it predicts a lower equivalent stress at the bore of the external cup. A higher interference fit value accepted by the traditional method may not be feasible as it might already make packing cups yield at the edge of mating surfaces or the bore of the external cup. Along with fatigue analysis, the feasible range of interference fit value has been modified by utilizing FEM. The modified range tends to be narrower and safer than the one derived from the traditional method, after getting rid of shrink-fit values that could result in yielding in a real packing cup. 相似文献
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In this article, the thermoelastic contact problem involving a functionally graded coating and a homogenous substrate is considered. Determination of subsurface stresses is highly critical in the design of mechanical assemblages due to fatigue and fracture failures resulting from contact loading. In such contact problems, cracking generally initiates at the locations of high subsurface stresses. The present study proposes a finite element methodology for the computation of subsurface stresses in functionally graded coatings subjected to frictional contact with heat generation. The method developed is based on iterations continued until convergence is observed in the contact zone heat flux values. Presented results illustrate the influences of various geometric and material parameters upon the subsurface stresses. 相似文献
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直线压缩机具有体积小、摩擦力小、效率高以及无油润滑等优点,其小型化设计在微电子冷却及微型空调领域具有重要的发展前景。利用Ansoft Maxwell有限元分析软件建立了动磁式直线电机模型,确定了谐振工况下直线电机结构及性能参数,通过数值积分分析了空载和负载工况下的活塞位移。根据理论分析和模拟,研制了对置式直线压缩机实验样机,压缩机总质量为1.2 kg,总长度为118 mm。实验结果显示:以R134a为制冷剂时,在冷凝压力为0.79 MPa、蒸发压力为0.39 MPa下,制冷量为57.3 W。模拟及实验结果对直线压缩机小型化设计具有参考价值。 相似文献
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A parametric method for the axial compressor 2D blade profiles is proposed in which the blade geometries are defined with
the parameters commonly used for blade definition, which ensures that the geometric significance is clear and an unreasonable
blade profile is not generated. Several illustrations are presented to show the fitting precision of the method. A novel response
surface model is proposed which regards the objective distribution function in the vicinity of a sample as normal school,
and then generates the response surface function in the whole design space by a linear combination of distribution functions
of all the samples. Based on this model, a numerical aerodynamic optimization platform for the axial compressor 2D blade profiles
is developed, by which aerodynamic optimization of two compressor blade profiles are presented.
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Translated from Acta Aeronautica et Astronautica Sinica, 2007, 28(4): 813–820 [译自: 航空学报] 相似文献
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AbstractFor given geometrical properties of a shrink fit, the interface pressure is decisive for reliable operation and should stay as large as possible during operation. Using an appropriate functionally graded material for the hub facilitates a less decreasing interface pressure with increasing angular speed and, moreover, substantial weight-reduction. However, temperature cycles may influence the interface pressure considerably, and if partial plastification occurs, even a permanent decrease may result. These issues are discussed by analytical means, and both homogeneous and inhomogeneous temperature fields in an initially elastic shrink fit with hollow steel inclusion and steel-aluminum FGM-hub are considered. 相似文献
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1 100 MW核电发电机是未来几年发展的主力机型,转子作为发电机中最关键的零部件,其运行时承受巨大的离心应力(本身旋转)和短路力矩(来自于电网)的作用,直接影响到发电机的安全运行;护环是汽轮发电机转子中承受应力最大的一个部件,为确保护环在运行中安全可靠,有必要对其在各种状态下的应力进行分析。主要通过ANSYS对1 100 MW级核电汽轮发电机的护环装配进行机械计算,对长搭接护环、短搭接护环进行计算和比较分析,并选取合适的过盈量以使得护环装配体中的各部件能满足设计要求,根据分析结果优化选择护环设计结构。 相似文献
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The problems involving periodic contacting surfaces have different practical applications. An inverse heat conduction problem
for estimating the periodic Thermal Contact Conductance (TCC) between one-dimensional, constant property contacting solids
has been investigated with conjugate gradient method (CGM) of function estimation. This method converges very rapidly and
is not so sensitive to the measurement errors. The advantage of the present method is that no a priori information is needed
on the variation of the unknown quantities, since the solution automatically determines the functional form over the specified
domain. A simple, straight forward technique is utilized to solve the direct, sensitivity and adjoint problems, in order to
overcome the difficulties associated with numerical methods. Two general classes of results, the results obtained by applying
inexact simulated measured data and the results obtained by using data taken from an actual experiment are presented. In addition,
extrapolation method is applied to obtain actual results. Generally, the present method effectively improves the exact TCC
when exact and inexact simulated measurements input to the analysis. Furthermore, the results obtained with CGM and the extrapolation
results are in agreement and the little deviations can be negligible. 相似文献
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探讨了如何利用双节点单元实现对混凝土大坝裂缝的长、宽、高等几何形态进行模拟;采用接触算法实现了对带缝大坝裂缝的物理特性模拟;结合实例,研究了此方法在裂缝的成因分析、影响因素以及预测裂缝发展等方面的应用。 相似文献
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Long‐term contact fatigue analysis of a planetary bearing in a land‐based wind turbine drivetrain 下载免费PDF全文
This paper presents an approach for performing a long‐term fatigue analysis of rolling element bearings in wind turbine gearboxes. Multilevel integrated analyses were performed using the aeroservoelastic code HAWC2, the multibody dynamics code SIMPACK, the three‐dimensional finite element code Calyx and a simplified lifetime prediction model for rolling contact fatigue. The National Renewable Energy Laboratory's 750 kW wind turbine and its planetary bearing were studied. Design load cases, including normal production, parked and transient load cases, were considered. To obtain the internal bearing load distribution, an advanced approach combining a finite element/contact mechanics model and a response surface model were used. In addition, a traditional approach, the Harris model, was also applied for comparison. The long‐term probability distribution of the bearing raceway contact pressure range was then obtained using Weibull and generalized Gamma distribution functions. Finally, we estimated the fatigue life of the bearing, discussed the differences of the methods used to obtain the bearing internal loads and analyzed the effects of the environmental conditions and load cases on the results. The Harris model may underestimate the inner raceway life by 55.7%, which can cause large load fluctuations along the raceways. The bearing fatigue life is very sensitive to the wind distribution and less affected by the transient and parked load cases. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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汽轮机套装叶轮接触问题的三维有限元分析 总被引:1,自引:0,他引:1
运用有限元分析软件SAMCEF,对某型号汽轮机套装叶轮与轴的过盈配合问题作三维模型计算分析,计算中采用接触单元处理过盈配合边界,得到了转子位移和应力分布,并对原来的过盈量设计进行了优化改进,在保证安全性的前提下减小了轮盘的接触应力。 相似文献
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涡轮盘-片耦合场及接触问题建模与分析的新方法 总被引:1,自引:0,他引:1
针对某燃气轮机盘-片,运用存储与导入的思想提出了一套耦合场及接触问题的建模和分析的新方法。文中采用PRO/E建立了轮盘和叶片的三维实体模型,并结合ANSYS软件建立了其耦合场及接触有限元模型,详细介绍了该问题的有限元分析方法。文章最后给出了算例,其分析结果证明了文中的建模及分析方法是较好的适合工程应用的新方法。 相似文献
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