共查询到14条相似文献,搜索用时 156 毫秒
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基于有限元实体建模方法,建立了燃气轮机拉杆转子中两级叶盘系统有限元模型,分析比较了有无级间接触耦合作用下叶盘系统的模态特性,重点研究了轮盘级间接触耦合效应对叶盘系统频率转向特性的影响。研究表明,级间接触耦合作用下出现了叶盘耦合振动的复杂振动形式,振动能量不再局限于单级叶盘;级间耦合作用导致叶盘系统的频率转向特性发生改变,频率转向区内的模态不再高度密集,降低了叶盘系统对失谐的敏感度。建立了叶片刚度失谐的两级叶盘系统有限元模型并进行模态分析,结果显示失谐叶盘系统模态局部化程度较低。 相似文献
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在航空发动机叶-盘系统中,由于叶片失谐导致严重的振动局部化,造成局部叶片的高周疲劳,拟采用增加叶根干摩擦的方法降低失谐叶-盘系统振动幅值,减轻其振动局部化程度。基于微动滑移摩擦模型建立叶根阻尼器干摩擦力本构关系,采用等效椭圆代替阻尼器力与位移函数关系的迟滞回线,获得阻尼器的等效阻尼、等效刚度;将等效阻尼、等效刚度作用于叶-盘系统集中参数模型上,建立单个扇区三自由度整周失谐叶-盘系统动力学方程;采用谐波平衡法对其进行振动特性分析,讨论了叶根干摩擦对失谐叶盘系统振动特性的影响。结果表明:叶根摩擦能显著降低系统共振幅值;有叶根摩擦系统较无叶根摩擦系统的共振峰在频率上延后;增加叶根摩擦可有效降低失谐叶-盘系统的振动局部化程度。 相似文献
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针对叶片榫头与轮盘榫槽连接处间隙及摩擦,基于叶盘结构典型集中参数模型,建立含干摩擦、间隙的非线性动力学方程,研究失谐叶盘系统振动局部化。在叶身刚度随机失谐下分析叶盘系统对不同耦合刚度的固有特性及共振响应。结果表明,非线性谐调叶盘系统亦出现振动局部化现象。利用振幅放大系数对线性、非线性失谐叶盘系统振动响应局部化研究,振幅放大系数呈失谐阈值现象,且非线性干摩擦、间隙作用会降低失谐系统振动响应局部化程度。而谐调叶盘系统非线性振动,随气流激励力频率变化,系统呈非简谐单周期运动、多周期谐波运动、混沌运动等多种动力学行为。失谐因素存在会使非线性失谐叶盘系统动力学行为更复杂。 相似文献
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《振动与冲击》2019,(17)
通过在整体叶盘各扇区叶片上涂敷不同厚度的硬涂层可以将主动失谐减振与硬涂层阻尼减振技术简单而有效地应用于整体叶盘。为了探究该方法的减振特性,首先给出了利用单个失谐扇区的结构矩阵组集成完整主动失谐叶盘结构矩阵的方法,并利用泰勒展开和最小二乘法建立了叶片上的涂层厚度与涂层引起的叶片失谐矩阵这两者的近似关系。在此基础上,利用公称模态子集法对失谐叶盘结构进行减缩建模。接着,通过与完整有限元的计算结果对比验证了所提出的近似关系与减缩模型的正确性。最后,利用该减缩模型和蒙特卡罗模拟分析了行波激励下基于硬涂层的主动失谐叶盘振动特性。研究表明:叶盘基体随机失谐下,该方法可以明显降低整体叶盘的响应水平。 相似文献
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针对离心压缩机在复杂运行工况下的失谐与裂纹问题,研究裂纹与失谐对叶轮结构振动响应和振动局部化的影响规律。首先,采用三维有限元模型建立具有复杂几何形状的叶轮结构的定量分析模型,并通过在裂纹界面上定义接触的形式模拟裂纹的呼吸效应。其次,通过采用混合界面模态综合法对系统自由度进行缩减,以解决了采用三维有限元模型分析非线性系统动态响应时所存在的计算量大和收敛困难的问题。最终,采用Monte Carlo方法对含裂纹的失谐叶轮结构进行统计分析,研究随机失谐和裂纹故障对叶轮结构振动局部化的影响规律。结果表明裂纹和失谐都会对结构的振动响应产生显著的影响,并会导致振动能量的集中和振动局部化现象。 相似文献
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When interblade coupling is weak, the dynamic response of a bladed disk is very sensitive to the presence of uncertainties. Excessive response variation can be very harmful. Previous studies have indicated that introducing blade-to-blade difference in nominal design, known as intentional mistuning, could reduce the level of response variation. In this research, an efficient computational framework that yields the optimal design of intentional mistuning is developed to maximize the bladed disk reliability. Both the random uncertainty of blades and the interval uncertainty of disk connections are considered. The Metropolis–Hastings algorithm is applied to find the worst case response under interval uncertainty, and Monte Carlo simulation is employed to account for the random mistuning effect. A gradient-based approach is then established to find the minimum design modification needed to achieve a designated reliability level. Case studies are carried out to illustrate the effectiveness of the proposed method. 相似文献
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This article introduces a method of mistuned parameter identification which consists of static frequency testing of blades, dichotomy and finite element analysis. A lumped parameter model of an engine bladed-disc system is then set up. A bladed arrangement optimization method, namely the genetic particle swarm optimization algorithm, is presented. It consists of a discrete particle swarm optimization and a genetic algorithm. From this, the local and global search ability is introduced. CUDA-based co-evolution particle swarm optimization, using a graphics processing unit, is presented and its performance is analysed. The results show that using optimization results can reduce the amplitude and localization of the forced vibration response of a bladed-disc system, while optimization based on the CUDA framework can improve the computing speed. This method could provide support for engineering applications in terms of effectiveness and efficiency. 相似文献
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R. Luo 《Acta Mechanica》2012,223(7):1385-1396
This paper investigates the natural frequency of free transverse vibration of blades in rotating disks to examine the relationship
of natural frequencies, blade stiffness and nodal diameters to study how neighboring blades react upon each other and affect
blade natural frequency. With the use of elastic hinge theory and a cantilever beam model subjected to either a transverse
concentrated force or a bending moment at the free end, the force-deflection stiffness/moment-rotation stiffness of the beam
have been developed. Thereafter, the reaction forces and moments from the neighboring blades have been determined without
the need for an exact solution of large deformation of cantilever beams including geometrical nonlinearity effects. With the
use of the energy conservation principle and modal theory, the natural frequency of free transverse vibration of blades in
rotating disks has been determined for any nodal diameter. A comparison of the analytical and finite element solutions for
a bladed disk with uniform aerofoils shows that the analytical method presented in this paper is accurate. 相似文献
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This paper describes the problems concerning turbine rotor blade vibration that seriously impact the structural integrity of a developmental aero gas turbine. Experimental determination of vibration characteristics of rotor blades in an engine is very important from fatigue failure considerations. The blades under investigation are fabricated from nickel base super alloy through directionally solidified investment casting process. The blade surfaces are coated with platinum aluminide for oxidation protection. A three dimensional finite element modal analysis on a bladed disk was performed to know the likely blade resonances for a particular design in the speed range of operation. Experiments were conducted to assess vibration characteristics of bladed disk rotor during engine tests. Rotor blade vibrations were measured using non-intrusive stress measurement system, an indirect method of blade vibration measurement utilizing blade tip timing technique. Abnormalities observed in the vibration characteristics of the blade tip timing data measured during engine tests were used to detect the blade damage. Upon disassembly of the engine and subsequent fluorescent penetrant inspection, it was observed that three blades of the rotor assembly were identified to have damaged. These are the blades that exhibited vibration abnormalities as a result of large resonant vibration response while engine tests. Further, fractographic analysis performed on the blades revealed the mechanism of blade failures as fatigue related. The root cause of blade failure is established to be high cycle fatigue from the engine run data history although the blades were put into service for just 6 h of engine operation. 相似文献