外文翻译汽车变速器动态建模轮齿局部缺陷的早期检测.doc

河 北 农 业 大 学毕业论文外文资料翻译学 院：现代科技学院 专 　　业：农业机械化及其自动化0701班 姓 名：刘旭 学 号：2007614290123 外文出处: Power and Propulsion 附 件：1.外文原文；2.外文资料翻译译文完成日期：2011年5月9日 Dynamic Modeling of Vehicle Gearbox fox Early Detection of Localized Tooth DefectNagwa Ablhalim,Nabil Hammed,Magdy Abdel-hady,Shawki Abouel-Seoud and Eid S.Mohamed Helwan UniversityABSTRACT Dynamic modeling of the gear vibration is a useful tool to study the vibration response of a geared system under various gear parameters and operation conditions. An improved understanding of vibration signal is required for early detection of incipient gear failure to achieve high reliability. However, the aim of this work is to make use of a 6-degree-of-freedom gear dynamic model including localized tooth defect for early detection of gear failure. The model consists of a gear pair, two shafts, two inertias representing load and prime mover and bearings. The model incorporates the effects of time-varying mesh stiffness and damping, backlash, excitation due to gear errors and modifications. The results indicate that the simulated signal shows that as the defect size increases the amplitude of the acceleration signal shows that as the defect size increases the amplitude of the acceleration signal increases. The crest factor and kurtosis values of the simulated signal increase as the fault increases. Though the crest factor and kurtosis values give similar trends, kurtosis is a better indicator as compared to crest factor.KEYWORDS: Vibration acceleration, system modeling, Crest Factor, Kurtosis value, defect size, gear meshing, pinion, gearNOMENCLATUREJD,J1,J2,JL Drive motor, pinion, gear, and load mass moment of inertia replacement decision in a suitable time.m1,m2 Masses of pinion and gear.TD Driving motor torque.TL Load torque.TF1,TF2 Friction torque.C1,C2 Viscous damping coefficient of pinion and gear bearing.Cm Gear mesh damping.Km Gear mesh stiffness.K1,K2 Pinion and gear shaft stiffness.σ4 The variance square.N The number of samples.f The defect width in face direction.Kk Unit width Hertzian stiffness.θD, θ1,θ2,θL Angular displacement of driver motor, pinion, gear and load.θD, θ1,θ2,θL Angular velocity of drive motor, pinion, gear and load.θD, θ1,θ2,θL Angular acceleration of drive motor, pinion, gear and load.INTRODUCTION Much of the past research in the dynamic modeling area has concluded that an essential solution to the problem is to use a comprehensive computer modeling and simulation tool to aid the transmission design and experiments. These have been two major obstacles to such an approach:（1）Progress in understanding of the basic gear rattle phenomenon has been limited and slow. This is because the engine-clutch-transmission system involves some strong momlinearities including gear backlash, multi-valued springs, dry friction, hysteresis, and the like.（2）The gear rattle is a system problem and not only problem of gear teeth. Even through the research and industrial community has discussed the difficulties in varies stages of the problem, yet no thorough frame work covering the entire investigation process of such problem currently exists. This is largely due to the complexity of the power train system, which may make a computer analysis tool inefficient, in particularly when many different elements and clearances are encountered (e.g.,gears,bearings,splines,synchronizers,and clutch)[1-3]. A comprehensive review of mathematical models used in gear dynamics, published before 1986,has been presented by[4].In this review, gear dynamic models without defects have been discussed. In the past few years, researchers have been working on the gear dynamic models which include defects like pitting, spalling, crack and broken tooth. A single-degree-of-freedom model is used which include the effects of variable mesh stiffness, damping, gear errors, profile modifications and backlash. The effect of time-varying meshing damping is also included in this case. The solution is obtained by using the harmonic balance methods. A method of calculated the optimum profile modification has been proposed in order to obtain a zero vibration of the gear pair[5-7].They also proposed a linear approximate equation to mode the gear pair by using a single-degree-of freedom model. Gear rattle vibration is a undesirable vibration for passenger cars and light trucks equipped with manual transmissions. Un。