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Author: Steven James Martisauskas Publisher: ISBN: Category : Dynamics Languages : en Pages : 546
Book Description
Abstract: This thesis discusses a project to experimentally measure the dynamics of a multi- mesh gear system. Previous work on the design and testing of an idler gear system is detailed. Experimental results, specifically vibration modes of the test gearbox, correlate poorly with joint analytical modeling efforts. Limitations to the test setup, including high bearing drag and damping, result in questionable faith in experimental results. Disassembly of the test assembly results in anticipated damage to shaft and bearing components. Test gearbox components are repaired and modified, then re-assembled in a similar configuration. Results from testing on the newly modified gearbox are less limited by bearing drag and correlate well with previous results. The continued presence of high system damping leads to a critical analysis of modal extraction techniques. Agreement of experimental results between both assemblies of the test gearbox greatly increases faith in experimental results. Dynamic behavior including large amplitude parametric instabilities associated with mesh stiffness variation and nonlinear jump phenomena associated with tooth mesh contact loss are also experimentally demonstrated. Repeatability of this behavior is show to vary between various assemblies of the test gearbox.
Author: Steven James Martisauskas Publisher: ISBN: Category : Dynamics Languages : en Pages : 546
Book Description
Abstract: This thesis discusses a project to experimentally measure the dynamics of a multi- mesh gear system. Previous work on the design and testing of an idler gear system is detailed. Experimental results, specifically vibration modes of the test gearbox, correlate poorly with joint analytical modeling efforts. Limitations to the test setup, including high bearing drag and damping, result in questionable faith in experimental results. Disassembly of the test assembly results in anticipated damage to shaft and bearing components. Test gearbox components are repaired and modified, then re-assembled in a similar configuration. Results from testing on the newly modified gearbox are less limited by bearing drag and correlate well with previous results. The continued presence of high system damping leads to a critical analysis of modal extraction techniques. Agreement of experimental results between both assemblies of the test gearbox greatly increases faith in experimental results. Dynamic behavior including large amplitude parametric instabilities associated with mesh stiffness variation and nonlinear jump phenomena associated with tooth mesh contact loss are also experimentally demonstrated. Repeatability of this behavior is show to vary between various assemblies of the test gearbox.
Author: Andrew Mark Del Donno Publisher: ISBN: Category : Gearing Languages : en Pages : 269
Book Description
Abstract: This thesis presents a multi-faceted investigation into the dynamics of a three-gear idler gear train. Previous work and motivation for current research is discussed. Modifications to the physical test stand, new experimental procedures, and data acquisition software developments are detailed. Results for multiple phases of testing are given. Impact testing and shaker testing results on the complete system and isolated test gearbox are shown. Results from spinning system tests following bearing modifications are given along with a comparison to previous assemblies. Modal testing on the gearbox housing is shown as is the discovery of significant unexpected shaft bending behavior in the test gearbox shafts. Development of analytical models to incorporate additional degrees of freedom outside the gearbox is undertaken and correlation for the most recent test gearbox assembly is presented along with accepted system parameters.
Author: Tristan Martin Ericson Publisher: ISBN: Category : Languages : en Pages :
Book Description
Finally, spinning tests give the vibration response of each individual planetary gear component under operating conditions. The measured natural frequencies and vibration modes agree with the stationary modal vibration tests. The modes are separated into discrete categories, agreeing with the analytical literature. The effect of mean torque on vibration response is shown. Theoretical predictions of vibration suppression due to mesh phasing are compared against the experiments.
Author: Gang Liu Publisher: ISBN: Category : Gearing Languages : en Pages : 218
Book Description
Abstract: Multi-mesh gear systems are used in a variety of industrial machinery, where noise, quality, and reliability lie in gear vibration. The dynamic gear mesh forces are the source of vibration and result from parametric excitation and contact nonlinearity. The primary goal of this work is to develop mathematical models for multi-mesh gearsets with nonlinear, time-varying elements, to conduct numerical and analytical studies on nonlinear gear dynamic behaviors, such as parametric instabilities, frequency response, contact loss, and profile modification, and to provide guidelines for practical design and troubleshooting. First, a nonlinear analytical model considering dynamic load distribution between individual gear teeth is proposed, including the influence of variable mesh stiffnesses, profile modifications, and contact loss. This model yields better agreement than two existing models when compared against nonlinear gear dynamics from a finite element benchmark. Perturbation analysis finds approximate frequency response solutions for providing guidance for optimizing system parameters. The closed-form solution is validated by numerical integration. Second, the nonlinear, parametrically excited dynamics of idler and counter-shaft gear systems are examined. The periodic steady state solutions are obtained using analytical and numerical approaches. With proper stipulations, the contact loss function and the variable mesh stiffness are reformulated into a form suitable for perturbation. The closed-form solutions from perturbation analysis expose the impact of key parameters on the nonlinear response. The analysis for this strongly nonlinear system compares well to separate harmonic balance/continuation and numerical integration solutions. Finally, this work studies the influences of tooth friction on parametric instabilities and dynamic response of a single-mesh gear pair. A mechanism whereby tooth friction causes gear tooth bending is shown to significantly impact the dynamic response. A dynamic model is developed to consider this mechanism together with the other contributions of tooth friction and mesh stiffness fluctuation. Perturbation analysis finds approximate solutions that predict and explain the parametric instabilities. The effects of time-varying friction moments about the gear centers and friction-induced tooth bending are critical to parametric instabilities and dynamic response. The impacts of friction coefficient, bending effect, contact ratio, and modal damping on the stability boundaries are revealed.
Author: Publisher: ISBN: Category : Languages : en Pages : 30
Book Description
Modification of geometry of spur and helical gears with parallel axes and helical gears with crossed axes is proposed. The finishing process of gear generation is shaving. The purposes of modification of the gear geometry are to localize and stabilize the bearing contact, and to reduce noise and vibration. The goals mentioned above are achieved by using profile crowning and plunging the shaver by a prescribed motion during pinion generation. The pinion becomes double crowned. The gear member is generated as a conventional involute gear. A tooth contact analysis (TCA) program for simulation of meshing and contact was developed and the analysis is illustrated with TCA results for spur and helical gears.
Author: Publisher: ISBN: Category : Languages : en Pages : 128
Book Description
Planetary gear noise and vibration are primary concerns in their applications in helicopters, automobiles, aircraft engines, heavy machinery, and marine vehicles. Dynamic analysis is essential to the noise and vibration reduction. This work analytically investigates some critical issues and advances the understanding of planetary gear dynamics. A lumped-parameter model is built for the dynamic analysis of general planetary gears. The unique properties of the natural frequency spectra and vibration modes are rigorously characterized. These special structures apply for general planetary gears with cyclic symmetry and, in practically important case, systems with diametrically opposed planets. The special vibration properties are useful for subsequent research. Taking advantage of the derived modal properties, the natural frequency and vibration mode sensitivities to design parameters are investigated. The key parameters include mesh stiffnesses, support/bearing stiffnesses, component masses, moments of inertia, and operating speed. The eigensensitivities are expressed in simple, closed-form formulae associated with modal strain and kinetic energies. As disorders (e.g., mesh stiffness variation, manufacturing and assembling errors) disturb the cyclic symmetry of planetary gears. their effects on the free vibration properties are quantitatively examined. Well-defined veering rules are derived to identify dramatic changes of natural frequencies and vibration modes under parameter variations. The knowledge of free vibration properties, eigensensitivities and veering rules provide important information to effectively tune the natural frequencies and optimize structural design to minimize noise and vibration. Parametric instabilities excited by mesh stiffness variations are analytically studied for multi-mesh gear systems. The discrepancies of previous studies on parametric instability of two-stage gear chains are clarified using perturbation and numerical methods.
Author: Steven James Martisauskas
Author: Steven James Martisauskas
Author: Andrew Mark Del Donno
Author: Daniel Roy Kiracofe
Author: Tristan Martin Ericson
Author: 
Author: United States. National Aeronautics and Space Administration
Author: Gang Liu
Author: 
Author: Fred K. Choy
Author: