Master of Science, The Ohio State University, 2020, Mechanical Engineering

In this study, an experimental investigation on the influence of tensile mean stress on gear tooth bending fatigue life is performed. A newly developed single-tooth bending test machine is utilized to perform gear tooth bending fatigue experiments under various loading conditions. A new single-tooth bending test fixture is developed for a chosen test gear. A detailed experimental methodology is presented on dynamic and static strain measurements of the chosen test gear root fillet profile in order to (i) quantify any dynamic loading effects at high loading frequencies, and (ii) validate maximum root stress predictions. Two sets of fatigue tests are performed at load levels of R = 0.05 and R = 0.5 whose results are analyzed statistically to generate L50 and L10 curves for each loading case. Utilizing the L50 stress-life curves, a map of constant life is obtained, showing a straight-line relationships between mean stress and alternating stress. It is shown that an increase in the tensile mean stress reduces the fatigue lives of gear teeth.

Committee: Ahmet Kahraman Dr. (Advisor); Talbot David Dr. (Committee Member) Subjects: Engineering; Materials Science; Mechanical Engineering; Statistics

Master of Science, The Ohio State University, 2019, Mechanical Engineering

Noise and vibration performance of a gear system is critical in any industry. Vibrations caused by the excitations at the gear meshes propagate to the transmission housing to cause noise, while also increasing gear tooth stresses to degrade durability. As such, gear engineers must seek gear designs that are nominally quiet with low vibration amplitudes. They must also ensure that this nominal performance is robust in the presence of various manufacturing errors. This thesis research aims at an experimental investigation of the influence of one type of manufacturing error, namely random tooth spacing errors, on the vibratory responses of spur and helical gear pairs. For this purpose, families of spur and helical gear test specimens having intentionally induced, tightly controlled random spacing error sequences are fabricated. These specimens are paired and assembled in various ways to achieve different sequences of composite spacing errors. Static and dynamic motion transmission error measurements from these tests are compared to the baseline case of “no error” gear to quantify the impact of random spacing errors on the dynamic response. These comparisons show that there is a significant, quantifiable impact of random spacing errors on both spur and helical gear dynamics. In general, vibration amplitudes of gear pairs having random spacing errors are higher than those of the corresponding no-error gear pairs. In the frequency domain, gears having random spacing errors exhibit broad-band spectra with significant non-mesh harmonics, pointing to potential noise quality issues.

Committee: Ahmet Kahraman (Advisor); David Talbot (Committee Member) Subjects: Engineering; Mechanical Engineering

Master of Science, The Ohio State University, 2018, Mechanical Engineering

In this study, a two-dimensional model is proposed for determining theoretical contact lines, tooth separation, and approximated loaded transmission error with frequency spectra thereof, as well as various other output variables such as instantaneous center distance, operating pressure angle, and instantaneous contact ratio when circular runout error is applied to either or both gears in a spur or helical gear pair. As an addendum, a method for calculating off-line of action tooth separation using this model is described for spur gears. Additionally, a three-dimensional model is proposed for determining theoretical contact lines and tooth separation when any combination of circular runout or wobble error are applied to either or both gears in a spur or helical gear pair. Sample analyses are shown for spur and helical gear pairs with runout error applied using the two-dimensional model, and a helical gear pair with various combinations of runout and wobble error applied using the three-dimensional model. The results are discussed qualitatively with respect to the expected effects the applied errors would have on the tooth separation and related variables.

Committee: David Talbot (Advisor); Ahmet Kahraman (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2011, Mechanical Engineering

In this study, an experimental investigation is performed to investigate the impact of various gear errors on transmission error and root fillet stresses. A test set-up is devised to operate a pair of spur gears under loaded, low-speed conditions. Two measurement systems; one an optical encoder-based transmission error measurement system and the other a multi-channel strain measurement system, are developed and implemented with the test set-up. A set of test gears having various types and tightly-controlled magnitudes of manufacturing errors are designed and procured. These errors include indexing errors of different tooth sequences, pitch line run-out errors and lead wobble errors. An extensive test matrix is executed to quantify the impact of these errors on the loaded static transmission error and the root stresses of the spur gears. At the end, the same test conditions are simulated by using a recent feature of gear analysis model (LDP) to assess the accuracy of its predictions.

Committee: Ahmet Kahraman PhD (Advisor); Donald Houser PhD (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2008, Mechanical Engineering

This study examines the salient effects of sliding friction on spur and helical gear dynamics and associated vibro-acoustic sources. First, new dynamic formulations are developed for spur and helical gear pairs based on a periodic description of the contact point and realistic mesh stiffness. Difficulty encountered in existing discontinuous models is overcome by characterizing a smoother transition during the contact. Frictional forces and moments now appear as either excitations or periodically-varying parameters, since the frictional force changes direction at the pitch point/line. These result in a class of periodic ordinary differential equations with multiple and interacting coefficients. Predictions match well with a benchmark finite element/contact mechanics code and/or experiments. Second, new analytical solutions are constructed which provide an efficient evaluation of the frictional effect and a more plausible explanation of dynamic interactions in multiple directions. Both single- and multi-term harmonic balance methods are utilized to predict dynamic mesh loads, friction forces and pinion/gear displacements. Such semi-analytical solutions explain the presence of higher harmonics in gear noise and vibration due to exponential modulations of periodic parameters. This knowledge also analytically reveals the effect of the tooth profile modification in spur gears under the influence of sliding friction. Further, the Floquet theory is applied to obtain closed-form solutions of the dynamic response for a helical gear pair, where the frictional effect is quantified by an effective piecewise stiffness function. Analytical predictions are validated using numerical simulations. Third, an improved source-path-receiver vibro-acoustic model is developed to quantify the effect of sliding friction on structure-borne noise. Interfacial bearing forces are predicted for the spur gear source sub-system given two whine excitations (static transmission error and sliding frict (open full item for complete abstract)

Committee: Rajendra Singh (Advisor) Subjects: Engineering, Mechanical

Master of Science in Mechanical Engineering (MSME), Wright State University, 2021, Mechanical Engineering

This study describes contact fatigue behavior of spur gear contacts operating under mixed elastohydrodynamic condition. The focus is placed on the starvation effect on fatigue crack initiation. With the model, parametric simulations are carried out with different contact parameters. In the process, the lubricant supply is varied to alter the lubrication condition from fully flooded to severely starved circumstance. Multi-axial stress fields induced by surface normal and tangential tractions are evaluated, whose amplitudes and means are used in a multi-axial fatigue criterion to determine the crack initiation life. It is found a lower lubricant viscosity elongates fatigue life when severe starvation occurs, which is opposite to the EHL rule under fully flooded lubrication condition. However, it's in line with the experimental observation [1], where film thickness was shown to increase when moving from high viscosity base oil to a lower one under starvation condition.

Committee: Sheng Li Ph.D. (Advisor); Ahsan Mian Ph.D. (Committee Member); Joy Gockel Ph.D. (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2021, Mechanical Engineering

Nonlinear dynamic behavior of a spur gear pair has been a major topic in both gear dynamics and nonlinear vibration fields. A spur gear pair can exhibit a wide range of nonlinear behavior primarily due to its backlash and periodically time-varying mesh stiffness. While a number of theoretical studies pointed to the possibility of severe subharmonic resonances at integer multiples of the primary resonance of the gear pair, past experimental investigations focused overwhelmingly on the behavior within the speed ranges where primary and super-harmonic resonance peaks occur. There has been very little experimental evidence of such subharmonic resonances, perhaps because such investigations require very high-speed experiments pushing the limits of test machine and measurement system capabilities. In this study, a test gear pair design is implemented to reduce the primary resonance frequency significantly such that the first three subharmonic resonances can be studied using an existing test machine and a conventional gear transmission error measurement method. Transient and steady-state data are collected at different transmitted torque values to show softening type of nonlinear behavior at super-harmonic and primary resonance peaks along with a well-defined first subharmonic resonance peak dictated by period-2 motions. Other subharmonic motions up to period-4 are also demonstrated experimentally. At the end, two different dynamic models, a discrete torsional model and a deformable-body model, are employed to simulate the experiments, focusing on the subharmonic resonance regions. Both models are shown to be effective in correlating to experiments.

Committee: Ahmet Kahraman (Advisor); David Talbot (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2021, Mechanical Engineering

The design of a gearbox is subject to multiple performance requirements that must be met. One such requirement is power density, a metric defined as power transmitted per gear volume or per weight. In aerospace applications, one method of reducing gearbox weight to increase power density has been removing material from gear blanks through the use of thin webs. This study adapts a representative spur gear pair design to investigate the effects of using thin-web gears. A deformable-body model of the gear pair is developed to perform quasi-static and dynamic analyses of the gear pair variations with solid and thin webs, subjected to errors causing the load distribution to skew axially. Under quasi-static conditions, the flexible web deflections are shown to ease some of the adverse effects of gear errors. To determine the dynamic conditions where flexible rim modes could be a factor, impact tests are performed along with a modal analysis using the model. The contributions of these rim modes to the overall dynamic behavior are shown to be modest.

Committee: Ahmet Kahraman PhD (Advisor); David Talbot PhD (Committee Member) Subjects: Engineering; Mechanical Engineering

Master of Science in Mechanical Engineering (MSME), Wright State University, 2019, Mechanical Engineering

Pitting is a rolling contact fatigue phenomenon commonly observed in mechanical rolling elements, such as gears and bearings. In case of gear contacts, pitting usually takes place in the dedendum region, where both sliding and contact load are high. In this study, a model is developed to predict surface breaking crack formation fatigue lives, including both nucleation and propagation stages, for spur gear contacts operating under mixed elastohydrodynamic lubrication (EHL) condition. The model utilizes a gear load distribution model for tooth contact Analysis. A mixed EHL formulation is implemented to evaluate the surface normal pressure and tangential shear, incorporating the lubricant non-Newtonian behavior, which is influential on lubrication film thickness and surface tractions under high sliding condition. According to the surface tractions, a boundary element formulation is utilized to determine the stress fields, whose contribution to fatigue damage accumulation is assessed using a multi-axial fatigue criterion, predicting the crack nucleation life. As for the crack propagation life evaluation, the Paris and Erdogan's formula is adopted. With the developed contact fatigue model, a parametric investigation is performed considering a spur gear pair, operating under different loads and different surface roughness conditions.

Committee: Sheng Li Ph.D. (Advisor); Ahsan Mian Ph.D. (Committee Member); Joy Elizabeth Gockel Ph.D. (Committee Member) Subjects: Mechanical Engineering

Master of Science in Mechanical Engineering (MSME), Wright State University, 2019, Mechanical Engineering

Lubrication is provided to the gear trains in automotive and aerospace transmission systems to prevent mechanical contact through the formation of a full lubricant film, which in turn removes heat generated at the gear contact surfaces. When debris blocks the inlet nozzle, the flow of lubricant is restricted and mechanical components experience lubrication starvation. Under starved lubrication the temperatures of the contact surfaces become elevated which can lead to the formation of a weld between them, a catastrophic failure mode called scuffing. For spur gears, the occurrence of scuffing is due to high sliding in the vicinity of the root or tip, where the shear thinning effect decreases the lubrication film thickness. This lubricant depletion increases the contact pressure and frictional heat flux beyond a critical limit, resulting in weld formation. The weld is immediately torn apart by the continuous relative motion of the components, causing extreme damage to the tooth surfaces. The objective of this study is to characterize the tribological behavior of high sliding gear contacts under starved lubrication. This is achieved through numerical flow simulations which utilize a generalized Reynolds equation with a non-Newtonian flow coefficient, and incorporate the dependence of lubricant viscosity on pressure and temperature. In order to study the effects of lubrication starvation a film fraction parameter is used in the Reynolds equation, removing the need for measured or assumed inlet lubrication geometry. This work presents a parametric study of engineering surface profiles under different operating conditions to show an asymptotic relationship between flash temperature and the severity of the lubrication starvation, supported by an analysis of pressure, film fraction parameter, friction coefficient, and power loss. The results of these investigations justify further numerical and experimental studies of scuffing failure for gear contacts.

Committee: Sheng Li Ph.D. (Advisor); Harok Bae Ph.D. (Committee Member); Ahsan Mian Ph.D. (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2019, Mechanical Engineering

This study was conducted to evaluate the effect of surface finish on spur gear power losses under jet lubrication. Four different surface finish combinations were tested: (i) hard ground surface pair, (ii) chemically polished surface pair, (iii) super honed surface pair and (iv) hard ground against chemically polished surface pair. The test was conducted at 432 different operating condition combinations of speed, torque, lubricant type and inlet temperature. An FZG back-to-back set up was used to conduct the test. Surface roughness inspections were carried out at regular intervals to monitor any changes in surface roughness characteristics. The measured power losses were resolved into spin (load independent) and mechanical (load dependent) power losses. The relation between both losses and various operating conditions were explored. As expected, spin power loss did not vary with variation in surface finish. Mechanical power loss increased with increase in speed and torque. Various surface roughness and operating parameters such as BAC curves and lambda ratio were calculated for each surface finish combination to study their correlation to power losses measured. For smoother surfaces, an increase in temperature decreased power loss as the viscosity of the lubricant decreased and hence rolling friction losses dominating the mechanical power loss decreased. However, for rougher surfaces sliding friction losses seemed to be dominant due to high amounts of asperity contact. Thus, more cases of higher power loss at high temperatures were observed for rougher surfaces.

Committee: David Talbot Dr. (Advisor) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2017, Mechanical Engineering

This paper complements recent investigations [Handschuh et al. (2014), Talbot et al. (2016)] of the influences of tooth indexing errors on dynamic factors of spur gears by presenting data on changes to the dynamic transmission error. An experimental study is performed using an accelerometer-based dynamic transmission error measurement system incorporated into a high-speed gear tester to establish baseline dynamic behavior of gears having negligible indexing errors, and to characterize changes to this baseline due to application of tightly-controlled intentional indexing errors. Spur gears having different forms of indexing errors are paired with a gear having negligible indexing error. Dynamic transmission error of gear pairs under these error conditions is measured and examined in both time and frequency domains to quantify the transient effects induced by these indexing errors. These measurements are then compared against the baseline, no error condition, as a means to quantify the dynamic vibratory behavior induced due to the tooth indexing errors. These comparisons between measurements indicate clearly that the baseline dynamic response, dominated by well-defined resonance peaks and mesh harmonics, are complemented by non-mesh orders of transmission error due the transient behavior induced by indexing errors. In addition, the tooth (or teeth) having indexing error imparts transient effects which dominate the vibratory response of the system for significantly more mesh cycles than the teeth having errors are in contact. For this reason, along with the results presented in Talbot et al. (2016), it was concluded that spur gears containing indexing errors exhibit significant deviations from nominal behavior, at both a system and time-domain level.

Committee: Ahmet Kahraman (Advisor); David Talbor (Committee Member) Subjects: Engineering; Mechanical Engineering

Master of Science, The Ohio State University, 2016, Mechanical Engineering

An experimental investigation of spur gear efficiency is conducted under various jet-lubricated and dip-lubricated conditions. A test methodology is developed to measure load-independent (spin) and load-dependent (mechanical) losses to a gearbox containing a single spur gear pair. An experimental test matrix is defined to study the influence that the lubrication method has on these losses. The test matrix includes two dip-lubricated conditions that vary in submersion level of the gear pair, and four jet-lubricated conditions that vary in the gear mesh target location and velocity of the oil. Results indicate that the spin power losses are impacted by the lubrication method significantly while the mechanical losses are not influenced. An investigation of spur gear contact fatigue is conducted under several lubrication schemes from the efficiency study. A test methodology is developed to evaluate variations in tooth geometry due to surface wear, roughness, and pitting life. Pitting lives under each lubrication method are analyzed statistically to quantify any meaningful differences in gear pitting life. Results indicate that contact fatigue lives from jet-lubricated tests are as high as dip-lubricated ones as long as jet velocities are sufficient.

Committee: Ahmet Kahraman Dr. (Advisor); Brian Harper Dr. (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2011, Mechanical Engineering

In this study, the influence of different gear steels on the contact fatigue life of ground spur gear pairs was investigated. The three gear steels considered in the study were (i) AISI 8620, (ii) AISI 4620M, and (iii) AISI 5120M. Batches of gears made out of these three materials using the same finishing process at about the same roughness and hardness levels were used in these tests. Each specimen was qualified for its dimensional accuracy, hardness and surface roughness amplitudes before being tested on standard, FZG type, four-square test machines according to well-defined procedures and failure criteria. Interim inspections throughout each test were used to describe the mechanisms leading to pitting failures. The pitting data obtained for each gear material were tabulated and analyzed statistically whenever possible. The pitting fatigue life results of ground gears made of these materials were compared to each other as well as to baseline shaved gear and super-finished gear data obtained in previous related studies. The results indicated that hard grinding gears increases the pitting life of spur gears substantially in comparison to a baseline of shaved gears. Ground gears were also shown to provide improvements in the same order as super-finished gears.

Committee: Ahmet Kahraman PhD (Advisor); Donald Houser PhD (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2010, Mechanical Engineering

This work aims at developing linear mathematical models of single-mesh spur and helical gears mounted on compliant parallel shafts, and single span of a serpentine belt with pulleys also mounted on parallel compliant shafts. Both the geared shaft models are hybrid discrete-continuous ones where the gears modeled as rigid disks along with the mesh spring form the discrete elements while the elastic shafts having transverse as well as torsional flexibility constitute the continuous elements. The non-dimensional governing equations along with the natural boundary conditions are developed using the Hamilton's principle. The governing equations of the flexural and torsional shafts vibrations and the equations of motion of the disks are written in an extended operator form to prove the self-adjointness of the system. The assumed modes method is used to discretize the system equations where the matching conditions are incorporated with the use of Lagrange multipliers. Orthonormal global basis functions for flexure and torsion are chosen from separate families forming complete sets. The sensitivities of the natural frequencies of different modes to mesh stiffness, torsional and flexural rigidities of the shafts, and lengths of the shafts are examined and the results are correlated with the modal energy distributions. Excitation in the form of the loaded static transmission error at the gear mesh is identified and converted to the discretized form and the response for the same is calculated. Torsional spring at the gear mesh in the helical gear-shaft model accounts for the energy stored due to the relative tilting of the gears. The rotation speed is high and therefore, the gyroscopic effect is non-negligible. Hamilton's principle is used to obtain the non-dimensional governing equations and the equations of motion of the disks. Excitation in the form of the loaded static transmission error at the gear mesh is incorporated in the equations of motion. The extended operator fo (open full item for complete abstract)

Committee: Prof. Rama Yedavalli PhD (Advisor); Prof. Daniel Mendelsohn PhD (Advisor); Prof. Ahmet Kahraman PhD (Committee Member); Prof. Gary Kinzel PhD (Committee Member) Subjects: Engineering

Master of Science, The Ohio State University, 2009, Mechanical Engineering

This study consists of experimental studies involving two modes of gear contact fatigue failure: gear pitting (spalling) and gear scuffing. For pitting studies, several materials and surface treatments were investigated at various stress levels. These surface treatments included (i) hobbed and shaved (baseline), (ii) chemically polished, (iii) shot peened and plastic honed, and (iv) ground gears. Pitting fatigue lives of chemically polished gears were greater than those of baseline specimens. Both shot peened and plastic honed gears and ground gears were shown to have greater pitting fatigue lives than baseline gears. The improved pitting fatigue life of ground gears over baseline gears appears related to the improved involute profile shapes of the specimens.For gear scuffing experiments, the standard ISO 14635-1 FZG Scuffing Test was performed on AISI 8620 type A spur gears. These experiments included four uncoated gear pairs and one gear pair coated with an experimental PVD coating. Uncoated gears encountered scuffing during Stages 11 and 12. A high correlation between temperature and scuffing results was detected for both coated and uncoated specimens.

Committee: Ahmet Kahraman PhD (Advisor); Donald Houser PhD (Committee Member) Subjects: Mechanical Engineering

Master of Science in Mechanical Engineering, Cleveland State University, 2012, Fenn College of Engineering

A Finite Element procedure has been developed in this work to determine the load distribution factor, Km, of the AGMA formula for a set of spur gear. At first, a spur gear with perfect involute is modeled using a 3-D CAD software. The model is them is assembled with shafts having 1, 2, and 3 degree misalignments. The generated 3-D models were in turn imported to ANSYS workbench to calculate the maximum bending and contact stresses using finite element method. The results generated were then compared with the maximum bending stress results obtained for parallel shafts to estimate the Load Distribution Factor Km. This study resulted in Km values of 1.03,1.11, and 1.14.

Committee: Majid Rashidi PhD (Committee Chair); Rama S R Gorla PhD (Committee Member); Asuquo Ebiana PhD (Committee Chair) Subjects: Mechanical Engineering

Master of Science, University of Akron, 2008, Mechanical Engineering

Developing an analytical approach and modeling procedure to evaluate stress distribution and quenching process under velocity and moment would provide a useful tool to improve spur gear design with high efficiency and low cost. Based on the theories of gear engagement, contact analysis and friction, a three dimensional finite element model of the spur gear system was established to investigate stress distribution and analyze the advantage of quenching process. A full-scale deformable-body model and a simplified discrete model were both shown to be accurate through extensive comparisons to the theoretical database generated in this study. The major work is summarized as follows. Applying Finite Element Method, contact stress analysis of meshing spur gears was conducted. Applying the relation equation in Pro/Engineer, an accurate three dimensional spur gear model was developed. This model can be used to analyze many similar spur gears for design optimization. Three dimensional finite element models of spur gear system were established to investigate stress distributions over operating speeds with consideration of lubrication conditions. The three-dimensional FEA program developed can be a useful tool in investigating design parameters for spur gears. A theoretical finite element model of spur gear system was developed. The research result shows that the theoretical methods presented in this thesis have good simulation accuracy. This method could also be applied to many other engineering problems. Finite Element simulation of spur gear was developed and used to predict distributions of stress and other material properties. Thermo-elastic-plastic constitutive equation coupled with the mechanical strain, thermal strain, phase transformation strain, and transformation induced plasticity is described in detail. The quenching result in the simulation proved the theory and ensured product quality.

Committee: Lin Yueh-Jaw (Advisor) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2013, Mechanical Engineering

In this study, theoretical and experimental investigations of the effect of tooth spacing errors on the motion transmission error and root stresses of spur gear pairs are performed. A test setup with dedicated instrumentation for the measurement of the static transmission error and root stresses is devised. A number of experiments are performed with gears having deterministic spacing errors (at one or two teeth only) and random spacing errors (all teeth having a random distribution of errors as in a typical production gear). A test matrix defined by a range of torque at a very low speed is executed with each error configuration to experimentally quantify the influence of spacing errors on the static transmission error and the gear tooth root stresses. The results of these experiments form an extensive database on the impact of spacing errors on the static transmission error (a typical noise metric) and the root stresses (a durability metric). These experiments are simulated by using two existing gear contact models to demonstrate their accuracy and describe the empirical trends physically. A methodology is proposed at the end to relate increases in root stresses to the spacing error magnitudes directly. Closed-form expressions resulting from this methodology allow determination of the stress amplification factors due to a certain range of spacing error tolerances as well as quantifying how much spacing error can be tolerated within a user defined stress limit.

Committee: Ahmet Kahraman Ph.D (Advisor); Noriko Katsube Ph.D (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2013, Mechanical Engineering

In this study, load-independent (spin) power losses of a gearbox operating under dip-lubrication conditions are investigated experimentally. A family of final drive helical gear pairs from an automotive transmission is considered as the example for this investigation. A dedicated gearbox is designed and fabricated to operate a single gear or a gear pair under given speed conditions. The test gearbox is incorporated with a high-speed test bed with power loss measurement capability. A test matrix that consists of sets of tests with (i) single spur, helical gears, or disks with no teeth, and (ii) helical gear pairs of varying gear ratios is executed with three different transmission fluids at various temperatures and immersion depths. Power losses from single gear and gear pair tests at identical operating conditions are compared to break down the total spin loss to its main components, namely gear drag loss, gear mesh pocketing loss, and bearing/seal loss. In addition, the space around the gears within the gearbox will be altered to quantify any influences of enclosures and peripheral shrouds on the spin losses of a rotating gear.

Committee: Ahmet Kahraman Dr. (Advisor); Donald Houser Dr. (Committee Member) Subjects: Mechanical Engineering