Power Transmission Efficiencies and Friction Coefficients at Teeth of Novikov-Wildhaber and Involute Gears

1985 ◽  
Vol 107 (1) ◽  
pp. 74-81 ◽  
Author(s):  
A. Ishibashi ◽  
H. Yoshino
Keyword(s):  
Power Transmission ◽  
Gear Ratio ◽  
Experimental Results ◽  
New Techniques ◽  
Friction Coefficients ◽  
Cylindrical Gears ◽  
High Speeds ◽  
Involute Gears ◽  
Low Speeds ◽  
The Difference

New equations have been derived to calculate the power transmission efficiencies, at the meshing teeth, of two kinds of representative cylindrical gears, Novikov-Wildhaber and involute gears. The efficiencies could be calculated from the equations and the friction coefficients obtained by simple experiments with test rollers. In order to show clearly the difference in the power transmission efficiencies of the two kinds of gears, the authors designed and made two interesting gear pairs with a small number of pinion teeth (Z1 = 3) and with a high gear ratio (Z2/Z1 = 9) by applying new techniques developed by them. The effects of gear speed, tooth load, type of lubricant, etc. upon the power transmission efficiencies were clarified using two interesting techniques to measure the efficiency. The experimental results indicated that the efficiency of the Novikov-Wildhaber gears was appreciably higher at high speeds, while it was lower than the involute gears at the start of rotation and also at low speeds.

Cylindrical Gears with Increased Contact Area – Proposal of Application in Watercrafts Power Transmission Systems

2015 ◽  
Vol 236 ◽  
pp. 26-30 ◽  
Author(s):  
Michał Batsch ◽  
Tadeusz Markowski ◽  
Wojciech Homik
Keyword(s):  
Power Transmission ◽  
Point Contact ◽  
Surface Strength ◽  
Hertz Theory ◽  
Cylindrical Gears ◽  
Position Errors ◽  
Power Transmission Systems ◽  
Involute Gears ◽  
Maximum Contact ◽  
Two Bodies

Paper presents the method for obtaining maximum contact pressure of Novikov gears. Described surface strength calculation method is based on Hertz theory of two bodies being in point contact. What’s more the influence of gear position errors on maximum contact stresses has been presented. Also the comparison of Hertz stresses for Novikov and involute gears has been made.

scholarly journals Image Structure-Preserving Denoising Based on Difference Curvature Driven Fractional Nonlinear Diffusion

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Xuehui Yin ◽  
Shangbo Zhou
Keyword(s):  
Fractional Order ◽  
Anisotropic Diffusion ◽  
Noise Removal ◽  
Experimental Results ◽  
New Techniques ◽  
Proposed Model ◽  
Staircase Effect ◽  
The Difference ◽  
Curvature Driven ◽  
Difference Curvature

The traditional integer-order partial differential equations and gradient regularization based image denoising techniques often suffer from staircase effect, speckle artifacts, and the loss of image contrast and texture details. To address these issues, in this paper, a difference curvature driven fractional anisotropic diffusion for image noise removal is presented, which uses two new techniques, fractional calculus and difference curvature, to describe the intensity variations in images. The fractional-order derivatives information of an image can deal well with the textures of the image and achieve a good tradeoff between eliminating speckle artifacts and restraining staircase effect. The difference curvature constructed by the second order derivatives along the direction of gradient of an image and perpendicular to the gradient can effectively distinguish between ramps and edges. Fourier transform technique is also proposed to compute the fractional-order derivative. Experimental results demonstrate that the proposed denoising model can avoid speckle artifacts and staircase effect and preserve important features such as curvy edges, straight edges, ramps, corners, and textures. They are obviously superior to those of traditional integral based methods. The experimental results also reveal that our proposed model yields a good visual effect and better values of MSSIM and PSNR.

scholarly journals The Influence of the Bearing Lifetime on the Performance of Universal Gear Drives with High Gear Ratio Values

2019 ◽  
Vol 287 ◽  
pp. 01022
Author(s):  
Milan Rackov ◽  
Siniša Kuzmanović ◽  
Ivan Knežević ◽  
Maja Čavić ◽  
Marko Penčić ◽  
...  
Keyword(s):  
Load Capacity ◽  
Gear Ratio ◽  
Output Shaft ◽  
Operating Life ◽  
Gear Drive ◽  
High Speeds ◽  
Low Speeds ◽  
Gear Drives

The problem of defining the load (nominal torque on the output shaft - T2N) of universal gear drives depending on the size of the gear ratio is analysed in this paper. It is logical that the load capacity of gear drive depends on the weakest gear component. Since the gears are the most expensive components of gear unit, it tends to maximize their performance. However, for low gear ratio, i.e. for high speeds, the bearings often limit their load capacity since the same bearings are used in all transmission ratios because it is not practiced to oversize the bearings at low speeds. Nowadays, when high values of gear ratio are used, it is interesting to consider the dependence of the nominal torque at the output regarding to gear ratio and operating life of the unit.

scholarly journals A Collision Dynamics Model of a Multi-Level Train

2006 ◽  
Author(s):  
Michelle Priante ◽  
David Tyrell ◽  
Benjamin Perlman
Keyword(s):  
Three Dimensional ◽  
Design Parameters ◽  
Collision Dynamics ◽  
Dynamics Model ◽  
Single Level ◽  
High Speeds ◽  
Front End ◽  
Multi Level ◽  
Low Speeds ◽  
Vertical Accelerations

In train collisions, multi-level rail passenger vehicles can deform in modes that are different from the behavior of single level cars. The deformation in single level cars usually occurs at the front end during a collision. In one particular incident, a cab car buckled laterally near the back end of the car. The buckling of the car caused both lateral and vertical accelerations, which led to unanticipated injuries to the occupants. A three-dimensional collision dynamics model of a multi-level passenger train has been developed to study the influence of multi-level design parameters and possible train configuration variations on the reactions of a multi-level car in a collision. This model can run multiple scenarios of a train collision. This paper investigates two hypotheses that could account for the unexpected mode of deformation. The first hypothesis emphasizes the non-symmetric resistance of a multi-level car to longitudinal loads. The structure is irregular since the stairwells, supports for tanks, and draglinks vary from side to side and end to end. Since one side is less strong, that side can crush more during a collision. The second hypothesis uses characteristics that are nearly symmetric on each side. Initial imperfections in train geometry induce eccentric loads on the vehicles. For both hypotheses, the deformation modes depend on the closing speed of the collision. When the characteristics are non-symmetric, and the load is applied in-line, two modes of deformation are seen. At low speeds, the couplers crush, and the cars saw-tooth buckle. At high speeds, the front end of the cab car crushes, and the cars remain in-line. If an offset load is applied, the back stairwell of the first coach car crushes unevenly, and the cars saw-tooth buckle. For the second hypothesis, the characteristics are symmetric. At low speeds, the couplers crush, and the cars remain in-line. At higher speeds, the front end crushes, and the cars remain in-line. If an offset load is applied to a car with symmetric characteristics, the cars will saw-tooth buckle.

Dynamical theory of neutron diffraction

1978 ◽  
Vol 56 (10) ◽  
pp. 1261-1288 ◽  
Author(s):  
V. F. Sears
Keyword(s):  
Neutron Diffraction ◽  
Theoretical Basis ◽  
Dynamical Theory ◽  
Experimental Results ◽  
Neutron Interferometry ◽  
New Techniques ◽  
The Past ◽  
Neutron Optics ◽  
Coherent Wave ◽  
Special Cases

We present a review of the dynamical theory of neutron diffraction by macroscopic bodies which provides the theoretical basis for the study of neutron optics. We consider both the theory of dispersion, in which it is shown that the coherent wave in the medium satisfies a macroscopic one-body Schrödinger equation, and the theory of reflection, refraction, and diffraction in which the above equation is solved for a number of special cases of interest. The theory is illustrated with the help of experimental results obtained over the past 10 years by a number of new techniques such as neutron gravity refractometry, Pendellösung interference, and neutron interferometry.

Simulation and experimentation of a magnetorheological brake with adjustable gap

2016 ◽  
Vol 28 (12) ◽  
pp. 1614-1626 ◽  
Author(s):  
Wan-Li Song ◽  
Dong-Heng Li ◽  
Yan Tao ◽  
Na Wang ◽  
Shi-Chao Xiu
Keyword(s):  
Magnetorheological Fluid ◽  
Structure Design ◽  
Experimental Results ◽  
Wear Property ◽  
Braking Performance ◽  
Braking Torque ◽  
The Difference ◽  
The Impact ◽  
Theoretical Analyses ◽  
Magnetostatic Simulation

The aim of this work is to investigate the effect of the small magnetorheological fluid gap on the braking performance of the magnetorheological brake. In this article, theoretical analyses of the output torque are given first, and then the operating principle and design details of the magnetorheological brake whose magnetorheological fluid gap can be altered are presented and discussed. Next, the magnetic circuit of the proposed magnetorheological brake is conducted and further followed by a magnetostatic simulation of the magnetorheological brakes with different sizes of fluid gap. A prototype of the magnetorheological brake is fabricated and a series of tests are carried out to evaluate the braking performance and torque stability, as well as the verification of the simulation results. Experimental results show that the braking torque increases with the increase in the current, and the difference for the impact of the fluid gap on braking performance is huge under different currents. The rules, which the experimental results show, have an important significance on both the improvement of structure design for magnetorheological brake and the investigation of the wear property under different fluid gaps.

The Impact of Sweep Angle on Stepped Planing Hull Performance

2021 ◽  
Author(s):  
Nicholas Husser ◽  
Stefano Brizzolara
Keyword(s):  
Dynamic Stability ◽  
Sweep Angle ◽  
High Speeds ◽  
Free Running ◽  
Low Speeds ◽  
And Performance ◽  
The Impact

In this study the impact of sweep angle on stepped hull resistance, running attitude, and dynamic stability is investigated for a range of planing speeds from ventilation inception (𝐹𝛻≈2) to high planing speeds (𝐹𝛻≈7) using RANS CFD. Potential performance benefits of the step are isolated for three speeds and two displacements using fixed trim simulations. Differences in running attitude and dynamic stability are investigated using free running simulations at the highest speed for a range of LCG locations. Finally, any differences in ventilation inception and performance at low speeds are investigated using fixed trim and heave simulations. The study shows that swept forward steps do not necessarily ventilate earlier than other step designs but do provide resistance reductions at 𝐹𝛻<5 compared to swept aft and unstepped designs. However, at 𝐹𝛻>5, swept forward steps demonstrate significant resistance increases compared to unswept and swept aft steps. At high speeds, swept aft steps provide improved dynamic stability compared to other step designs without a resistance penalty when compared to unswept steps.

Friction and Tribological Considerations for Nanometer Range Machining

2001 ◽  
Author(s):  
Som Chattopadhyay
Keyword(s):  
Mathematical Model ◽  
High Precision ◽  
Local Deformation ◽  
Experimental Results ◽  
Precision Machining ◽  
Complex Motion ◽  
Positioning Accuracy ◽  
Nanometer Range ◽  
Motion Characteristic ◽  
Low Speeds

Abstract Positioning accuracy within the range of nanometers is required for high precision machining applications. The implementation of such a range is difficult through the slides because of (a) irregular nature of friction at the slider-guideway interface, and (b) complex motion characteristic at very low speeds. The complexity arises due to the local deformation at the interface prior to breakaway, which is known as microdynamics. In this work prior experimental results exhibiting microdynamics have been appraised, and mathematical model developed to understand this behavior.

Part II: Steady aerofoil-spoiler characteristics

1987 ◽  
Vol 91 (908) ◽  
pp. 359-366
Keyword(s):  
Separated Flow ◽  
Experimental Results ◽  
Surface Singularity ◽  
Separation Region ◽  
Two Dimensional ◽  
Trailing Edge ◽  
Singularity Method ◽  
Total Head ◽  
Low Speeds ◽  
Theoretical Results

Summary A surface singularity method has been formulated to predict two-dimensional spoiler characteristics at low speeds. Vorticity singularities are placed on the aerofoil surface, on the spoiler surface, on the upper separation streamline from the spoiler tip and on the lower separation streamline from the aerofoil trailing edge. The separation region is closed downstream by two discrete vortices. The flow inside the separation region is assumed to have uniform total head. The downstream extent of the separated wake is an empirical input. The flows both external and internal to the separated regions are solved. Theoretical results have been obtained for a range of spoiler-aerofoil configurations which compare reasonably with experimental results. The model is deficient in that it predicts a higher compression ahead of the spoiler than obtained in practice. Furthermore, there is a minimum spoiler angle below which a solution is not possible; it is thought that this feature is related to the physical observation that at small spoiler angles, the separated flow from the spoiler reattaches on the aerofoil upper surface ahead of the trailing edge.

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