Hertzian Damping, Tooth Friction and Bending Elasticity in Gear Impact Dynamics

1987 ◽  
Vol 109 (2) ◽  
pp. 189-196 ◽  
Author(s):  
D. C. H. Yang ◽  
J. Y. Lin
Keyword(s):  
Coulomb Friction ◽  
High Speed ◽  
Impact Dynamics ◽  
Relative Importance ◽  
Impact Model ◽  
Bending Energy ◽  
Modified Model ◽  
Bending Elasticity ◽  
Gear Geometry ◽  
Simulation Package

This investigation presents an analytical and computer-aided study on the dynamics of meshing gears with backlash. Based on the rotary gear impact model of Yang and Sun, a modified model with additional considerations of bending deflection, axial compression, and Coulomb friction is developed. Despite the complexity in gear geometry, formulas for modeling these phenomena are all analytically derived. A computer simulation package is developed for this model. Consequently gear impact dynamics and the relative importance among the included considerations are studied. Results show that the energy loss due to the Hertzian damping is usually larger than that from the Coulomb friction, and the axial compressive energy is negligible in comparison to tooth bending energy. It is believed that the model and the finding in this study contribute toward understanding of impact behaviors of high-speed geared systems with frequent stop-and-start or intermittent motions.

Studies of Stick-Slip Friction, Presliding Displacement, and Hunting

2000 ◽  
Vol 124 (1) ◽  
pp. 111-117 ◽  
Author(s):  
Ruh-Hua Wu ◽  
Pi-Cheng Tung
Keyword(s):  
Coulomb Friction ◽  
High Speed ◽  
Experimental Studies ◽  
Friction Model ◽  
Smooth Transition ◽  
Stick Slip ◽  
Modified Model ◽  
Cyclic Motion ◽  
Coulomb Friction Model ◽  
The Stability

This paper presents the studies of stick-slip friction, presliding displacement and its influence on hunting. Experimental studies reveal that presliding displacement could affect the stability of hunting. A modified Coulomb friction model integrating presliding displacement in the microsliding regime is proposed to demonstrate such effect. Finally, step responses obtained from experiments and from the modified model are compared. These comparisons yield the conclusion that the transition of friction between the sticking state and the sliding state is smooth and continuous, not abrupt. Such a smooth transition of friction is critical to the studies of systems performing high-speed cyclic motion.

Acoustical behavior of loss-optimized involute gears

2021 ◽  
Vol 263 (5) ◽  
pp. 1574-1585
Author(s):  
Sebastian Sepp ◽  
Joshua Goetz ◽  
Karsten Stahl
Keyword(s):  
High Speed ◽  
Low Noise ◽  
Test Results ◽  
Motor Speed ◽  
Power Train ◽  
Higher Power ◽  
Involute Gears ◽  
Gear Geometry ◽  
Drive Systems ◽  
Design Calculations

The progressing electrification of vehicle drive systems focuses more and more on efficient high-speed concepts. Increasing the motor speed leads to a higher power density of the electrified power train and thereby to an increased range for battery electric vehicles. The high rotational speeds cause new challenges in designing gearboxes regarding the efficiency and the acoustical behavior. Most present gearings in conventional vehicles are designed with high tooth depths to ensure low noise excitation behavior combined with the best possible efficiency. By changing the gear geometry to smaller tooth depths with higher pressure angles, it is possible to further decrease gear losses. However, the loss-optimized gear geometry must not jeopardize the beneficial acoustical behavior. In theoretical studies, the acoustical behavior of loss-optimized gears are investigated and compared to gearings designed according to the state of the art. Design calculations of the excitations of all ideal gears without deviations are on similar levels. However, application of such gear geometries faces severe challenges because the sensitivity to manufacturing deviations may be high. In this paper, simulation results and test results between low-NVH gears and loss-optimized gears are documented and analyzed.

Estimation of Dynamic Forces in Very High-Speed Impact Forging

1966 ◽  
Vol 88 (4) ◽  
pp. 369-372 ◽  
Author(s):  
M. J. Hillier
Keyword(s):  
Approximate Solution ◽  
Velocity Field ◽  
Plane Strain ◽  
Energy Method ◽  
Coulomb Friction ◽  
High Speed ◽  
Admissible Velocity ◽  
High Speed Impact ◽  
Dynamic Forces ◽  
Very High

A study is made of three methods of estimating die loads in impact forging: By approximate solution of the equations of equilibrium; by an energy method, assuming plane sections remain plane; and using the energy method in association with a kinematically admissible velocity field. Results are given for die pressures and die loads for axisymmetric and plane-strain forging of disks and slabs with smooth dies, perfectly rough dies, and for the case of Coulomb friction.

Study on Prediction Model of Shrinkage and Creep of Prestressed Concrete Beam in Passenger Dedicated Line

2011 ◽  
Vol 255-260 ◽  
pp. 3998-4002
Author(s):  
Jun Li Luo ◽  
Zhi Sheng Xu ◽  
Jun Li ◽  
Ji Hao Yang
Keyword(s):  
Prestressed Concrete ◽  
High Speed ◽  
Concrete Beam ◽  
Influence Factors ◽  
Creep Model ◽  
High Speed Railway ◽  
Modified Model ◽  
Shrinkage And Creep ◽  
Prestressed Concrete Bridge ◽  
Passenger Dedicated Line

To improve the calculation precision of deformation in prestressed concrete bridge in passenger dedicated line and accurately predict the development of shrinkage and creep in bridge, a universal applicable modified model was put forward in this paper based on ACI 209R(1992) shrinkage and creep model. In the modified model, three influence factors-slump, strength and reinforcement - are corrected. And the modified model results were compared with the experimental results. It shows that the modified model can more accurately predict the development of shrinkage and creep of high-speed railway bridge and better accord with the law of it.

Third Paper: Wind Gusts Measured on High-Speed Roads

1973 ◽  
Vol 187 (1) ◽  
pp. 354-360 ◽  
Author(s):  
N. P. Smith
Keyword(s):  
High Speed ◽  
Relative Importance ◽  
The Road ◽  
Wind Gusts ◽  
Wind Patterns

Cross-winds increase in importance as more motorways are built; measurements made with an instrumented car in windy conditions on motorways are described. It is demonstrated that wind patterns and the occurrence of most gusts are dependent on the topography and features, such as bridges and cuttings, adjacent to the road. The relative importance of the various gust-causing features is enumerated and typical gusts, measured near these features, are shown. The value of artificial cross-winds is discussed, with particular reference to the realism of the M.I.R.A. facility.

Application of Robust Control Law for Linear Slider

2008 ◽  
Vol 2 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Satoshi Yamamoto ◽  
◽  
Shinji Wakui
Keyword(s):  
Robust Control ◽  
Disturbance Observer ◽  
High Speed ◽  
Control Law ◽  
Model Matching ◽  
Positioning Accuracy ◽  
Control Laws ◽  
Modified Model ◽  
Applied Model ◽  
Model Following

The most important specifications in precision positioning are positioning accuracy and settling time. When a positioning sensor based on required specifications is installed in equipment, every effort is made to realize throughput, i.e., high-speed positioning. We applied model-matching 2-degree-of-freedom (DOF) control to a linear slider to realize positioning, but found that positioning waveforms were uneven under different conditions. To overcome this problem, we applied robust control laws, e.g., MM-2DOF with a disturbance observer, robust 2DOF control, and modelfollowing 2DOF control to the linear slider. A comparative study confirmed experimentally that robust 2DOF control was most suitable. To improve modelfollowing 2DOF control, we modified model-following 2DOF control and its robust positioning.

Determining the Effects of Coulomb Friction on the Dynamics of Bearings and Transmissions in Robot Mechanisms

1993 ◽  
Vol 115 (2) ◽  
pp. 231-240 ◽  
Author(s):  
A. Gogoussis ◽  
M. Donath
Keyword(s):  
Coulomb Friction ◽  
High Speed ◽  
Robot Motion ◽  
Robot Dynamics ◽  
Quantitative Characterization ◽  
Joint Coordinates ◽  
Dynamics Problems ◽  
And Control

In order to accurately model robots for precision applications where dynamics are significant, it is important to include the effects of Coulomb friction in the bearings and transmissions. The general guidelines for analyzing friction at the joints will be discussed. It will be shown that friction can be related to the joint coordinates and their first and second time derivatives. The resulting extended robot dynamics formulation will be investigated as it applies to the inverse and forward robot dynamics problems. The analytical dependency of Coulomb friction on joint interactions is explicitly examined. As an illustration of friction effects in transmissions, we elaborate on the friction in harmonic drives and develop a method for its evaluation. The effect of friction in the bearings on the dynamics is also considered and a quantitative characterization of several specific cases is provided. This study is significant to understanding the design and control issues as they relate to achieving high speed precision robot motion.

scholarly journals Using geometric algebra to represent curvature in shell theory with applications to Starling resistors

2017 ◽  
Vol 4 (11) ◽  
pp. 171212
Author(s):  
A. L. Gregory ◽  
A. Agarwal ◽  
J. Lasenby
Keyword(s):  
Curvature Tensor ◽  
Geometric Algebra ◽  
Shell Theory ◽  
Constitutive Law ◽  
Working Fluid ◽  
Scaling Analysis ◽  
Relative Importance ◽  
Bending Energy ◽  
Initial Curvature ◽  
Flexible Tubes

We present a novel application of rotors in geometric algebra to represent the change of curvature tensor that is used in shell theory as part of the constitutive law. We introduce a new decomposition of the change of curvature tensor, which has explicit terms for changes of curvature due to initial curvature combined with strain, and changes in rotation over the surface. We use this decomposition to perform a scaling analysis of the relative importance of bending and stretching in flexible tubes undergoing self-excited oscillations. These oscillations have relevance to the lung, in which it is believed that they are responsible for wheezing. The new analysis is necessitated by the fact that the working fluid is air, compared to water in most previous work. We use stereographic imaging to empirically measure the relative importance of bending and stretching energy in observed self-excited oscillations. This enables us to validate our scaling analysis. We show that bending energy is dominated by stretching energy, and the scaling analysis makes clear that this will remain true for tubes in the airways of the lung.

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