Coulomb Friction and Optimal Rocker Arm Ratio for High-Speed Cam Systems

1986 ◽  
Vol 108 (3) ◽  
pp. 340-344 ◽  
Author(s):  
A. P. Pisano ◽  
Hong Tao Chen
Keyword(s):  
Coulomb Friction ◽  
High Speed ◽  
Dynamic Parameter ◽  
Kinematic Parameter ◽  
Operating Speed ◽  
Dynamic Parameters ◽  
Lumped Model ◽  
Design Charts ◽  
Local Extrema ◽  
Cam Systems

The operating speed of a high-speed cam system can be maximized by the proper choice of both kinematic and dynamic parameters of a lumped model. Considering rocker arm ratio as an unconstrained kinematic parameter and Coulomb friction as an unconstrained dynamic parameter, it was found that the camshaft speed at which toss occurred was characterized by several local extrema, all of which were sensitive to the presence of Coulomb friction. For a particular cam system and two separate cam lift curves, design charts have been developed to aid in the choice of optimal rocker arm ratio for maximum operating speed in the presence of Coulomb friction.

Coulomb Friction in High-Speed Cam Systems

1984 ◽  
Vol 106 (4) ◽  
pp. 470-474 ◽  
Author(s):  
A. P. Pisano
Keyword(s):  
Coulomb Friction ◽  
High Speed ◽  
Valve Train ◽  
Dynamic Data ◽  
Coulomb Damping ◽  
Dynamic Coefficients ◽  
Lumped Parameter ◽  
Cam Systems ◽  
Speed Response

Coulomb friction in the rocker arm pivot of a high-speed cam system was quantified and its effect on high-speed response was examined. Experimental dynamic data from an automotive valve train was used to determine the static and dynamic coefficients. A lumped-parameter dynamic model was used to determine the role of Coulomb damping in actuation forces and valve toss.

scholarly journals Research into Correlation between the Lubrication Mode of Contact Surfaces and Dynamic Parameters of Turbo-Generator Transmissions

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Marek Kočiško ◽  
Petr Baron ◽  
Monika Telíšková ◽  
Jozef Török ◽  
Anna Bašistová
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
High Speed ◽  
Oil Quality ◽  
The State ◽  
Dynamic Parameters ◽  
High Frequency Vibration ◽  
Turbo Generator ◽  
Friction Mode ◽  
Contact Surfaces

The paper presents the results of an experimental study aimed at assessing the correlation between the measurement of dynamic parameters (vibration, high-frequency vibration, and acoustic emission) and the analysis of friction mode and the state of lubrication of the contact surfaces of two gearboxes in the turbo-generator assembly (high-speed single-body steam turbine—gearbox—generator) with the transmission power of no more than 50 MW. The analysis confirmed the assumption of a significant correlation of the monitored high-frequency vibration signal with the unsatisfactory engagement of the gear teeth. Through vibration analysis, an increased level of the tooth vibration component and vibration multiples with increased acoustic emission were identified in gearbox operation. The gear oil of one of the gearboxes examined showed a loss of additive elements in the real operation of the contact surfaces of the teeth engagement. The trend analysis confirmed the complexity of the monitored transmission operation in terms of the friction mode and the influence of the oil quality on the state of the tooth flank microgeometry.

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.

Dynamic Response of the Vertical Rotor System to Base Excitation

2008 ◽  
Author(s):  
Jianli Zuo ◽  
Jianjun Wu ◽  
Ping Li ◽  
Shenjian Su
Keyword(s):  
Dynamic Response ◽  
Physical Model ◽  
High Speed ◽  
Lagrange Equation ◽  
Rotor System ◽  
Operating Speed ◽  
Base Excitation ◽  
Rotating Machine ◽  
Vertical Rotor ◽  
Rotary Speed

The physical model of a high-speed vertical rotating machine was taken as the example. The motion differential equations of the rotor system were established by the Lagrange equation and numerically solved by the Wilson-θ method. The whirling characteristics of the rotor excited by the base’s harmonic motions have been analyzed. The whirling directions are different between the rotor’s upper and lower ends. And the whirling characteristics of the rotor vary with the frequency of the base’s motion. Besides, there exists such a region of the rotor’s rotary speed, in which the whirling characteristics and amplitudes of the rotor system are relatively steady, so the aseismic tests at a certain lower speed can be done to examine the aseismic capability of the rotor system at operating speed.

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.

Underwater Vehicle System Identification Using Laser Light, Decoupled Dynamics and Evolutionary Algorithm

2015 ◽  
Author(s):  
Yu-Cheng Chou
Keyword(s):  
System Identification ◽  
Dynamic Models ◽  
Laser Light ◽  
Autonomous Underwater Vehicles ◽  
Dynamic Parameter ◽  
Underwater Vehicles ◽  
Evolutionary Optimization ◽  
Dynamic Parameters ◽  
Optimization Strategy ◽  
Scanned Images

This paper presents a new hybrid method, which integrates the structured laser light, decoupled dynamic models, and evolutionary optimization strategy, to identify dynamic parameters of autonomous underwater vehicles. This is the first research that investigates the utilization of laser scanned images for the system identification of underwater vehicles. The AUV’s equations of motions and the dynamic parameter identification using the AUV’s decoupled motions will be illustrated. The working principles to calculate the AUV’s positons using the structured laser light will be explained with respect to the surge and pitch motions. The evolutionary optimization strategy used to generate the AUV’s dynamic parameters will be presented.

Design and Implementation of High-Speed Dual-Modulus

2011 ◽  
Vol 109 ◽  
pp. 271-275
Author(s):  
Jian Jun Song ◽  
Liu Sun ◽  
He Ming Zhang ◽  
Hui Yong Hu
Keyword(s):  
Power Supply ◽  
Dynamic Load ◽  
High Speed ◽  
Operating Speed ◽  
Switching Circuit ◽  
Switching Sequence ◽  
Phase Switching ◽  
Measurement Result ◽  
Design And Implementation ◽  
Supply Current

This paper presents a new enhanced phase switching 15/16 dual-modulus prescaler. One more divide-by-2 stage was employed in the design compare to the conventional phase switching architecture. Since the operating speed of phase switching circuit is obviously reduced. The inverse phase switching sequence was employed in this circuit to implement glitch-free phase switching. Further more, a dynamic load master-slave DFF was employed as the first divide-by-2 stage which can increase the operating frequency of prescaler. Measurement result shows, this dual-modulus prescaler can operate at 3GHz-200MHz with 2.8mA supply current at 1.8V power supply.

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.

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