Effects of Design Parameters on Bouncing Vibrations of a Single-DOF Contact Slider and Necessary Design Conditions for Perfect Contact Sliding

1999 ◽  
Vol 121 (3) ◽  
pp. 596-603 ◽  
Author(s):  
Kyosuke Ono ◽  
Kohei lida ◽  
Kan Takahashi
Keyword(s):  
Critical Frequency ◽  
Contact Stiffness ◽  
Damping Ratio ◽  
Wide Frequency Range ◽  
Design Parameters ◽  
Frequency Range ◽  
Elastic Impact ◽  
Spring System ◽  
Perfect Contact ◽  
Contact Slider

The general characteristics of the bouncing vibrations of a IDOF contact slider model over the surface of a harmonic wavy disk were studied both by computer simulation and theoretical analysis. The necessary design conditions for a contact slider and the surface of a disk were discussed in terms of perfect contact sliding and wear durability. It was found that the bouncing vibrations change with the amount of waviness amplitude A(fr) at the contact resonant frequency fr(=(1/2π)kc/m) relative to static penetration depth δ, or fr relative to limiting critical frequency fcl, above which the downward acceleration of the surface of a disk is larger than that of a slider due to slider load. When the contact stiffness is large enough so that δ < A(fr) (fcl < fr), the slider bounces with a large amplitude similar to an elastic impact in a wide frequency range. When the contact stiffness is small enough so that δ > A(fr) (fcl > fr), bouncing vibrations occur near the contact resonance, similar to the resonance of a nonlinear soft spring system. Here, the bouncing vibration can be completely eliminatedby increasing the contact damping ratio and decreasing the slider mass and the waviness amplitude.

Analysis of Bouncing Vibrations of a 2-DOF Tripad Contact Slider Model With Air Bearing Pads Over a Harmonic Wavy Disk Surface

1999 ◽  
Vol 121 (4) ◽  
pp. 939-947 ◽  
Author(s):  
Kyosuke Ono ◽  
Kan Takahashi
Keyword(s):  
Contact Stiffness ◽  
Disk Surface ◽  
Design Parameters ◽  
Air Bearing ◽  
Static Contact ◽  
Tracking Ability ◽  
The Coefficient Of Friction ◽  
Bearing Stiffness ◽  
Perfect Contact ◽  
Contact Slider

In this study, the authors numerically analyzed the bouncing vibrations of a two-degree-of-freedom (2-DOF) model of a tripad contact slider with air bearing pads over a harmonic wavy disk surface. The general features of bouncing vibrations were elucidated in regard to the modal characteristics of a 2-DOF vibration system and design parameters such as contact stiffness, contact damping, air hearing stiffness, the rear to front air bearing stiffness ratio, static contact force and the coefficient of friction. The design of a contact slider was discussed in terms of tracking ability and wear durability. In addition, two sample designs of a perfect contact slider with sufficient wear durability were also presented.

Analysis of Bouncing Vibrations of a 2-DOF Model of Tripad Contact Slider Over a Random Wavy Disk Surface

2000 ◽  
Vol 123 (1) ◽  
pp. 159-167 ◽  
Author(s):  
Kohei Iida ◽  
Kyosuke Ono
Keyword(s):  
Contact Stiffness ◽  
Damping Ratio ◽  
Disk Surface ◽  
Design Parameters ◽  
Air Bearing ◽  
Continuous Contact ◽  
Design Concepts ◽  
The Coefficient Of Friction ◽  
Bearing Stiffness ◽  
Contact Slider

We numerically analyzed the bouncing vibrations of a two-degree-of-freedom (2-DOF) model of a tri-pad contact slider with air bearing pads over a random wavy surface and manifested the design conditions of a contact slider. The effects of the design parameters such as air bearing stiffness, contact damping ratio, the coefficient of friction, and the characteristics of the disk surface waviness on dynamic behavior and the contact sliding ability of the slider have been investigated. As a result, we found that friction force decreases the contact sliding ability at the boundary of the intermittent and continuous contact sliding. We also found that the distance between the rear air bearing center and the contact pad has a significant effect on the contact sliding ability. If the contact pad is apart from the rear air bearing center, the contact pad tends to separate from the disk. Based on this analytical study, we have proposed two design concepts: (1) Make the distance between the rear air bearing center and the contact pad as small as possible; in this case, the larger the rear air bearing stiffness results are, the better the contact ability is; (2) If some distance between the rear air bearing center and the contact pad is inevitable, then make the rear air bearing stiffness much smaller than the contact stiffness.

Computer Analysis of Bouncing Vibration and Tracking Characteristics of a Point Contact Slider Model Over Random Disk Surfaces

1999 ◽  
Vol 121 (3) ◽  
pp. 587-595 ◽  
Author(s):  
Kyosuke Ono ◽  
Kan Takahashi ◽  
Kohei Iida
Keyword(s):  
Contact Stiffness ◽  
Point Contact ◽  
Disk Surface ◽  
Design Parameters ◽  
Random Surface ◽  
Disk Interface ◽  
Tracking Ability ◽  
Interface Parameters ◽  
Parameter Values ◽  
Contact Slider

This study is a computational analysis of the bouncing vibration of a point contact slider model over computer generated random disk surfaces and the design conditions of slider to disk interface parameters necessary for contact recording. The Gaussian random surface of a disk with various standard deviations and frequency characteristics is generated by using a modified midpoint displacement algorithm. From the calculated results of bouncing vibration of a slider for various parameter values, it was found that the decrease in contact stiffness and increase in slider load can significantly reduce the bouncing vibration as well as the increase in contact damping and the smoothness of the surface. It was also found that the bouncing vibration spectrum of a contact slider over a simulated disk surface agreed closely with the experimental results presented in a previous study by the authors. The maximum and rms values of the spacing and the contact force were examined for various design parameters. The design conditions of the contact pad to the disk interface were discussed in terms of tracking ability and wear durability for slider loads of 0.5 mN and 5 mN.

Damping Control in a Sandwich Structure With SMP Core

2015 ◽  
Author(s):  
Pauline Butaud ◽  
Morvan Ouisse ◽  
Emmanuel Foltête
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Sandwich Structure ◽  
Damping Ratio ◽  
Shape Memory Polymer ◽  
Viscoelastic Model ◽  
Element Model ◽  
Numerical Approach ◽  
Wide Frequency Range ◽  
Frequency Range

A shape memory polymer (SMP), the tBA/PEGDMA, is elaborated and characterized. The dynamic mechanical characterization of this SMP highlights promising damping properties. The frequency and temperature dependency of the SMP is represented by a viscoelastic model allowing the introduction of the material in the design process of complex structures. A composite sandwich is developed by coupling the SMP with aluminum skins. A finite element model is developed for modeling the behavior of the SMP when integrated in a sandwich structure. The damping performances obtained by the numerical approach are validated experimentally using modal analysis. The experimental results are found to be in good agreement with the predictions of the finite element model. Furthermore, it is found that the controlled heating of the SMP core allows damping the structure over a wide frequency range. The SMP core temperature is tuned from the time-temperature superposition through a calibration curve to correspond to optimal values of damping ratio in the frequency range of interest; a vibration attenuation of about 20dB is observed.

Computer Analysis of the Dynamic Contact Behavior and Tracking Characteristics of a Single-Degree-of-Freedom Slider Model for a Contact Recording Head

1995 ◽  
Vol 117 (1) ◽  
pp. 124-129 ◽  
Author(s):  
Kyosuke Ono ◽  
Hiroshi Yamamura ◽  
Takaaki Mizokoshi
Keyword(s):  
Contact Stiffness ◽  
Time History ◽  
Dynamic Contact ◽  
Disk Surface ◽  
Degree Of Freedom ◽  
Design Parameters ◽  
Single Degree Of Freedom ◽  
Contact Behavior ◽  
Single Degree ◽  
Contact Slider

This paper presents a new theoretical approach to the dynamic contact behavior and tracking characteristics of a contact slider that is one of the candidates of head design for future high density magnetic recording disk storages. A slider and its suspension are modeled as a single-degree-of-freedom vibration system. The disk surface is assumed to have a harmonic wavy roughness with linear contact stiffness and damping. From the computer simulation of the time history of the slider motion after dropping from the initial height of 10 nm, it is found that the contact vibration of the slider can attenuate and finally track on the wavy disk surface in a low waviness frequency range. As the waviness frequency increases, however, the slider cannot stay on the disk surface and comes to exhibit a variety of contact vibrations, such as sub- and super-harmonic resonance responses and finally comes to exhibit non-periodic vibration. It is also found that, among design parameters, the slider load to mass ratio and contact damping can greatly increase the surface waviness frequency and amplitude for which the stable tracking of a contact slider is possible.

scholarly journals The Case Study of Pseudoexcitation Method Combining Self-Adaptive Gauss Integration in Random Vibration Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Ning Chen ◽  
Siyu Zhu ◽  
Yongle Li
Keyword(s):  
Vibration Analysis ◽  
Random Vibration ◽  
Critical Frequency ◽  
Damping Ratio ◽  
Structural Response ◽  
Coupled System ◽  
Random Excitation ◽  
Wide Frequency Range ◽  
Random Vibration Analysis ◽  
Self Adaptive

The pseudoexcitation method (PEM) can improve efficiency of random vibration analysis. However, for large-sized structures with wide frequency range of response, the workload of calculation is heavy if conventional integration methods, such as trapezoidal integration, are used to combine with the PEM to calculate structural response. In such case, self-adaptive technology is induced to combine with the PEM to form an efficient method for solving random vibration. During calculation, this method can realize the adaptability of random excitation to actual structural response, identify automatically critical frequency intervals of random excitation, and process intelligently the identified critical frequency intervals and noncritical frequency intervals. Based on the identified frequency intervals, Gauss integration is carried out to obtain response results with random characteristics. The computational efficiency and accuracy of PEM-SGI are verified by wind-induced performance of the slender bridge tower. Finally, the influence of damping ratio of the bridge structure and train marshalling on vehicle-bridge coupled system is investigated to further verify the application of the proposed method. Results show that the efficiency of solving random vibration can be improved by the present method.

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