Interface Properties Due to Microslip From Vibration Measurement

1999 ◽  
Vol 123 (1) ◽  
pp. 230-233 ◽  
Author(s):  
H. A. Sherif ◽  
T. M. Abu Omar
Keyword(s):  
Contact Stiffness ◽  
Single Point ◽  
Peak Frequency ◽  
Vibration Measurement ◽  
Interface Properties ◽  
Flat Surfaces ◽  
Dry Contact ◽  
Impulse Excitation ◽  
Interface Parameters ◽  
Two Degree Of Freedom

A method of measuring contact stiffness and friction damping at interacting plane surfaces of a mechanical system comprised of two sub-structures in dry contact is presented. The method is based on the measurement of displacement ratio of the contacting sub-structures as a function of frequency due to light impulse excitation at a single point on any of the two sub-structures. The theoretical analysis depends on a very simple model of a two-degree-of-freedom system with elastic coupling. The effects of applied normal loads, and contact configuration on the interface parameters are shown. The theoretical and experimental analyses show that the interface properties for the flat-on-flat surfaces of the two contacting sub-structures can be determined from the measured peak amplitude and peak frequency of the microslip in the frequency domain.

scholarly journals Contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions

Friction ◽  
2021 ◽  
Author(s):  
Zongzheng Wang ◽  
Wei Pu ◽  
Xin Pei ◽  
Wei Cao
Keyword(s):  
Contact Stiffness ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Spiral Bevel Gears ◽  
Bevel Gears ◽  
Dry Contact ◽  
Spiral Bevel ◽  
Stiffness And Damping ◽  
Lubrication Conditions ◽  
Film Lubrication

AbstractExisting studies primarily focus on stiffness and damping under full-film lubrication or dry contact conditions. However, most lubricated transmission components operate in the mixed lubrication region, indicating that both the asperity contact and film lubrication exist on the rubbing surfaces. Herein, a novel method is proposed to evaluate the time-varying contact stiffness and damping of spiral bevel gears under transient mixed lubrication conditions. This method is sufficiently robust for addressing any mixed lubrication state regardless of the severity of the asperity contact. Based on this method, the transient mixed contact stiffness and damping of spiral bevel gears are investigated systematically. The results show a significant difference between the transient mixed contact stiffness and damping and the results from Hertz (dry) contact. In addition, the roughness significantly changes the contact stiffness and damping, indicating the importance of film lubrication and asperity contact. The transient mixed contact stiffness and damping change significantly along the meshing path from an engaging-in to an engaging-out point, and both of them are affected by the applied torque and rotational speed. In addition, the middle contact path is recommended because of its comprehensive high stiffness and damping, which maintained the stability of spiral bevel gear transmission.

Study of Oil Starvation in Journal Bearing Using Acoustic Emission and Vibration Measurement Techniques

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Surojit Poddar ◽  
N. Tandon
Keyword(s):  
Acoustic Emission ◽  
Journal Bearing ◽  
Measurement Techniques ◽  
Peak Frequency ◽  
Vibration Measurement ◽  
Frequency Range ◽  
Frequency Shifts ◽  
Deformation And Fracture ◽  
Asperity Contacts ◽  
Ae Signals

Abstract This present article evaluates the state of starvation in a journal bearing using acoustic emission (AE) and vibration measurement techniques. A journal bearing requires a constant supply of oil in an adequate amount to develop a hydrodynamic film, thick enough to separate the surfaces and avoid asperity contacts. On a microscopic level, the surface interaction under starved lubrication results in deformation and fracture of asperities. This causes a proportionate increase in AE and vibration. The AE activities resulting from asperities interaction have significant energy in the frequency range of 100–400 kHz with peak frequencies in the range of 224–283 kHz. Further, the peak frequency shifts from the higher to lower side as the asperity interaction transits from the elastic to plastic contact. This information derived from the spectral analysis of AE signals can be used to develop condition monitoring parameters to proactively control the lubrication and prevent bearing failure.

A New Imaging Method for Arterial Tubes Based on Vibration Measurement

2003 ◽  
Author(s):  
Xiaoming Zhang ◽  
Mostafa Fatemi ◽  
James F. Greenleaf
Keyword(s):  
Focal Point ◽  
Single Point ◽  
Vibration Measurement ◽  
Ultrasound Transducer ◽  
Imaging Method ◽  
Large Artery ◽  
Large Radius ◽  
Modal Shape ◽  
Measured Velocity ◽  
Gel Phantom

A new method for imaging and detecting modal shapes of vessels is introduced. Theory is developed that predicts the measured velocity is proportional to the value of the mode shape at the focal point of the ultrasound beam. Experimental a cylindrical gel phantom of large radius. This model simulates approximately a large artery and the surrounding body. The fundamental frequency was measured 83 Hz for the tube-phantom system. At this frequency the ultrasound transducer was scanned across the vessel plane with velocity measurement at one single point on the vessel and on the phantom by laser. The images obtained show clearly the interior tube and the modal shape of the tube.

Measurement and Modeling of Normal Contact Stiffness and Contact Damping at the Meso Scale

2005 ◽  
Vol 127 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Xi Shi ◽  
Andreas A. Polycarpou
Keyword(s):  
Wear Debris ◽  
Rough Surfaces ◽  
Contact Stiffness ◽  
Damping Ratio ◽  
Minute Amount ◽  
Normal Contact ◽  
Flat Surfaces ◽  
Normal Contact Stiffness ◽  
Contact Parameters ◽  
Meso Scale

Modeling of contact interfaces that inherently include roughness such as joints, clamping devices, and robotic contacts, is very important in many engineering applications. Accurate modeling of such devices requires knowledge of contact parameters such as contact stiffness and contact damping, which are not readily available. In this paper, an experimental method based on contact resonance is developed to extract the contact parameters of realistic rough surfaces under lightly loaded conditions. Both Hertzian spherical contacts and flat rough surfaces in contact under normal loads of up to 1000 mN were studied. Due to roughness, measured contact stiffness values are significantly lower than theoretical values predicted from smooth surfaces in contact. Also, the measured values favorably compare with theoretical values based on both Hertzian and rough contact surfaces. Contact damping ratio values were found to decrease with increasing contact load for both Hertzian and flat surfaces. Furthermore, Hertzian contacts have larger damping compared to rough flat surfaces, which also agrees with the literature. The presence of minute amount of lubricant and wear debris at the interface was also investigated. It was found that both lubricant and wear debris decrease the contact stiffness significantly though only the lubricant significantly increases the damping.

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.

Theoretical and Experimental Contact Stiffness Characterisation of Nominally Flat Surfaces

2012 ◽  
Vol 186 ◽  
pp. 107-113 ◽  
Author(s):  
Iuliana Piscan ◽  
Agusmian P. Ompusunggu ◽  
Thierry Janssens ◽  
Nicolae Predincea
Keyword(s):  
Normal Load ◽  
Contact Stiffness ◽  
Contact Theory ◽  
Tangential Displacement ◽  
Tangential Contact ◽  
Flat Surfaces ◽  
Elastic Bodies ◽  
Order Of Magnitude ◽  
Theoretical Results ◽  
Good Agreement

In this study the tangential contact stiffness between two elastic bodies having nominally flat surfaces with different material combinations is investigated. The tangential contact stiffness between these two elastic bodies is first calculated based on the Greenwood-Williamson-McCool contact theory. Then, the tangential contact stiffness is determined by experimental investigation on a tribometer under the effect of different values of normal load and tangential displacement amplitude. The tangential contact stiffnesses obtained from the experimental data show a good agreement with the theoretical results, where the trends are similar and they are in the same order of magnitude.

scholarly journals Influence of mineral composition on spectral induced polarization in sediments

2017 ◽  
Vol 209 (1) ◽  
pp. 186-191 ◽  
Author(s):  
Daniil Chuprinko ◽  
Konstantin Titov
Keyword(s):  
Phase Shift ◽  
Polarization Effect ◽  
Peak Frequency ◽  
Induced Polarization ◽  
Published Data ◽  
Transport Numbers ◽  
Interface Properties ◽  
Membrane Polarization ◽  
Spectral Induced Polarization ◽  
Modelling Data

Summary We discuss a membrane polarization effect that can occur when the walls of two sequential pores are built of different minerals, with different interface properties (the zeta potential and the partition coefficient). The differences in the interface properties lead to a difference in the ion transport numbers (even if the two aforementioned pores are of the same radius) and, therefore, to a membrane polarization when an electrical field is applied. Based on published data, we discuss differences in the interface properties of common minerals: silicates, carbonates, clay minerals, organic material, etc. Based on the theory presented by Marshall and Madden and recently extended by Bücker and Hördt we semi-analytically model the membrane polarization effect for a system that consists of two pores of equal radius. We calculate maximum values of the phase shift as a function of the pore radius. We also calculate values of the peak frequency (the frequency corresponding to the phase-shift peak) as a function of the pores’ lengths. The modelling results show that the phase shift can assume values of up to 80 mrad for pores with radii of about 0.1 μm. The peak frequency values are within the typical frequency range of spectral induced polarization measurements and, therefore, the effect can be detected. Based on the modelling data, we hypothesize that the effect of differences in interface properties of the minerals constituting the walls of sequential pores can be superimposed on the polarization effect of the Stern layer coating the mineral grains and the classical membrane polarization effect.

The Dynamic Frictional Performance of Damping-Rings in Labyrinth Air Seal for Vibration Control

2009 ◽  
Author(s):  
Liang Zeng ◽  
Lin Li
Keyword(s):  
Vibration Control ◽  
Contact Stiffness ◽  
Single Point ◽  
Flexural Vibration ◽  
Forced Response ◽  
Theoretic Model ◽  
Frictional Performance ◽  
Damping Rings ◽  
Sine Signal

The application of damping-rings to rotor/stator components in aero-engine was proved effective in protecting labyrinth air seals and the cylindrical walls of annular chambers against flexural vibration and fatigue failures excited by various disturbing forces. In view of the possibility of resonance, determination of the vibration characteristics of the labyrinth air seals with damping-rings by theoretic model, experiment or both is of vital importance in the design and development procedure. This paper built up the equivalent linear model of interface between the seals and damping-rings by introducing the local contact stiffness, and then researched the forced response of labyrinth air seals with two types of damping-ring under single-point exciter with sine signal. The dynamic response experiments of the shell with different damping-rings verified the validity of the proposed simplified model and the simulation results. The influence of variable parameters, such as the width and installed position of damping-rings was also discussed. In the experiments the damping-ring showed the great effect in vibration control by friction damping and contact stiffness.

Sign in / Sign up

Export Citation Format

Share Document