scholarly journals Measurement of moment coupling in fretting fatigue experiments

2021 ◽  
pp. 095440622110431
Author(s):  
JPJ Truelove ◽  
DA Hills ◽  
L Blades
Keyword(s):  
Contact Pressure ◽  
Shear Force ◽  
Fretting Fatigue ◽  
Load Cycle ◽  
Image Correlation ◽  
Contact Pressure Distribution ◽  
Normal Contact ◽  
Loading Cycle ◽  
Normal Contact Force ◽  
Edge Contact

Moment coupling in fretting fatigue experiments refers to the generation of moments when a shear force is applied, caused by the difficulty in designing fretting fatigue experiments where the shear is reacted out on the same plane as the contact. Digital Image Correlation is used to measure the effect of moment coupling, and a model is created to calculate the effect of the applied moment at any point during a loading cycle on near-edge contact properties. The effects of the changing contact pressure on the slip zone sizes are considered. Finally, the model derived is used to find a load cycle including the effect of normal contact force that creates a truly constant near-edge contact pressure distribution at one edge of the flat and rounded pad. Although the calibrations found in this paper are valid only for the specific rig and specimen geometry used in this paper, the method could be readily applied to other experiments.

Experimental Validation of Fretting Fatigue Strength and Fretting Wear Rate at Contact Surface of Turbine-Blade-Shroud Cover

2012 ◽  
Author(s):  
Kunio Asai ◽  
Takeshi Kudo ◽  
Hideo Yoda
Keyword(s):  
Fatigue Strength ◽  
Wear Rate ◽  
Contact Pressure ◽  
Contact Force ◽  
Contact Surface ◽  
Fretting Fatigue ◽  
Fretting Wear ◽  
Dissipated Energy ◽  
Normal Contact ◽  
Vibratory Load

In continuously coupled blade structures, fretting fatigue and wear have to be considered as supposed failure modes at the contact surface of the shroud cover, which is subject to steady contact pressure from centrifugal force and the vibratory load of the blade. We did unique fretting tests that modeled the structure of the shroud cover, where the vibratory load is only carried by the contact friction force, i.e., a type of friction. What was investigated in this study are fretting fatigue strength, wear rate, and friction characteristics, such as friction coefficient and slip-range of 12%-Cr steel blade material. The friction-type tests showed that fretting fatigue strength decreases with the contact pressure and a critical normal contact force exists under which fretting fatigue failure does not occur at any vibratory load. This differs from knowledge obtained through pad-type load carry tests that fretting fatigue strength decreases with the increase of contact pressure and that it almost saturates under a certain contact pressure. Our detailed observation in the friction-type tests clarified that this mechanism was the low contact pressure narrowing the contact area and a resulting high stress concentration at a local area. The fretting wear rate was explained by the dissipated energy rate per cycle obtained from the measured hysteresis loop between the relative slip range and the tangential contact force. This fretting wear rate per cycle is almost the same as the general adhesion wear rate when energy dissipation per cycle is high, and the former is smaller than the latter as the dissipated energy decreases. Finally, to prevent fretting fatigue and wear, we propose an evaluation design chart of the contact surface of the shroud cover based on our friction-type fretting tests.

EFFECT OF CONTACT PRESSURE ON FRETTING FATIGUE BEHAVIOR UNDER CYCLIC CONTACT LOADING

2017 ◽  
Vol 24 (Supp02) ◽  
pp. 1850032
Author(s):  
F. ABBASI ◽  
G. H. MAJZOOBI
Keyword(s):  
Fatigue Life ◽  
Contact Pressure ◽  
High Cycle Fatigue ◽  
Fe Simulation ◽  
Fatigue Behavior ◽  
Fretting Fatigue ◽  
Contact Load ◽  
Normal Contact ◽  
Contact Loading ◽  
Crack Initiation Life

In this study, the effect of contact pressure on fretting fatigue behavior of Al7075-T6 under cyclic normal contact loading is investigated. It is found that fretting fatigue life for the case of cyclic contact load was significantly less than that for constant contact load at the same axial and contact load levels, particularly for High Cycle Fatigue (HCF) conditions. The results showed that the fretting fatigue life decreased monotonically with the increase in normal contact load for all axial stresses. Examination of the fretting scars was performed using optical microscopy and numerical simulation was carried out using commercial finite element (FE) codes ABAQUS[Formula: see text] and FRANC2D/L[Formula: see text] to calculate the crack propagation life. The crack initiation life was calculated by a combination of numerical and experimental results. Finally, the FE simulation was validated by a comparison between the numerical crack growth rate and the experimental measurement using replica.

Experimental Validation of Fretting Fatigue Strength and Fretting Wear Rate at Contact Surface of Turbine-Blade-Shroud Cover

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Kunio Asai ◽  
Takeshi Kudo ◽  
Hideo Yoda
Keyword(s):  
Fatigue Strength ◽  
Wear Rate ◽  
Contact Pressure ◽  
Contact Force ◽  
Contact Surface ◽  
Fretting Fatigue ◽  
Fretting Wear ◽  
Dissipated Energy ◽  
Normal Contact ◽  
Vibratory Load

In continuously coupled blade structures, fretting fatigue and wear have to be considered as supposed failure modes at the contact surface of the shroud cover, which is subject to steady contact pressure from centrifugal force and the vibratory load of the blade. We did unique fretting tests that modeled the structure of the shroud cover, where the vibratory load is only carried by the contact friction force, i.e., a type of friction. What was investigated in this study are fretting fatigue strength, wear rate, and friction characteristics, such as friction coefficient and slip-range of 12%-Cr steel blade material. The friction-type tests showed that fretting fatigue strength decreases with the contact pressure and a critical normal contact force exists under which fretting fatigue failure does not occur at any vibratory load. This differs from knowledge obtained through pad-type load carry tests that fretting fatigue strength decreases with the increase of contact pressure and that it almost saturates under a certain contact pressure. Our detailed observation in the friction-type tests clarified that this mechanism was the low contact pressure narrowing the contact area and a resulting high stress concentration at a local area. The fretting wear rate was explained by the dissipated energy rate per cycle obtained from the measured hysteresis loop between the relative slip range and the tangential contact force. It was found that the fretting wear rate is smaller than the wear rate obtained by one-way sliding tests, and the former is much smaller than the latter as the dissipated energy decreases. Finally, to prevent fretting fatigue and wear, we propose an evaluation design chart of the contact surface of the shroud cover based on our friction-type fretting tests.

scholarly journals Numerical study of the effect of roller profile and ring skew on roller raceways contact pressure in cylindrical roller bearing

2019 ◽  
Author(s):  
J.M. Klebanov ◽  
V.R. Petrov ◽  
I.E. Adeyanov
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Numerical Study ◽  
Roller Bearing ◽  
Contact Pressure Distribution ◽  
Normal Contact ◽  
Modified Method ◽  
Normal Contact Pressure ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

Occurring during operation inhomogeneity of the contact pressure distribution between the rollers and the bearing rings due to skew affects the durability and dynamics of the bearing parts. The article describes a modified method of normal contact pressure determination according to the theory, based on the Bousinessque equation. The efficiency of the method is estimated and results of numerical simulation of normal contact pressure distribution in the contact of the roller with the raceway of the inner ring of the cylindrical roller bearing for different roller profiles, loads, and skew angles are presented. It is shown that the logarithmic profile creates the lowest pressure concentration at the ends of the roller.

Rim Slip and Bead Fitment of Tires: Analysis and Design2

2006 ◽  
Vol 34 (1) ◽  
pp. 38-63 ◽  
Author(s):  
C. Lee
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Frictional Torque ◽  
Finite Element Analyses ◽  
Inflation Pressure ◽  
Contact Pressure Distribution ◽  
Design Modification ◽  
Iterative Design ◽  
Slip Resistance ◽  
Braking Torque

Abstract A tire slips circumferentially on the rim when subjected to a driving or braking torque greater than the maximum tire-rim frictional torque. The balance of the tire-rim assembly achieved with weight attachment at certain circumferential locations in tire mounting is then lost, and vibration or adverse effects on handling may result when the tire is rolled. Bead fitment refers to the fit between a tire and its rim, and in particular, to whether a gap exists between the two. Rim slip resistance, or the maximum tire-rim frictional torque, is the integral of the product of contact pressure, friction coefficient, and the distance to the wheel center over the entire tire-rim interface. Analytical solutions and finite element analyses were used to study the dependence of the contact pressure distribution on tire design and operating attributes such as mold ring profile, bead bundle construction and diameter, and inflation pressure, etc. The tire-rim contact pressure distribution consists of two parts. The pressure on the ledge and the flange, respectively, comes primarily from tire-rim interference and inflation. Relative contributions of the two to the total rim slip resistance vary with tire types, depending on the magnitudes of ledge interference and inflation pressure. Based on the analyses, general guidelines are established for bead design modification to improve rim slip resistance and mountability, and to reduce the sensitivity to manufacturing variability. An iterative design and analysis procedure is also developed to improve bead fitment.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

One-Dimensional Contact Pressure Distribution of Radial Tires in Motion

1995 ◽  
Vol 23 (2) ◽  
pp. 116-135 ◽  
Author(s):  
H. Shiobara ◽  
T. Akasaka ◽  
S. Kagami ◽  
S. Tsutsumi
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Experimental Studies ◽  
Rolling Resistance ◽  
Leading Edge ◽  
Forward Direction ◽  
Contact Pressure Distribution ◽  
Support Ring ◽  
One Dimensional ◽  
Lowered Pressure

Abstract The contact pressure distribution and the rolling resistance of a running radial tire under load are fundamental properties of the tire construction, important to the steering performance of automobiles, as is well known. Many theoretical and experimental studies have been previously published on these tire properties. However, the relationships between tire performances in service and tire structural properties have not been clarified sufficiently due to analytical and experimental difficulties. In this paper, establishing a spring support ring model made of a composite belt ring and a Voigt type viscoelastic spring system of the sidewall and the tread rubber, we analyze the one-dimensional contact pressure distribution of a running tire at speeds of up to 60 km/h. The predicted distribution of the contact pressure under appropriate values of damping coefficients of rubber is shown to be in good agreement with experimental results. It is confirmed by this study that increasing velocity causes the pressure to rise at the leading edge of the contact patch, accompanied by the lowered pressure at the trailing edge, and further a slight movement of the contact area in the forward direction.

Analysis of the Contact Deformation of a Radial Tire with Camber Angle

1995 ◽  
Vol 23 (1) ◽  
pp. 26-51 ◽  
Author(s):  
S. Kagami ◽  
T. Akasaka ◽  
H. Shiobara ◽  
A. Hasegawa
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Contact Region ◽  
Contact Deformation ◽  
Contact Pressure Distribution ◽  
Radial Tire ◽  
Ring Model ◽  
Camber Angle ◽  
Contact Free ◽  
Good Agreement

Abstract The contact deformation of a radial tire with a camber angle, has been an important problem closely related to the cornering characteristics of radial tires. The analysis of this problem has been considered to be so difficult mathematically in describing the asymmetric deformation of a radial tire contacting with the roadway, that few papers have been published. In this paper, we present an analytical approach to this problem by using a spring bedded ring model consisting of sidewall spring systems in the radial, the lateral, and the circumferential directions and a spring bed of the tread rubber, together with a ring strip of the composite belt. Analytical solutions for each belt deformation in the contact and the contact-free regions are connected by appropriate boundary conditions at both ends. Galerkin's method is used for solving the additional deflection function defined in the contact region. This function plays an important role in determining the contact pressure distribution. Numerical calculations and experiments are conducted for a radial tire of 175SR14. Good agreement between the predicted and the measured results was obtained for two dimensional contact pressure distribution and the camber thrust characterized by the camber angle.

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