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.

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.

scholarly journals Fretting wear rate of sulphur deficient MoSx coatings based on dissipated energy

2001 ◽  
Vol 16 (12) ◽  
pp. 3567-3574 ◽  
Author(s):  
Xiaoling Zhang ◽  
W. Lauwerens ◽  
L. Stals ◽  
Jiawen He ◽  
J-P. Celis
Keyword(s):  
Relative Humidity ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Contact Stress ◽  
Ambient Air ◽  
Fretting Wear ◽  
Dissipated Energy ◽  
Wear Volume ◽  
The Coefficient Of Friction ◽  
Crystallographic Orientations

The fretting wear of sulphur-deficient MoSx coatings with different crystallographic orientations has been investigated in ambient air of controlled relative humidity. The coefficient of friction and the wear rate of MoSx coatings sliding against corundum depend not only on fretting parameters like contact stress, fretting frequency, and relative humidity, but also strongly on the crystallographic orientation of the coatings. For randomly oriented MoSx coatings, the coefficient of friction and the wear rate increased significantly with increasing relative humidity. In contrast, basal-oriented MoSx coatings were less sensitive to relative humidity. The coefficient of friction of both types of MoSx coatings decreased on sliding against corundum with increasing contact stress and decreasing fretting frequency. A correlation between dissipated energy and wear volume is proposed. This approach allows detection in a simple way of differences in fretting wear resistance between random- and basal-oriented MoSx coatings tested in ambient air of different relative humidity.

Characteristics of Fretting Wear in a Press-Fitted Shaft Subjected to Bending Load

2010 ◽  
Vol 97-101 ◽  
pp. 1269-1272 ◽  
Author(s):  
Dong Hyung Lee ◽  
Seok Jin Kwon ◽  
Won Hee You
Keyword(s):  
Fatigue Life ◽  
Wear Rate ◽  
Contact Surface ◽  
Early Stage ◽  
Load Condition ◽  
Surface Profile ◽  
Fretting Wear ◽  
Test Machine ◽  
Wear Coefficient ◽  
Bending Load

This paper presents the results of an experimental investigation of fretting wear characteristics on the contact surface of press-fitted shaft subjected to a cyclic bending load. A series of interrupted fretting wear tests with press-fitted specimens were carried out by using a rotating bending fatigue test machine. The evolution of contact surface profile of press-fitted shaft due to fretting wear were measured with a profilometer. The local wear coefficient during the running-in period is discussed from experimental results and FE analysis. It is found that the maximum depth of fretting wear by repeated slip between shaft and boss occurred at the close of contact edge at the early stage of fatigue life and the regions of worn surface are expanded to the inner side of contact edge as increasing number of fatigue cycles. The initial fretting wear rate at the early stage of fatigue life increased rapidly at all loading condition. After steep increasing, the increase of wear rate is nearly constant in the low bending load condition. The local wear coefficient in running-in period decrease dramatically at the early stage of fretting wear.

scholarly journals Wear Analysis of a Low-Speed Diesel Engine Connecting Rod Based on Orthogonal Simulation Test

2021 ◽  
Vol 2093 (1) ◽  
pp. 012014
Author(s):  
Wasim M. K. Helal ◽  
Wenping Zhang ◽  
Xiaobo Li ◽  
Guixin Wang ◽  
Yanpan Su
Keyword(s):  
Diesel Engine ◽  
Friction Coefficient ◽  
Contact Pressure ◽  
Contact Surface ◽  
Contact Process ◽  
Friction Stress ◽  
Fretting Wear ◽  
Pressure Condition ◽  
Simulation Test ◽  
Combustion Pressure

Abstract As con-rod is a critical component in an engine, its reliability overwhelmingly directly affects the performance of the whole diesel engine. The fretting wear of con-rod bushing mainly occurs on the contact surface with con-rod small end and con-rod small end cap. In the proposed study, the contact process of con-rod small end, con-rod small end cap and bushing under maximum combustion pressure condition was analyzed, and the distribution of contact pressure and friction stress was analyzed. Then the orthogonal simulation test was designed. According to the contact mechanics theory, the interference amount and friction coefficient of the contact surface were taken as the test factors, and the maximum contact pressure and friction stress under the maximum combustion pressure condition were taken as the objective functions. The influence of the test factors on the objective function was analyzed, and the most reasonable interference amount and friction coefficient were found, so as to slow down the fretting wear of the con-rod bushing.

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.

scholarly journals Effect of contact pressure on fretting fatigue strength.

1987 ◽  
Vol 53 (486) ◽  
pp. 196-199 ◽  
Author(s):  
Kohsoku NAGATA ◽  
Takeshi MATSUDA ◽  
Hideo KASHIWAYA
Keyword(s):  
Fatigue Strength ◽  
Contact Pressure ◽  
Fretting Fatigue
Sign in / Sign up

Export Citation Format

Share Document