Observations of Fatigue Damage in the Press-Fitted Shaft under Bending Loads

2006 ◽  
Vol 326-328 ◽  
pp. 1071-1074 ◽  
Author(s):  
Dong Hyung Lee ◽  
Seok Jin Kwon ◽  
Jae Boong Choi ◽  
Young Jin Kim
Keyword(s):  
Fatigue Damage ◽  
Fatigue Cracks ◽  
Surface Profile ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Fretting Wear ◽  
Multiple Cracks ◽  
Test Machine ◽  
Edge Region ◽  
Fretting Damage

In this paper, the characterization of fretting damage on press-fitted specimens is proposed by experimental methods. A series of fatigue tests and interrupted fatigue tests on pressfitted specimens were carried out by using a rotate bending fatigue test machine. Macroscopic and microscopic characteristics were observed to identify fretting damage mechanism with a scanning electron microscope (SEM) and profilometer. The mechanism of fretting fatigue damage on pressfitted structure is discussed from experimental results. It is found that small cracks of 30~40m in depth are initiated when the specimen reached about 10% of the total life, and thus almost 90% of the fretting fatigue life of press fits can be considered to be in the crack propagation phase. Most of fatigue cracks are initiated at 1050m inner side of contact edge, and multiple cracks are nucleated and interconnected in the fretted surface. The crack nucleation angle in the near contact edge region is larger than that in the inside of the contact edge region. The fretting wear increased with increasing fatigue cycle. Since the fretting wear is relevant to the evolution of surface profile, the fretting fatigue is observed to be closely related with the fretting wear.

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.

The Evolution of Surface Damage in Press-Fitted Shaft According to the Bending Stress

2007 ◽  
Vol 26-28 ◽  
pp. 1353-1356
Author(s):  
Dong Hyung Lee ◽  
Seok Jin Kwon ◽  
Jae Boong Choi ◽  
Young Jin Kim
Keyword(s):  
Fatigue Life ◽  
Surface Damage ◽  
Fatigue Tests ◽  
Fretting Wear ◽  
Small Scale ◽  
Multiple Cracks ◽  
Bending Stress ◽  
Propagation Process ◽  
Fatigue Crack Nucleation ◽  
Bending Load

Fretting damage is a critical problem to prevent failure of press-fitted shaft such as the rotor of a steam turbine, railway axles or coupling. To clarify the characteristics of surface damage due to fretting in press-fitted shaft, experimental methods were applied to small-scale specimen with different bending load conditions. Fatigue tests and interrupted fatigue tests of press-fitted specimen were carried out by using a rotate bending fatigue test machine. Macroscopic and microscopic characteristics were examined using scanning electron microscope (SEM), optical microscope or profilometer. It is found that small fatigue cracks are nucleated early in life regardless of bending stress, and thus the most portion of fatigue life on press fits can be considered to be crack propagation process. Most of surface cracks are initiated near the contact edge, and multiple cracks are nucleated and interconnected. Furthermore, the fretting wear rates at the contact edge increase rapidly at the initial stage of total fatigue life. It is thus suggested that the fatigue crack nucleation and propagation process is strongly related to the evolution of surface profile by fretting wear in press fits.

Using a Dovetail Fixture to Study Fretting Fatigue and Fretting Palliatives

2003 ◽  
Vol 128 (2) ◽  
pp. 133-141 ◽  
Author(s):  
B. P. Conner ◽  
T. Nicholas
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Fatigue Damage ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Turbine Engines ◽  
Aluminum Bronze ◽  
Gas Turbine Engines ◽  
Contact Loads ◽  
Low Plasticity Burnishing

Fretting fatigue damage can reduce the service life of engineering components in contact. The attachment between blades and disks in the fan and compressor stages of gas turbine engines is often a dovetail geometry. As a result, normal and tangential cyclic contact loads are present. Results of fretting fatigue tests using a new dovetail fixture are detailed here. Dovetail specimens and three types of contact pads were all machined out of Ti−6A1−4V. Two types of palliatives are also examined: aluminum bronze coatings and low-plasticity burnishing. While the palliatives were effective in increasing the fatigue life, the three pad geometries produced essentially the same fatigue life.

Fretting Fatigue Phenomena on an all Aluminium Alloy Conductor

2007 ◽  
Vol 348-349 ◽  
pp. 5-8 ◽  
Author(s):  
Marco Boniardi ◽  
Silvia Cincera ◽  
Fabrizio D'Errico ◽  
Chiara Tagliabue
Keyword(s):  
Transmission Line ◽  
Fretting Fatigue ◽  
International Standards ◽  
Fretting Wear ◽  
Limiting Factor ◽  
Fatigue Wear ◽  
Overhead Transmission Line ◽  
Aluminium Wire ◽  
Fretting Damage ◽  
Electrical Conductors

This paper concerns about a failure analysis of an electric all aluminum alloy conductor (AAAC) damaged and broken for fretting fatigue phenomena induced by aeolian vibrations. Life of electric conductors is often reduced by various degradation mechanisms such as repeated bending, fluctuating tension, distortion, fatigue, wear and corrosion phenomena. However the main limiting factor of the electrical conductors is related to aeolian vibrations in the high frequency range (between 5 to 50 Hz). Conductor oscillations may lead to fretting fatigue problems (otherwise called fretting wear) caused by wind excitation, mainly in the suspension clamp regions, spacers or other fittings. The induced aluminium wire fracture imply a drastic reduction in the transmission line service. Vibration dampers are considered the most effective method to extend service life of electric conductors, as they are the means to reduce fretting damage of aluminium wires. The aim of the present work is to investigate the failure of an AAAC conductor of a 400kV overhead transmission line (twin conductors) located in Touggourt Biskra (Algeria); the damaged and broken conductors were operated in-service only for six months without spacers or dampers. Three different types of conductors have been taken as experimental samples: the in-service broken conductor, another in-service damaged conductor and a new conductor from warehouse as terms of comparison. Samples have been analysed to identify the root cause of the failure and to verify the conformity of the conductor elements to the international standards. The investigation has outlined the morphology of the fretting damage: in all cases the fractured wires have shown typical static deformation marks and dynamic fretting wear tangential marks associated with intense presence of Al2O3 debris.

scholarly journals Fretting Fatigue Experiment and Finite Element Analysis for Dovetail Specimen at High Temperature

2021 ◽  
Vol 11 (21) ◽  
pp. 9913
Author(s):  
Zhen Qu ◽  
Kaicheng Liu ◽  
Baizhi Wang ◽  
Zhiying Chen
Keyword(s):  
Finite Element ◽  
Contact Surface ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fretting Fatigue ◽  
Fretting Wear ◽  
Element Analysis ◽  
Centrifugal Load ◽  
Maximum Contact

The dovetail attachment between the turbine blade and disk for an aero-engine operates under varying centrifugal load and vibration at elevated temperatures. The fretting fatigue is prone to occur at the contact surface of the dovetail attachment. This paper investigated the fretting fatigue behavior of the dovetail specimen at 630 °C through experiment and numerical simulation, in which the blade-like dovetail specimen is nickel-based single crystal superalloy DD10 while two fretting pads in contact with the dovetail specimen simulating the mortise of the disk are made of powder metallurgy FGH99. It is revealed from all the tests that the fracture induced by the fretting wear occurs at the upper edge area of the contact surface. The contact surface near the upper edge is more severely worn; hence, the phenomenon of partition on the worn contact surface can be observed, which is consistent with the fretting fatigue mechanism. Moreover, the calculated area of maximum contact pressure gradient through finite element method is in good agreement with the experimental position of the initial fretting fatigue cracks.

A Statistically Based Investigation of the Environmental and Cyclic Stress Effects on Fretting Fatigue

1981 ◽  
Vol 103 (3) ◽  
pp. 218-222 ◽  
Author(s):  
C. J. Poon ◽  
D. W. Hoeppner
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Behavior ◽  
Fretting Fatigue ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Stress Effects ◽  
Mechanics Concepts ◽  
Fractographic Features ◽  
Fretting Damage ◽  
Significant Factors

A completely randomized factorial experiment was conducted to investigate the environmental and cyclic stress effects on the fretting fatigue behavior of 7075-T6 aluminum alloy. Fretting fatigue tests were conducted in vacuum (10−5 Torr) and in laboratory air environment at two maximum cyclic stress levels. The fractographic features of the wear surface with respect to different environments were examined. The experimental results and statistical analysis showed that the environment, cyclic stress, and their interactions were significant factors in reducing the life of 7075-T6 aluminum alloy under fretting conditions. The fractographic analysis showed that fretting damage led to the development of cracks in the fretting areas in both environments. However, the mechanisms involved in crack development were different. The reduction in fatigue life under fretting condition was explained by a model utilizing fracture mechanics concepts.

A Probabilistic Fatigue Damage Model for Describing the Entire Set of Fatigue Test Data of the Same Material

2019 ◽  
Author(s):  
Xiaobin Le
Keyword(s):  
Fatigue Test ◽  
Fatigue Damage ◽  
Test Data ◽  
Stress Level ◽  
Damage Model ◽  
Fatigue Tests ◽  
Small Sample ◽  
Test Machine ◽  
Stress Levels ◽  
D Model

Abstract One typical widely-accepted approach for describing the fatigue test data is the P-S-N curve approach. However, the P-S-N curve approach has some issues such as: (1) If there are only a few fatigue test data at a fatigue test stress level, the P-S-N curve approach is not valid due to the small sample size; (2) When the total number of fatigue tests under different stress levels might be larger such as more than 30 even though the number of fatigue tests at the same stress level is small, the P-S-N curve cannot be used to analyze such set of fatigue data; (3) It is difficult to calculate the reliability of a component under a cyclic stress level when the probabilistic distribution function under this stress level is not available in the P-S-N curves. The author has proposed the K-D probabilistic fatigue damage model (K-D model) to overcome those issues. The 6061-T6 10-gauge sheet-type flat fatigue specimen was designed, manufactured, and tested on the Instron 8081 fatigue test machine to verify this K-D model. The fatigue tests were under five different cyclic axial loadings with a total of 195 tests. In this paper, the fatigue test data will be analyzed by the P-S-N curve approach and the K-D model. The systematic comparisons between the P-S-N curve approach and the K-D model have approved and verified that the K-D model can be used to analyze and to describe the fatigue test data under all different fatigue stress levels and can be used to calculate the reliability of a component under any type of cyclic fatigue loading.

A Probabilistic Fatigue Damage Model for Aluminum 6061-T6 10-Gauge Sheet-Type Material

2021 ◽  
Author(s):  
Xiaobin Le
Keyword(s):  
Fatigue Test ◽  
Fatigue Damage ◽  
Cyclic Load ◽  
Damage Model ◽  
Fatigue Tests ◽  
Load Level ◽  
Cyclic Loads ◽  
Test Machine ◽  
Axial Loads ◽  
Fatigue Specimen

Abstract The 6061-T6 10-gauge sheet-type flat fatigue specimen was designed, manufactured, and tested on an Instron 8081 fatigue test machine. The fatigue tests were performed under five different cyclic axial loads with 195 tests. This paper will display how to use these 195 test data under different cyclic axial loads to build a probabilistic fatigue damage model. The model is validated by the results obtained from the traditional P-S-N curve approach. One advantage of this probabilistic fatigue damage model is that it can calculate the reliability of a component under any type of cyclic loads at any cyclic load level.

A STUDY ON FRETTING BEHAVIOR IN ROOM TEMPERATURE FOR INCONEL ALLOY 690

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4303-4308 ◽  
Author(s):  
JAE DO KWON ◽  
YOUNG SUCK CHAI ◽  
YONG TAK BAE ◽  
SUNG JONG CHOI
Keyword(s):  
Fatigue Strength ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Fatigue Behavior ◽  
Aqueous Media ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Inconel Alloy ◽  
Alloy 690 ◽  
Fretting Damage

The initial crack under fretting condition occurs at lower stress amplitude and lower cycles of cyclic loading than that under plain fatigue condition. The fretting damage, for example, can be observed in fossil and nuclear power plant, aircraft, automobile and petroleum chemical plants etc. INCONEL alloy 690 is a high-chromium nickel alloy having excellent resistance to many corrosive aqueous media and high-temperature atmospheres. This alloy is used extensively in the industries of nuclear power, chemicals, heat-treatment and electronics. In this paper, the effect of fretting damage on fatigue behavior for INCONEL alloy 690 was studied. Also, various kinds of tests on mechanical properties such as hardness, tension and plain fatigue tests are performed. Fretting fatigue tests were carried out with flat-flat contact configuration using a bridge type contact pad and plate type specimen. Through these experiments, it is found that the fretting fatigue strength decreased about 43% compared to the plain fatigue strength. In fretting fatigue, the wear debris is observed on the contact surface, and the oblique micro-cracks are initiated at an earlier stage. These results can be used as the basic data in a structural integrity evaluation of heat and corrosion resistant alloy considering fretting damages.

scholarly journals Influence of Ultrasonic Surface Rolling Process and Shot Peening on Fretting Fatigue Performance of Ti-6Al-4V

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Ning Wang ◽  
Jinlong Zhu ◽  
Bai Liu ◽  
Xiancheng Zhang ◽  
Jiamin Zhang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Compressive Stress ◽  
Shot Peening ◽  
Fatigue Cracks ◽  
Rolling Process ◽  
Fretting Fatigue ◽  
Fretting Wear ◽  
Surface Strengthening ◽  
Maximum Value

AbstractAt present, there are many studies on the residual stress field and plastic strain field introduced by surface strengthening, which can well hinder the initiation of early fatigue cracks and delay the propagation of fatigue cracks. However, there are few studies on the effects of these key factors on fretting wear. In the paper, shot-peening (SP) and ultrasonic surface rolling process (USRP) were performed on Ti-6Al-4V plate specimens. The surface hardness and residual stresses of the material were tested by vickers indenter and X-ray diffraction residual stress analyzer. Microhardness were measured by HXD-1000MC/CD micro Vickers hardness tester. The effects of different surface strengthening on its fretting fatigue properties were verified by fretting fatigue experiments. The fretting fatigue fracture surface and wear morphology of the specimens were studied and analyzed by means of microscopic observation, and the mechanism of improving fretting fatigue life by surface strengthening process was further explained. After USRP treatment, the surface roughness of Ti-6Al-4V is significantly improved. In addition, the microhardness of the specimen after SP reaches the maximum at 80 μm from the surface, which is about 123% higher than that of the AsR specimen. After USRP, it reaches the maximum at 150 μm from the surface, which is about 128% higher than that of AsR specimen. It is also found that the residual compressive stress of the specimens treated by USRP and SP increases first and then decreases with the depth direction, and the residual stress reaches the maximum on the sub surface. The USRP specimen reaches the maximum value at 0.18 mm, about − 550 MPa, while the SP specimen reaches the maximum value at 0.1 mm, about − 380 MPa. The fretting fatigue life of Ti-6Al-4V effectively improved after USRP and SP. The surface integrity of specimens after USRP is the best, which has deeper residual compressive stress layer and more refined grain. In this paper, a fretting wear device is designed to carry out fretting fatigue experiments on specimens with different surface strengthening.

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