A Study on Improvement of Fatigue Life of materials by Surface Coatings

Fatigue failure is one of the main reasons for the mechanical failure in engineering materials. To improve the fatigue strength of the material one of the most used method is heat treatment of the materials in which hardness, wear resistance and aesthetics is improved. Of late, the complexity of predicting fatigue life of engineering components is increasing exponentially due to the varied and multi-facet loading conditions, complex geometries, and newer materials coming up in the market. In this paper the the quantitative measurement of the influence of Annealing on the fatigue life of SS 304 steels. Theresults conculed clearly clearly that there is a definite improvement in the fatigue life due to Annealing in steel. However the extent of improvement in fatigue life was more in SS 304 (after annealing) when compared to SS 304(before annealing).

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Comparison of Fatigue Life Cycle of Different Aluminium Alloy AA 5083 - AA6062

International Journal of Scientific Research in Science Engineering and Technology ◽

10.32628/ijsrset196364 ◽

2019 ◽

pp. 283-288

Author(s):

Sunit Yadav ◽

Kamal Kanaujia ◽

Ravi Shukla

Keyword(s):

Wear Resistance ◽

Fatigue Crack ◽

Life Cycle ◽

Fatigue Life ◽

Fatigue Strength ◽

Comparative Study ◽

Aluminium Alloy ◽

Fatigue Testing ◽

Mode I ◽

Loading Mode

Fatigue failure is one of the main reasons for the mechanical failure in engineering materials. To improve the fatigue strength of the material one of the most used method is surface treatment of the materials in which hardness, wear resistance and aesthetics is improved. In this paper a comparative study of fatigue of two different aluminium alloy [AA 5083-AA6062] was conducted. CT specimen of both the alloys was formed as per ASTM-E647 Standard. The result shows that the fatigue life of AA5083 greater than AA6062. In this paper fracture that occur in material during fatigue testing and effect of fatigue life on material is studied. The main purpose of the research presented herein was to study the fatigue crack propagation under loading mode I.

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Fatigue Life Improvement of Welded Elements and Structures by Ultrasonic Impact Treatment

Volume 3: Materials Technology; Jan Vugts Symposium on Design Methodology of Offshore Structures; Jo Pinkster Symposium on Second Order Wave Drift Forces on Floating Structures; Johan Wichers Symposium on Mooring of Floating Structures in Waves ◽

10.1115/omae2011-50310 ◽

2011 ◽

Author(s):

Yuriy Kudryavtsev ◽

Jacob Kleiman

Keyword(s):

Mechanical Properties ◽

Fatigue Life ◽

Fatigue Strength ◽

Residual Stresses ◽

Fatigue Testing ◽

Highway Bridges ◽

Surface Layers ◽

Ultrasonic Impact Treatment ◽

Stress Relieving ◽

Life Improvement

The ultrasonic impact treatment (UIT) is relatively new and promising process for fatigue life improvement of welded elements and structures. In most industrial applications this process is known as ultrasonic peening (UP). The beneficial effect of UIT/UP is achieved mainly by relieving of harmful tensile residual stresses and introducing of compressive residual stresses into surface layers of a material, decreasing of stress concentration in weld toe zones and enhancement of mechanical properties of the surface layers of the material. The UP technique is based on the combined effect of high frequency impacts of special strikers and ultrasonic oscillations in treated material. Fatigue testing of welded specimens showed that UP is the most efficient improvement treatment as compared with traditional techniques such as grinding, TIG-dressing, heat treatment, hammer peening and application of LTT electrodes. The developed computerized complex for UP was successfully applied for increasing the fatigue life and corrosion resistance of welded elements, elimination of distortions caused by welding and other technological processes, residual stress relieving, increasing of the hardness of the surface of materials. The UP could be effectively applied for fatigue life improvement during manufacturing, rehabilitation and repair of welded elements and structures. The areas/industries where the UP process was applied successfully include: Shipbuilding, Railway and Highway Bridges, Construction Equipment, Mining, Automotive, Aerospace. The results of fatigue testing of welded elements in as-welded condition and after application of UP are considered in this paper. It is shown that UP is the most effective and economic technique for increasing of fatigue strength of welded elements in materials of different strength. These results also show a strong tendency of increasing of fatigue strength of welded elements after application of UP with the increase in mechanical properties of the material used.

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Effect of Laser Preheating AISI 4140 Specimens for Micro-Forging

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0179 ◽

2017 ◽

Vol 62 (2) ◽

pp. 1209-1213

Author(s):

C. Jung ◽

M.G. Lee ◽

Y. Jeon

Keyword(s):

Heat Treatment ◽

Fatigue Life ◽

Fatigue Strength ◽

Surface Treatment ◽

Laser Heat Treatment ◽

Forging Process ◽

Advantages And Disadvantages ◽

Treatment Processes ◽

Laser Heat ◽

Aisi 4140

Abstract Many high performance and permanent service parts require suitable material characteristics-high fatigue strength is one of the most important characteristics. For this reason, surface treatment processes are essential to increase the material performance and avoid the use of costly ineffective material. There exist various surface treatment processes for various applications. Each process has advantages and disadvantages and hybridization can solve various problems. The micro-forging process delivers a controlled and uniform surface hardness, but the depth of the forged surface is limited. On the other hand, laser heat treatment can increase the hardness drastically, but the surface may become brittle, which reduces the fatigue life. Laser-assisted micro-forging is a novel hybrid process of laser heat treatment and micro-forging that has the potential to increase the forging depth and relax the stress caused by the high temperature of the forging process. This study examines the effect of laser preheating in the micro-forging of AISI 4140. The processes were varied as follows: no treatment, micro-forging only, and laser-assisted micro-forging. The fatigue strength of the specimens was examined by means of an ultrasonic fatigue tester and then compared. The microstructural changes were investigated with respect to the processes by using scanning electron microscopy. In conclusion, it was confirmed that the laser preheating auxiliary forging affects the fatigue life. It was confirmed that the fatigue life was the mostly increased in 550°C temperature laser preheating micro forging process and the temperature was identified as the most important factor.

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Fatigue improvement of welded elements by ultrasonic impact treatment

Zavarivanje i zavarene konstrukcije ◽

10.5937/zzk2004179k ◽

2020 ◽

Vol 65 (4) ◽

pp. 179-190

Author(s):

Yuir Kudryavtsev

Keyword(s):

Mechanical Properties ◽

Fatigue Life ◽

Fatigue Strength ◽

Residual Stresses ◽

Large Scale ◽

Fatigue Testing ◽

Fatigue Improvement ◽

Surface Layers ◽

Ultrasonic Impact Treatment ◽

Stress Relieving

The ultrasonic impact treatment (UIT) is relatively new and promising process for fatigue life improvement of welded elements and structures. In most industrial applications this process is known as ultrasonic peening (UP). The beneficial effect of UIT/UP is achieved mainly by relieving of tensile residual stresses and introducing of compressive residual stresses into surface layers of a material. The secondary factors in fatigue improvement by UIT/UP are decreasing of stress concentration in weld toe zones and enhancement of mechanical properties of the surface layers of the material. Fatigue testing of welded specimens showed that UIT/UP is the most efficient improvement treatment as compared with traditional techniques such as grinding, TIG-dressing, heat treatment, hammer peening and application of LTT electrodes. The developed computerized complex for UIT/UP was successfully applied for increasing the fatigue life and corrosion resistance of welded elements, elimination of distortions caused by welding and other technological processes, residual stress relieving, increasing of the hardness of the surface of materials. The results of fatigue testing of large-scale welded specimens in as-welded condition and after application of UIT/UP are considered in this paper. It is shown that UIT/UP is the most effective and economic technique for increasing of fatigue strength of welded elements in materials of different strength. These results also show a strong tendency of increasing of fatigue strength of welded elements after application of UP with the increase in mechanical properties of the material used.

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EFFECT OF FATIGUE TEST ON SPOT WELDED STRUCTURAL JOINT

Jurnal Teknologi ◽

10.11113/jt.v79.11290 ◽

2017 ◽

Vol 79 (5-2) ◽

Author(s):

Mohammad Khalid Wahid ◽

Muhammad Nabil Muhammed Sufian ◽

Mohamed Saiful Firdaus Hussin

Keyword(s):

Life Cycle ◽

Fatigue Life ◽

Fatigue Strength ◽

Spot Welding ◽

Fatigue Testing ◽

Fatigue Stress ◽

Component Design ◽

Welded Structure ◽

Different Thickness ◽

Spot Welded

Spot welding is mainly used method in joining sheet metals for body structure in automotive industry. The comprehension of the fatigue strength for the spot welds is very critical in automotive component design. Parameter for the resistance spot welding and fatigue machines is constant for each specimen used. The S-N curve is obtained from the fatigue testing for each specimen. This experiment parameters are varies the different thickness and different material combination in spot welding structure to investigate the fatigue life cycle and fatigue stress. For 1050A aluminium joint, fatigue life cycle and fatigue strength will decrease from number of cycle 500 at 16.58 MPa to number of cycle 61 at 6.62 MPa as the thickness increase. The fatigue life cycle and fatigue stress for galvanized iron will increase from number of cycle 46 at 9.25 MPa to number of cycle 1500 at 57.8 MPa when the thickness of joint increase. The finding from the combination of 1050A aluminum and galvanized iron on spot welded structure has shown no improvement in term of fatigue life cycle and fatigue strength because specimens experienced failure at number of cycle 19 with fatigue stress 2.36 MPa.

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Fatigue Improvement of Welded Elements and Structures by Ultrasonic Peening

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2013-97185 ◽

2013 ◽

Cited By ~ 5

Author(s):

Yuri Kudryavtsev ◽

Jacob Kleiman

Keyword(s):

Mechanical Properties ◽

Fatigue Life ◽

Fatigue Strength ◽

Residual Stresses ◽

Fatigue Testing ◽

Fatigue Improvement ◽

Surface Layers ◽

Ultrasonic Peening ◽

Stress Relieving ◽

Life Improvement

The ultrasonic impact treatment (UIT) is relatively new and promising process for fatigue life improvement of welded elements and structures. In most industrial applications this process is known as ultrasonic peening (UP). The beneficial effect of UP is achieved mainly by relieving of tensile residual stresses and introducing of compressive residual stresses into surface layers of a material. The secondary factors in fatigue improvement by UP are decreasing of stress concentration in weld toe zones and enhancement of mechanical properties of the surface layers of the material. Fatigue testing of welded specimens showed that UP is the most efficient improvement treatment as compared with traditional techniques such as grinding, TIG-dressing, heat treatment, hammer peening and application of LTT electrodes. The developed computerized complex for UP was successfully applied for increasing the fatigue life and corrosion resistance of welded elements, elimination of distortions caused by welding and other technological processes, residual stress relieving, increasing of the hardness of the surface of materials. The UP could be effectively applied for fatigue life improvement during manufacturing, rehabilitation and repair of welded elements and structures. The areas/industries where the UP process was applied successfully include: Shipbuilding, Railway and Highway Bridges, Construction Equipment, Mining, Automotive, Aerospace. The results of fatigue testing of welded elements in as-welded condition and after application of UP are considered in this paper. It is shown that UP is the most effective and economic technique for increasing of fatigue strength of welded elements in materials of different strength. These results also show a strong tendency of increasing of fatigue strength of welded elements after application of UP with the increase in mechanical properties of the material used.

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Propagation of Contact Fatigue From Surface and Subsurface Origins

Journal of Basic Engineering ◽

10.1115/1.3645922 ◽

1966 ◽

Vol 88 (3) ◽

pp. 624-635 ◽

Cited By ~ 83

Author(s):

W. E. Littmann ◽

R. L. Widner

Keyword(s):

Fatigue Life ◽

Fatigue Strength ◽

Fatigue Failure ◽

Contact Stress ◽

Environmental Conditions ◽

Failure Modes ◽

Contact Fatigue ◽

Initiation And Propagation ◽

Tapered Roller ◽

Tapered Roller Bearings

Fatigue life of tapered roller bearings and other elements subject to cyclic contact stress reflects the fatigue strength of the selected material under given environmental conditions. The various modes of contact-fatigue failure have been classified according to their appearance and the factors which promote their initiation and propagation. Illustrations of the various failure modes include rig test specimens and bearings representing normal catalog-rated life under laboratory and application environments. Evidence is presented for the propagation of contact fatigue from surface and subsurface origins.

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3D Computational Simulation of Multi-Impact Shot Peening

MRS Proceedings ◽

10.1557/opl.2013.210 ◽

2012 ◽

Vol 1485 ◽

pp. 35-40

Author(s):

Juan Solórzano-López ◽

Francisco Alfredo García-Pastor

Keyword(s):

Residual Stress ◽

Fatigue Life ◽

Stress Field ◽

Surface Treatment ◽

Shot Peening ◽

Compressive Residual Stress ◽

Fatigue Testing ◽

Computational Simulation ◽

Target Material ◽

Residual Stress Field

ABSTRACTShot peening is a widely applied surface treatment in a number of manufacturing processes in several industries including automotive, mechanical and aeronautical. This surface treatment is used with the aim of increasing surface toughness and extending fatigue life. The increased performance during fatigue testing of the peened components is mainly the result of the sub-surface compressive residual stress field resulting from the plastic deformation of the surface layers of the target material, caused by the high-velocity impact of the shot. This compressive residual stress field hinders the propagation and coalescence of cracks during the second stage of fatigue testing, effectively increasing the fatigue life well beyond the expected life of a non-peened component.This paper describes a 3D computational model of spherical projectiles impacting simultaneously upon a flat surface. The multi-impact model was developed in ABAQUS/Explicit using finite element method (FEM) and taking into account controlling parameters such as the velocity of the projectiles, their incidence angle and different impact locations in the target surface. Additionally, a parametric study of the physical properties of the target material was carried out in order to assess the effect of temperature on the residual stress field.The simulation has been able to successfully represent a multi-impact processing scenario, showing the indentation caused by each individual shot, as well as the residual stress field for each impact and the interaction between each one of them. It has been found that there is a beneficial effect on the residual stress field magnitude when shot peening is carried out at a relatively high temperature. The results are discussed in terms of the current shot-peening practice in the local industry and the leading edge developments of new peening technologies. Finally, an improved and affordable processing route to increase the fatigue life of automotive components is suggested.

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A Study of Fatigue-Life Estimation and Reliability Analysis for Dental Implants

Volume 5: 6th International Conference on Micro- and Nanosystems; 17th Design for Manufacturing and the Life Cycle Conference ◽

10.1115/detc2012-70138 ◽

2012 ◽

Author(s):

Yuo-Tern Tsai ◽

Y. K. Lu ◽

Y. Y. Hsu ◽

J. B. Lu

Keyword(s):

Experimental Data ◽

Fatigue Life ◽

Fatigue Strength ◽

Dental Implants ◽

Fatigue Testing ◽

Simulation Analysis ◽

Linear Regression Method ◽

Estimation Model ◽

Life Estimation ◽

Fatigue Life Estimation

Recently, dental implants (DIs) are extensively utilized on edentulous patients. The bio-compatibility & physical properties of DIs are severely specified since it belongs to the products of biomedicine. Generally, DIs must pass a series of tests before they are approved to use in human body. In this paper, a method of probabilistic fatigue-life estimation was proposed to fulfill reliability life prediction of DIs. The probabilistic form of fatigue-life evaluation is developed based on material constants namely fatigue strength coefficient and fatigue strength exponent. The procedure is developed based on the shift of the fatigue-life curve to the desired value of the probability of occurrence. This estimation model yields the life distribution in respect of the scatter of the cyclic properties of DIs. The CAD models of DIs are first constructed to perform computer simulation analysis for establishing the fracture spots. The stress analysis and life estimation were carried out by ANSYS software. The simulation results are further compared with the experimental data obtained by fatigue testing to determine the estimated model of fatigue life. The parameters of the model were determined by linear regression method based on the combination of the simulated and experimental data. The reliabilities of DIs were further investigated to provide an index of life-safety of DI at different cyclic loads. The analyzed results may be useful while programming the fatigue testing of DIs.

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