Rotating Bending Fatigue Testing Machine Research Articles

Design and manufacturing of rotating bending fatigue test machine

Design and manufacturing of rotating bending fatigue test machine

Kaji Eksperimental Karakteristik Fatik Komposit Polyester Partikulat Al2O3

This research investigates the fatigue characteristics of Al2O3 particulate polyester composite, including fatigue limit, fatigue life, and fracture surface morphology in the test specimens. Fatigue test specimens with variations of Al2O3 filler of 4%, 6%, 8%, and 10% were tested using a rotary bending fatigue testing machine under varying loads to determine the number of cycles until failure. The research results indicate that the polyester composite with 4% and 6% Al2O3 filler had a fatigue limit of 1.9 MPa and could withstand 1.000.000 cycles. Meanwhile, the polyester composite with 8% and 10% Al2O3 filler had a fatigue limit of 0.9 MPa and also endured 1.000.000 cycles. The average fatigue life was 28.957 cycles, 22.725 cycles, 98.572 cycles and 66.352.5 cycles for 4% mass fraction, 6% mass fraction, 8% mass fraction, and 10% mass fraction respectively. The fracture surface morphology of the test specimens varied significantly, mainly due to multiple origins, where multiple initiation points of fracture simultaneously occurred, leading to surface erosion or tearing before the specimen ultimately failed or fractured.

Correction to: Effect of Strain Hardening and Aging Processes on Microstructure Evolution, Tensile and Fatigue Properties of Cast Ti-6Al-2Sn-2Zr–2Mo-1.5Cr-2Nb-0.1Si Alloy

The effect of strain hardening and aging processes on microstructure, tensile and fatigue properties was investigated on cast TC21 samples with a chemical composition of Ti-6.1Al-2.96Mo-2.11Nb-1.98Sn-2.05Zr-1.44Cr-0.1Si. Plastic deformation (strain hardening) was applied on swaged samples at room temperature with 2%, 3% and 4% strain. By applying aging process at 575°C for 4 hr, secondary α-platelets were precipitated in the transformed β-phase. Maximum hardness (HV440) was achieved for 4%def. + aged samples. However, minimum hardness (HV323) was recorded for aged samples. Maximum ultimate tensile strength (1311MPa) and elongation (14%) were obtained for 4% def. + aged samples due to presence of high amount of dislocation density as well as precipitation of secondary α-platelets in the residual β-phase. Minimum ultimate tensile strength (1020MPa) and elongation (3%) were reported for as-cast samples. Theoretical study using ANSYS software program was carried out for estimating fatigue limits for investigated samples. For validating the theoretical results, experimental test was done using rotating bending fatigue testing machine on three selected conditions of swaged, 2%def. + aged and 4%def. + aged. Maximum estimated fatigue strength of 775 MPa was obtained for 4%def. + aged samples, and the experimental one was 755 MPa. Hence, the difference between estimated and experimental fatigue limits for 4%def. + aged samples was less than of 3%.

Failure analysis of cryogenically treated H13 specimen in rotating bending fatigue

The fatigue failures start at the surface mostly in case of forging die steels like AISI H13. The aim of this work is to analyse the effect of cryogenic treatment on delayed failure of H13 steel specimens subjected to rotating bending fatigue. The specimens were hardened at 1020 °C, double tempered at 500 °C for 2 h, followed bycryogenic treatment in a cryo-chamber at minus 185 °C for 16 h and soft tempering at 100 °C. The room temperature fatigue test was carried out on rotating bending fatigue testing machine at 3000 rpm with constant amplitude loading. X-ray diffraction studies were carried out along with microstructural details. It was established that fine grained structure, precipitation of fine carbides in the tempered marten site, increased carbide density and harder structure were responsible for the delayed crack propagation and thereby increasing the fatigue life of the cryogenically treated H13 steel in comparison with the conventionally treated specimens in high cycle fatigue regime.

Effects of Surface Treatment on Fatigue Property of A5052-H14 and A2017-T4 Aluminum Alloys

In this study, the effect of anodization and electroless Ni-P plating on the fatigue strength of commercial A5052-H14 and A2017-T4 aluminum alloys was investigated. The coated aluminum alloys were tested using a rotary bending fatigue testing machine. Anodization led to a slight increase in the fatigue strength of the A2017-T4 alloy of approximately 10％ because of the suppression of the generation of fatigue crack, and anodization with a 5-µm thickness for A5052-H14 also led to a slight increase in the fatigue strength. However, anodization with a 20-µm thickness for A5052-H14 led to reduced fatigue strength because of the pits that formed in the film. In addition, electroless Ni-P plating drastically improved the fatigue strength of the A5052-H14 alloy by suppressing the generation of fatigue crack．It also improved the fatigue strength of the A2017-T4 alloy in the high-stress region. However, the fatigue strength in the low-stress region was the same as that of the non-coated specimens．This fatigue strength should have originated from the hydrogen embrittlement by the hydrogen introduced into the specimen during the plating.

Effect of Carbide Density on Fatigue Limit of H21 Die Steel

In the present work, the effect of carbide density on microstructure, hardness, wear rate, and fatigue limit of AISI H21 die steel has been studied. The specimens of H21 die steel have been employed hardening at 1195 °C, double tempering at 540 °C, cryotreatment at − 185 °C for 24 h, and soft tempering at 100 °C. The microstructure, hardness, wear rate, and fatigue limit of the conventionally treated and cryotreated specimens have been examined. The pin-on-disk machine has been used for the dry sliding wear test. The fatigue test has been carried out using constant amplitude rotating bending fatigue test machine which indicates enhanced fatigue limit for cryotreated specimens. The improvement in hardness, wear behavior, and fatigue limit of cryotreated specimens as a result of increased carbide density with reduced carbide size and retained austenite has been observed. The carbides Fe6W6C, Cr23C6 and Cr7C3 played an important role in increasing the hardness, wear behavior, and fatigue limit of the material. The Basquin’s equation was used for the analysis of the fatigue test. The minimum value of the fatigue strength exponent of Basquin’s equation shows the enhanced fatigue limit of cryotreated specimens.

Testing of the ability of fatigue test machine prototype and fatigue test for nylon and cast iron specimens

Fatigue life prediction for engineering material is important for predictive maintenance to support accident prevention in a high-risk equipment. The study aims to determine the ability of the machine prototype of rotating bending type fatigue test and to find out the fatigue life of Nylon and cast iron specimens. By knowing the fatigue life of a plastic and ferrous metal material, the prediction of fatigue life can be applied to a maintenance plan. The design and manufacture of rotating bending fatigue testing machines equipped with copy turning devices can be used to prepare specimens from plastic/soft metal materials, thus becoming an integrated fatigue test machine. The method used includes determining the standard size of fatigue test specimens, turning various fatigue test specimens, carrying out fatigue test specimens of nylon and cast iron materials, and analyzing the results of fatigue tests. The test results of the fatigue test machine prototype showed the ability to turn plastic and soft metal materials, and the fatigue life for Nylon 6.6 ranging from 659 to 13216 rotation for breaking the specimens at 229 to 26 MPa stresses, and for cast iron from 142 to 22863 rotation at 229 to 147 MPa stresses.

Evaluation of Fatigue Life of Al2024/Al2O3 Particulate Nano Composite Fabricated Using Stir Casting Technique

The main objective of this paper is to carry out a study of effect of nano Al2O3 reinforcement on the fatigue life of aluminum nano metal matrix composite. The reinforcing particulates in the NMMC’s vary from 0% to 2% by weight with an increment of 0.5%. The liquid metallurgy method coupled with powder metallurgy is employed to fabricate the composites, in which the reinforcements are poured into the vortex created by stirring the molten metal by means of mechanical two stage stirrer. The composites so produced are subjected to tensile and fatigue testing. Fatigue tests were conducted on Al2024 and its nano composite on rotary bending fatigue testing machine at five different stress levels. Statistical design of fatigue experiments was carried out to determine the sample size at each stress level. Details of generation of S-N curve for Al2024 and its composite using a regression analysis is delineated. ANOVA is performed in order to check the significance of regression equation. The S-N curve of the aluminum nano composite is compared with its matrix Al2024. Scanning Electron Micrograph (SEM) image of the cast NMMC having highest fatigue life is also taken in order to study the dispersion of reinforcements in the matrix.

Basic study on crack diagnosis of rotary equipment by fluid-mediated AE method

The AE (Acoustic Emission) method is a technique for detecting ultrasonic sound waves generated by plastic deformation, crack initiation and crack growth by using an AE sensor. The AE method is used in checks of petroleum tank drawer bottom corrosion, degradation of steel and concrete structures, bearing degradation checks, etc. The purpose of this study is to apply AE to crack checks of rotary equipment (drive shaft or coupling). First, we conducted a comparative test of AE propagation characteristics, followed by a comparative test of the crack detection signal by a small rotary bending fatigue testing machine. From the AE count rate in the rotary bending fatigue test, the number of cycles of the fatigue test can be divided into three areas. In the initial stage, an AE wave is generated by the dislocation motion in the material. An AE wave is estimated to occur due to the progress of a crack generated on the test piece surface. In this study, we propose a fluid-mediated AE method with an improved S/N ratio and showed that it is possible to detect a fatigue crack in a drive shaft or coupling by the proposed method.

The effect of pure aluminum cold spray coating on corrosion and corrosion fatigue of magnesium (3% Al-1% Zn) extrusion

Pure aluminum powder was successfully sprayed on AZ31B extrusion flat and round coupons at low temperature. The corrosion and corrosion fatigue behavior of the coated and uncoated samples were examined by performing accelerated corrosion tests. The corrosion resistance of AZ31B samples with and without coating was investigated based on ASTM B117 standard salt spray with a concentration of 5% NaCl at 36°C, 100% relative humidity. The corrosion fatigue of bare and coated round samples was examined by producing a thin film of 3.5% NaCl solution on the surface of the fatigue samples via integrating a corrosion chamber into a rotating bending fatigue testing machine. Pure Al coating provided significant corrosion protection for AZ31B in 5% NaCl fog environment by improving its corrosion resistance from 90% average weight loss in 33days for bare samples to <10% average weight loss in 90days of continuous corrosion cycles. However, pure Al coating did not improve the corrosion fatigue strength of magnesium and samples with and without coating showed similar corrosion fatigue trends. Test results in salt solution showed fatigue life reduction of 88% when compared with test results in air. The microstructure examination of samples failed under cyclic load showed early cracking of Al coat which allowed the electrolyte penetration into Mg substrate creating a localized corrosion and premature failure. The early cracking was attributed to the lower fatigue strength of pure Al compared to AZ31B.

Effects of WC-17Co Coating Combined with Shot Peening Treatment on Fatigue Behaviors of TC21 Titanium Alloy.

The improvement and mechanism of the fatigue resistance of TC21 high-strength titanium alloy with a high velocity oxygen fuel (HVOF) sprayed WC-17Co coating was investigated. X-ray diffraction (XRD) and the corresponding stress measurement instrument, a surface roughness tester, a micro-hardness tester, and a scanning electron microscope (SEM) were used to determine the properties of the HVOF WC-17Co coating with or without shot peening. The fatigue behavior of the TC21 titanium alloy with or without the WC-17Co coating was determined by using a rotating bending fatigue testing machine. The results revealed that the polished HVOF sprayed WC-17Co coating had almost the same fatigue resistance as the TC21 titanium alloy substrate. This resulted from the polishing-induced residual surface compressive stress and a decrease in the stress concentration on the surface of the coating. Moderate-intensity shot peening of the polished WC-17Co coatings resulted in significant improvement of the fatigue resistance of the alloy. Furthermore, the fatigue life was substantially higher than that of the substrate, owing to the deep distribution of residual stress and high compressive stress induced by shot peening. The improved surface toughness of the coating can effectively delay the initiation of fatigue crack propagation.

Comparative study on small fatigue crack propagation between Fe-30Mn-3Si-3Al and Fe-23Mn-0.5C twinning-induced plasticity steels: Aspects of non-propagation of small fatigue cracks

We investigated small fatigue crack propagation in Fe-30Mn-3Si-3Al and Fe-23Mn-0.5C twinning-induced plasticity steels at 30Hz at ambient temperature by using the replica method with a rotating bending fatigue test machine. The most important difference between the two steels was observed in the non-propagation behavior of small fatigue cracks at the fatigue limits. The Fe-30Mn-3Si-3Al steel did not show fatigue crack non-propagation even at 108 cycles, whereas the Fe-23Mn-0.5C did after 107 cycles, likely because of the occurrence of dynamic strain aging associated with Mn-C coupling.

Evaluation of fatigue properties of EN31 steel heat treated using biodegradable gingili oil

Rotating bending fatigue is the most commonly encountered loading in most machines and machine tools. At the same time, modern literature in this area is very little. EN31 steel is a steel which is commonly used in load bearing applications which encounters fatigue loading. Further, studies on heat treated EN31 steel to improve fatigue strength is hardly reported. This paper takes this rare issue further ahead by using bio-degradable gingili oil to heat treat EN31 steel for fatigue applications. This paper reports the results of rotating bending fatigue study of EN31 steel. Fatigue tests were conducted for three conditions a) Untreated, b) Heat treated with water, and c) Heat treated with gingili oil, with cantilever loads ranging from 30% to 90% using double sided rotating bending fatigue testing machine. It is seen that EN31 steel heat treated using gingili oil has far superior fatigue properties than water treated and untreated ones, with gingili oil quenched specimen have ∼10 times more fatigue life than water quenched specimen and ∼100 times more than unquenched specimens when lower bending stresses are involved.

Effect of shot peening using ultra-fine particles on fatigue properties of 5056 aluminum alloy under rotating bending

Shot peening using particles 10μm in diameter (ultra-fine particle peening: Ultra-FPP) was introduced to improve the fatigue properties of 5056 aluminum alloy. The surface microstructures of the Ultra-FPP treated specimens were characterized using a micro-Vickers hardness tester, scanning electron microscopy (SEM), X-ray diffraction (XRD), non-contact scanning white light interferometry, and electron backscatter diffraction (EBSD). The Ultra-FPP treated specimen had higher hardness than the conventional FPP treated specimen with a short nozzle distance due to the high velocity of the ultra-fine particles. Furthermore, the surface hardness of the Ultra-FPP treated specimen tended to increase as the peening time decreased. Fatigue tests were performed in air at room temperature using a cantilever-type rotating bending fatigue testing machine. It was found that the fatigue life of the Ultra-FPP treated specimen tended to increase with decreasing peening time. Mainly, the Ultra-FPP improved the fatigue properties of 5056 aluminum alloy in the very high cycle regime of more than 107 cycles compared with the un-peened specimens. This is because the release of the compressive residual stress is small during fatigue tests at low stress amplitudes.

Effect of Shot Peening Coverage on Fatigue Strengths of Steels and Aluminum Alloy

The relations between shot peening coverage and fatigue strength in the quenched-tempered and annealed medium-carbon steels and aluminum alloy A7075-T6 were experimentally studied using a rotating bending fatigue testing machine. It was found that the fatigue strengths of the annealed steel and aluminum alloy were increased by shot peening. On the other hand, the fatigue strength of the quenched-tempered steel were not increased by shot peening. Same shot peening condition causes the positive effect and the negative effect depending on the type of material. Moreover, the valuable coverage might depend on the type of material. More detailed work is necessary to resolve the issue.

Effect of Double Shot Peening on Room-Temperature Notched Fatigue Property of TC4 Titanium Alloy

Single shot peening (SSP) with cast-iron shot and double shot peening (DSP) with cast-iron shot and ceramic shot were applied to investigate the relationship between surface integrity status and the fatigue property of titanium alloy TC4 on the notched specimens (stress concentration coefficient Kt=1.7). Surface roughness, residual stress profile and fatigue curve of the notched specimens were tested using scanning profilometer, XRD residual stress tester and rotating-bending fatigue testing machine, respectively. The results showed that surface roughness decreased 18.3% from Ra 1.09 μm post SSP to Ra 0.89 μm after DSP. Moreover, the position of the maximum value of residual stress migrated out close to the surface and the value of surface residual stress raised 12.6% to-800MPa from SSP. Additionally, the fatigue limit of the notched specimens pose SSP increased 64.7% to 467MPa from 283 MPa of AM, furthermore, edged up by 8% from 432MPa on unpeened smooth samples. It may be concluded that the double shot peening on titanium alloy has, therefore, eliminated the weakness of fatigue property caused by stress concentration.

GS0201-411 リアルタイム疲労き裂観察によるSCM435の疲労き裂進展特性評価

In order to evaluate the fatigue strength of the machine structures, it is necessary to know the fatigue crack propagation properties. Conventionally, a replica method has been used to observe the fatigue crack propagation properties. However, a lot of time and trouble are taken with copying the fatigue crack shape down from the specimen surface. Thus, real-time fatigue crack observation system for a rotating bending fatigue testing machine has been newly developed in this study. The purpose of this study is to investigate the fatigue crack propagation properties of JIS SCM435 under very high cycle regime by using the newly developed system.

THE USE OF A NEODYMIUM FATIGUE TESTING MACHINE FOR FATIGUE STRENGTH EVALUATIONS

This article proposes a method and a laboratory setup for testing the fatigue strength of materials with the use of vibration signals and a neodymium fatigue-testing machine. The machine supports non-contact fatigue testing of construction materials, and analyses of bending and torsional behaviour of magnetic and non-magnetic materials at any excitation range. The discussed machine is a non-contact bending device, and when an appropriate adapter is used, it supports analyses of torsional behaviour in determinations of material wear. A neodymium fatigue-testing machine can also be used to evaluate sample deformation by registering amplitude, RMS deviation from equilibriumcalculated values, temperature of sample notch, deflections along the length of the sample, stress at the cross-section of the notch and load applied at the terminal section of the sample. Simplified diagram of a rotating-bending fatigue testing machine, diagrams of biaxial rotating-bending fatigue testing machines, diagrams of a bending fatigue testing machine, displacement range of a material point in the sample induced by neodymium magnets on a double disc, displacement range of a material point in the sample at rotational frequency, displacement range of a material point in the sample at rotational frequency, changes in the sample's notch temperature and displacement amplitude are presented in the paper.

Fatigue behaviour of Al–25Zn–3Cu alloy

In the present study, Al–25Zn–3Cu alloy was prepared by permanent mould casting. Fatigue behaviour of the alloy was investigated using a rotating bending fatigue test machine after determining its microstructural features and mechanical properties. It was observed that as-cast microstructure of the Al–25Zn–3Cu alloy consisted of aluminium rich α dendrites, eutectoid α+η phases and θ particles. Homogenisation and T6 heat treatment removed the dendritic microstructure of the alloy and produced a large grained microstructure together with zinc rich precipitates. Both heat treatments increased the hardness and strengths of the alloy, but reduced its ductility. The Al–25Zn–3Cu alloy exhibited the lowest and the highest fatigue strengths in the as-cast and T6 heat treated conditions respectively. The fatigue strength of the Al–25Zn–3Cu alloy was found to be much greater than that of the Al–12Si alloy. It was observed that the fatigue behaviour of Al–25Zn–3Cu alloy can be expressed by the Basquin equation.

1109 極限環境下におけるギガサイクル4連式回転曲げ疲労試験機の開発(GS-3 接触)

In order to investigate the fatigue characteristics of metallic materials experimentally, a long period of time is required to get sufficient number of S-N data. In recent years, in order to overcome this difficulty, multi-type rotating bending fatigue testing machine whose name is GIGA QUAD have been developed by Yamamoto Metal Technos Co., Ltd., in which four specimens can be tested simultaneously. In this time, some additional new functions have been developed as follows; (1) 'high and low temperature environmental testing unit' whose target temperature is in a range of 600°C and -150deg.C, (2) 'constant temperature/humid environmental testing unit' combined with the conventional corrosive cell, (3) ‘fracture alarm unit’, and (4) ‘2-step variable loading unit’. By combining these new functions with the machine of GIGA QUAD, one can perform the fatigue tests efficiently corresponding to the respective requirements for researchers in both of academic and industrial sectors.