Effects of mean shear stress on the torsional fatigue strength of a spring steel with small scratches

2019 ◽  
Vol 29 (1) ◽  
pp. 4-18 ◽  
Author(s):  
Y Nishimura ◽  
K Yanase ◽  
Y Tanaka ◽  
N Miyamoto ◽  
S Miyakawa ◽  
...  
Keyword(s):  
Shear Stress ◽  
Fatigue Limit ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
High Strength ◽  
Spring Steel ◽  
Material Condition ◽  
Torsional Fatigue ◽  
Static Shear

The torsional fatigue behavior of a high-strength spring steel, SWOSC-V, was investigated. Of particular interest were the influences of small scratches and superimposed static shear stress in the very high cycle fatigue regime. To achieve the research objectives, an ultrasonic torsional fatigue testing machine was developed. S-Ncurves showed the fatigue limit for the tested material condition (i.e. with no residual stresses at specimen surface). This study revealed that a notable influence of the stress ratio, R, on the torsional fatigue behavior was not explicitly recognized. Concerning the influence of small scratches, it was found that the [Formula: see text]-parameter model can predict the lower bound of the torsional fatigue limit, irrespective of the value of R.

Fretting Fatigue Testing of Carburized Alloy Steel in Very High Cycle Regime Using an Ultrasonic Torsional Fatigue Testing Machine

2014 ◽  
Vol 891-892 ◽  
pp. 1152-1156
Author(s):  
Yoshinobu Shimamura ◽  
Akito Kokubo ◽  
Hitoshi Ishii ◽  
Keiichiro Tohgo ◽  
Tomoyuki Fujii ◽  
...  
Keyword(s):  
Fatigue Testing ◽  
Testing Machine ◽  
Fatigue Property ◽  
High Strength ◽  
Fretting Fatigue ◽  
Testing Method ◽  
Torsional Fatigue ◽  
Alloy Steels ◽  
Strength Alloy ◽  
Very High

Recently, high-strength alloy steels have been developed and used for various products. It is well known that fretting fatigue does not show fatigue limit. In other words, fretting fatigue failure may occur in very high cycle regime more than 107 cycles. However, it is difficult to investigate fretting fatigue property in very high cycle regime by using conventional fatigue testing machines because it is time-consuming. In this study, a fretting fatigue testing method for carburized alloy steels in very high cycle regime is explored by using an ultrasonic torsional fatigue testing machine. Carburized SCM420H was used for investigation. The experimental results showed that it is possible to conduct fretting fatigue testing of carburized alloy steels by using an ultrasonic torsional fatigue testing machine.

Very Long Life Fatigue Behavior of Bearing Steel AISI 52100

2005 ◽  
Vol 297-300 ◽  
pp. 1846-1851 ◽  
Author(s):  
Q.Y. Wang ◽  
Hong Yan Zhang ◽  
M.R. Sriraman ◽  
Shou Xin Li
Keyword(s):  
Fatigue Limit ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Bearing Steel ◽  
Aisi 52100 ◽  
Steel Aisi ◽  
Reversed Loading ◽  
Long Life ◽  
Number Of Cycles

For many applications, the understanding of very long life fatigue in materials becomes extremely important. In this study, the fatigue behavior of bearing steel GCr15 (conforming to AISI 52100) at very high number of cycles has been examined. Experiments on hourglass specimens were conducted in air at room temperature, for fully reversed loading condition (R=-1), using a piezoelectric fatigue testing machine operating at a frequency of 20kHz. The results indicate that the S-N data does not reach a horizontal asymptote (signifying the fatigue limit) at 107 cycles, as conventionally believed, and that the material can fracture up to 109 cycles. Therefore, to quote a fatigue limit at 107 cycles may not hold good for the material studied. The influence of defects (such as inclusions) on the crack initiation and fracture was analyzed by scanning electron microscopy.

Gigacycle Fatigue of Welded Joints of Structural Materials (A Review)

2016 ◽  
Vol 17 ◽  
pp. 14-30 ◽  
Author(s):  
Okechukwu P. Nwachukwu ◽  
Alexander V. Gridasov ◽  
Ekaterina A. Gridasova
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Structural Materials ◽  
Fatigue Tests ◽  
Material Defects ◽  
Graphite Cast Iron ◽  
Ultrasonic Fatigue ◽  
Materials Used ◽  
Fatigue Failures

This review looks into the state of gigacycle fatigue behavior of some structural materials used in engineering works. Particular attention is given to the use of ultrasonic fatigue testing machine (USF-2000) due to its important role in conducting gigacycle fatigue tests. Gigacycle fatigue behavior of most materials used for very long life engineering applications is reviewed.Gigacycle fatigue behavior of magnesium alloys, aluminum alloys, titanium alloys, spheroid graphite cast iron, steels and nickel alloys are reviewed together with the examination of the most common material defects that initiate gigacycle fatigue failures in these materials. In addition, the stage-by-stage fatigue crack developments in the gigacycle regime are reviewed. This review is concluded by suggesting the directions for future works in gigacycle fatigue.

Improvement of Fatigue Behaviour of High Strength Aluminium Alloys by Fluidized Bed Peening (FBP)

2007 ◽  
Vol 344 ◽  
pp. 87-96 ◽  
Author(s):  
M. Barletta ◽  
F. Lambiase ◽  
Vincenzo Tagliaferri
Keyword(s):  
Fatigue Life ◽  
Fluidized Bed ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Maximum Amplitude ◽  
High Strength ◽  
Operational Parameters ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

This paper deals with a definition of a relatively novel technique to improve the fatigue behavior of high strength aluminum alloys, namely, Fluidized Bed Peening (FBP). Fatigue samples made from AA 6082 T6 alloy were chosen according to ASTM regulation about rotating bending fatigue test and, subsequently, treated by varying FBP operational parameters and fatigue testing conditions. First, a full factorial experimental plan was performed to assess the trend of number of cycles to rupture of fatigue samples varying among several experimental levels the factors peening time and maximum amplitude of alternating stress applied to fatigue samples during rotating bending fatigue tests. Second, design of experiment (DOE) technique was used to analyze the influence of FBP operational parameters on fatigue life of AA 6082 T6 alloy. Finally, ruptures of FB treated samples and untreated samples were discussed in order to evaluate the influence of operational parameters on the effectiveness of FBP process and to understand the leading process mechanisms. At any rate, the fatigue behavior of processed components was found to be significantly improved, thereby proving the suitability of FBP process as alternative mechanical technique to enhance fatigue life of components made from high strength aluminum alloy.

Gigacycle Fatigue Behavior of 1800 MPa Grade High Strength Spring Steel for Automobile Lightweight

2014 ◽  
Vol 21 (6) ◽  
pp. 614-618 ◽  
Author(s):  
Ji-ming Zhang ◽  
Ling-kang Ji ◽  
Dong-jie Bao ◽  
Yao-rong Feng ◽  
Shou-xin Li ◽  
...  
Keyword(s):  
Fatigue Behavior ◽  
High Strength ◽  
Spring Steel

A Study on Fatigue Behavior of SM490A Steel under Low Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 142-145 ◽  
Author(s):  
Ki Weon Kang ◽  
Byeong Choon Goo ◽  
J.H. Kim ◽  
Heung Seob Kim ◽  
Jung Kyu Kim
Keyword(s):  
Fatigue Life ◽  
Low Temperature ◽  
Test Temperature ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Static Strength ◽  
Experimental Results ◽  
Railway Vehicle

This paper deals with the fatigue behavior and its statistical properties of SM490A steel at various temperatures, which is utilized in the railway vehicle. For these goals, the tensile ad fatigue tests were performed by using a servo-hydraulic fatigue testing machine at three temperatures: +20°C, -10°C and -40°C. The static strength and fatigue limits of SM490A steel were increased with decreasing of test temperature. The probabilistic properties of fatigue behavior are investigated by means of probabilistic stress-life (P-S-N) curve and they are well in conformance with the experimental results regardless of temperature. Also, based on P-S-N curves, the variation of fatigue life is investigated and as the temperature decreases, the variation of fatigue life increases moderately.

Fatigue Assessment of Tubular Automotive Components in Presence of Inhomogeneities

2004 ◽  
Author(s):  
Stefano Beretta ◽  
Herna´n Juan Desimone ◽  
Andrea Poli
Keyword(s):  
Fatigue Limit ◽  
Detrimental Effect ◽  
Fatigue Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Probability Of Failure ◽  
Integral Approach ◽  
Material Strength ◽  
Automotive Components ◽  
Tubular Components

Tubular automotive components, e.g. stabilizers and half shafts, are components subjected to fatigue. In order to assess fatigue behavior of such components, it is important to know both the real load conditions as well as the material strength against multi-axial fatigue. For the second point, a detrimental effect in the fatigue limit of high strength steels is given by the defects present in the component, coming from the material (such as microinclusions, microvoids, etc) or for the process (e.g. handling marks). An integral approach in order to assess fatigue limit of tubular components is proposed. The attention is focused onto planar inhomogeneities, which are the most common in tubular products, though the methodology can be extended to different defect-shapes. The method is applied together with a probabilistic model, in order to analyze the probability of failure. In particular, two different processes (in terms of inhomogeneities present in the final component) are compared, and the results allow to evaluate, for example, the admissible load for the desired (or design) level of failure probability for the component.

Fatigue in Ti-6Al-4V at Very High Cycles

2007 ◽  
Vol 561-565 ◽  
pp. 259-262 ◽  
Author(s):  
X.J. Cao ◽  
M.R. Sriraman ◽  
Qing Yuan Wang
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Weight Ratio ◽  
High Strength ◽  
Ambient Air ◽  
Ti Alloys ◽  
Structural Applications ◽  
Ultrasonic Fatigue ◽  
Reversed Loading ◽  
Very High

The importance of determining and understanding the very high cycle fatigue behaviors of materials has gained strength in recent years. Ti-alloys, in view of their high strength-to-weight ratio, have a range of structural applications. Of these, Ti-6Al-4V, belonging to the alpha-beta type is the most widely used. The present paper deals with investigations on the fatigue behavior of TC4, the Chinese equivalent to Ti-6Al-4V, up to very high cycles. Fatigue testing was carried out on a piezoelectric ultrasonic fatigue machine operating at 20 kHz frequency. Hourglass shaped resonant specimens were tested in ambient air at room temperature under completely reversed loading conditions (R = -1). Failure in the alloy was seen to occur right up to the gigacycle regime, with the fractures being found to initiate from the surface unlike in steels. The fracture surfaces exhibit brittle characteristics containing river patterns and cleavage facets, as well as striations.

Determination of Fatigue Limit by Locati Methodusing S-N Curve Determined by Means of Thermographic Method

2014 ◽  
Vol 223 ◽  
pp. 362-373 ◽  
Author(s):  
Adam Lipski
Keyword(s):  
Fatigue Limit ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Fatigue Curve ◽  
Rotational Frequency ◽  
Automatic Equipment ◽  
Staircase Method ◽  
New Approach ◽  
Combined Application

Selected results of experimental research showing possibilities to combined accelerated methods, i.e. thermographic determination of the fatigue curve and estimating the fatigue limit, were presented in this paper. The tests were performed using the reversed bending fatigue-testing machine with a rotational frequency of 77 Hz. The main item of the test station was the thermographic camera. Test specimens were made of C45 (1.0503) steel drawn bars. The full tests results were presented for the fatigue S-N curve (23 specimens at 10 load levels) and fatigue limit by the Staircase method (25 specimens) based on 107 cycles to failure was determination. The accelerated test for determining the slope of the S-N curve and the fatigue limit were made by a single specimen based on gradually increasing loading. Methods previously presented in the literature are based on the phenomenon of temperature stabilization during most of the fatigue process. The results presented in this work did not show the occurrence of such a phenomenon. For that reason, the new approach to the determination of the slope of S-N curve was proposed. Combined application of both experimental methods, Locati and thermographic, with a new approach to the determination of this slope might allow one to develop automatic equipment for the accelerated determination of the fatigue limit which would contribute to significant reduction of the test costs and time, thus increasing availability of such tests.

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