Determination of the Probabilistic Fatigue S-N Curves Including Super-Long Life Regime for a Railway Axle Steel

2008 ◽  
Vol 44-46 ◽  
pp. 57-64 ◽  
Author(s):  
Yong Xiang Zhao ◽  
Bing Yang ◽  
Ming Fei Feng
Keyword(s):  
High Frequency ◽  
Life Prediction ◽  
Test System ◽  
Test Results ◽  
Railway Axle ◽  
Basic Work ◽  
Specimen Test ◽  
Ultrasonic Fatigue ◽  
Long Life

The structures of railway vehicles are required to service in super-long life regime. Determination of the probabilistic S-N curves including the regime should be a basic work to realize the real fatigue life prediction and reliability assessment. Based on the test results of Chinese railway LZ50 axle carbon steel, a statistical extrapolating method is proposed to determine the curves by applying the conventional test data in mid-long life regime. Some phenomena, i.e. the response of “fatigue limit”, a great of heat affecting using the high frequency ultrasonic fatigue test system, and the non-conservative test results using the conventional frequency tiny multi-specimen test system (machine C), are firstly mentioned in the existent super-long life researches. The too much conservative offers are also noted by the determinations of existent codes. To address the variable amplitude loads in production, the present method extrapolates continuously the curves from the mid- to super-long life regimes under the statistical controls of conventional fatigue limits. The practice for the present material indicates that the curves can well reflect the scattered data not only in mid-long life regime but also in super-long life regime. The non-conservative test results using machine C are also safely included by the curves.

The Improved Friction Properties of Bonded MoS2 Films by MAO Treating of Al Substrate

2013 ◽  
Vol 275-277 ◽  
pp. 1911-1914 ◽  
Author(s):  
Han Jun Hu ◽  
Hui Zhou ◽  
Yu Gang Zheng ◽  
Kai Feng Zhang ◽  
Zhi Hua Wan
Keyword(s):  
Tribological Properties ◽  
Solid Lubricants ◽  
Ceramic Coatings ◽  
Test System ◽  
Test Method ◽  
Test Results ◽  
Specimen Test ◽  
Micro Arc Oxidation ◽  
A New Technique ◽  
Porous Microstructures

The bonded MoS2 films are widely used as solid lubricants in aerospace mechanisms due to their excellent tribological properties. Traditionally, the MoS2 was directly bonded on the Al substrate that was only treated by the technique named of sandblast. For improving the tribological properties of MoS2 films, micro arc oxidation (MAO) instead of sandblast was introduced as a new technique for treating of Al substrate. In this article, the tribological properties of MoS2 films which were bonded on different surface of Al substrate as mentioned above were discussed, respectively. It was concluded from the test results that the MoS2 films bonded on substrate treated by MAO have better tribological properties than those samples treated by sandblast. The endurance life against abrasion of the former is as high as twenty times of the latter by the stand test method of ball on disk using the UMT Multi-Specimen Test System. This test results could be illustrated by the following reasons. The first is the porous microstructures of MAO ceramic coatings on the Al substrate. The coatings have numerous pits to be good at increasing the binding force with the MoS2 films, and the pits can also provide a MoS2 lubricants reservoir during processes of friction. Both of them improved the MoS2 film’s ability of wear-protective. The second is that hardness of the coating is higher than the Al, and this ensures well wearing resistance, especially in practical application to big load-supporting moving parts, such as bearing, gear, etc…

Experiment Analysis about Mechanical Properties of Rubber Bushing for Suspension Telescopic Shock Absorber

2014 ◽  
Vol 670-671 ◽  
pp. 1008-1011 ◽  
Author(s):  
Li Ping Li
Keyword(s):  
High Frequency ◽  
Optimization Design ◽  
Shock Absorber ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Test System ◽  
Test Results ◽  
Static And Dynamic Characteristics ◽  
Rubber Bushing

The experiments of static and dynamic characteristics of rubber bushing for rear suspension telescopic shock absorber were carried out at four directions such as axial, radial, torsion and yaw, by MTS831 and SAGINOMIYA test system. The tests prove that: rubber bushing has great damping, and rubber bushing has obvious nonlinear characteristic; the dynamic stiffness under low frequency and large amplitude excitation is smaller, while the dynamic stiffness under high frequency and small amplitude excitation is greater; at the same amplitude, the dynamic stiffness increases with the increasing excitation frequency. The test results can provide support for the optimization design of rubber bushing.

Research on Ultra-High Cycle Fatigue Property of 45 Steel

2011 ◽  
Vol 295-297 ◽  
pp. 1911-1914
Author(s):  
Ling Ling Jin ◽  
Cai Yan Deng ◽  
Dong Po Wang ◽  
Rui Ying Tian
Keyword(s):  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Fatigue Property ◽  
Sem Analysis ◽  
Test Results ◽  
Cycle Fatigue ◽  
Welded Structure ◽  
Ultrasonic Fatigue ◽  
Long Life ◽  
Ultra High Cycle Fatigue

Fatigue property of 45 steel was studied in this paper with the method of ultrasonic fatigue testing, and SEM was used to analyze microscopic characteristics of the fatigue fracture. Fatigue test results show that: S-N curves descend continuously after 108 cycles, there is no fatigue limit as the traditional fatigue conception describes. Therefore, it is very dangerous to design welded structure working in the ultra-high cycle interval with the fatigue strength corresponding to 5×106 cycles. In the super-long life range, the fatigue property of welded joints is worse than the base metal. SEM analysis shows that: fatigue crack mainly initiates from the defects in the surface or sub-surface.

Ultrasonic Fatigue Performance of Welded Joints in 16Mn Steel

2012 ◽  
Vol 251 ◽  
pp. 392-396
Author(s):  
Liang Chen Wu ◽  
Dong Po Wang
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
Performance Test ◽  
Test System ◽  
Fatigue Performance ◽  
Traditional Concept ◽  
Welded Structure ◽  
Ultrasonic Fatigue ◽  
Long Life ◽  
16Mn Steel

Ultrasonic fatigue performance test of 16Mn steel and welded joints are carried out by using ultrasonic fatigue test system devices developed by Tianjin University to research its fatigue behavior in the super long life regime. The results show that: regardless of the base mental or welded joints, the S-N curve is a continuous decline curve; Welded joints does not exist the traditional concept of fatigue limit within the range of 106~107, when the number of load cycles exceeds 107 even 109, fatigue fracture still occurs. Within the super long life range, the fatigue strength of welded joint is much lower than the fatigue strength of base mental. It is dangerous to use the existing fatigue data to design the welded structure within the super long life regime.

An Axial-Torsional Extensometer for Finite Deformation

1990 ◽  
Vol 112 (3) ◽  
pp. 330-335 ◽  
Author(s):  
Han-Chin Wu ◽  
Zhiyou Xu
Keyword(s):  
Large Strain ◽  
Strain Range ◽  
Gage Section ◽  
Test Results ◽  
Torsional Loading ◽  
Tubular Specimen ◽  
Shear Deformations ◽  
Materials With Voids ◽  
Specimen Test

An axial-torsional extensometer has been designed, constructed and tested. This extensometer is suitable for use in the experimental determination of multiaxial plastic deformation and determination of fatigue fracture under moderately large strain range. The extensometer is applicable to tubular or solid cylindrical specimens, with enlarged ends, and measures the axial and shear deformations within a gage section of the specimen. It has been calibrated, and error bounds are given in terms of linearity, crosstalk, and hysteresis. The diametral strain can also be measured, which is especially useful in the testing of materials with voids. An application has been made to combined axial-torsional loading of a metal tubular specimen. Test results are presented.

Tensile Fatigue and Life Prediction of a SiC/SiC Composite

2001 ◽  
Author(s):  
Jun Shi
Keyword(s):  
Fatigue Life ◽  
High Frequency ◽  
Life Prediction ◽  
Low Frequency ◽  
Fatigue Life Prediction ◽  
Test Results ◽  
R Ratio ◽  
Tensile Fatigue ◽  
Stiffness Variation ◽  
Underlying Mechanisms

This paper summaries two sets of tension-tension fatigue results. The first set corresponds to low R ratio (0.1) and low frequency (1Hz), whereas the second set covers high R ratio (0.9) and high frequency (10Hz). For the former, detailed analysis of stress strain loops is conducted in connection with the underlying mechanisms that govern fatigue deformation and life. For the latter only stiffness variation with fatigue cycles is discussed. The test results are also examined for their impact on fatigue life prediction.

The Indentation Load-depth Curve of Ceramics

1999 ◽  
Vol 14 (4) ◽  
pp. 1471-1484 ◽  
Author(s):  
M. Sakai ◽  
S. Shimizu ◽  
T. Ishikawa
Keyword(s):  
Surface Deformation ◽  
Test System ◽  
Indentation Load ◽  
Quadratic Functions ◽  
Test Results ◽  
Extensive Test ◽  
Physical Insight ◽  
Loading And Unloading ◽  
Material Measure

The pyramidal indentation-induced surface deformation of brittle ceramics is examined on the basis of extensive test results for indentation load (P)-depth (h) curves during loading/unloading cycle. A mechanically stiff test system is essential for obtaining P-h curves acceptable and reliable for subsequent analyses. Both the loading and unloading P-h curves are expressed by quadratic functions within experimental variations for all the indenters used (Vickers, Berkovich, and Knoop). The loading curve is then related to the Meyer hardness and the unloading curve to Young's modulus by the use of semiempirical equations which enable one to estimate these moduli from the observed loading/unloading parameters. An elastoplastic constitutive equation for indentation surface deformation is theoretically derived. This equation not only predicts well the experimental observations but also gains an important physical insight into the Meyer hardness. The Meyer hardness of brittle materials is not a measure for plasticity, but an elastic/plastic parameter which significantly depends on the geometry of indenter. The concept and experimental determination of “true” hardness as a characteristic material measure for plasticity are proposed.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

Modified Earpieces and CROS for High Frequency Hearing Losses

1968 ◽  
Vol 11 (1) ◽  
pp. 204-218 ◽  
Author(s):  
Elizabeth Dodds ◽  
Earl Harford
Keyword(s):  
Hearing Loss ◽  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Sound Field ◽  
Intensity Level ◽  
Test Results ◽  
High Frequency Hearing Loss ◽  
Increased Sensitivity ◽  
Difficult Cases

Persons with a high frequency hearing loss are difficult cases for whom to find suitable amplification. We have experienced some success with this problem in our Hearing Clinics using a specially designed earmold with a hearing aid. Thirty-five cases with high frequency hearing losses were selected from our clinical files for analysis of test results using standard, vented, and open earpieces. A statistical analysis of test results revealed that PB scores in sound field, using an average conversational intensity level (70 dB SPL), were enhanced when utilizing any one of the three earmolds. This result was due undoubtedly to increased sensitivity provided by the hearing aid. Only the open earmold used with a CROS hearing aid resulted in a significant improvement in discrimination when compared with the group’s unaided PB score under earphones or when comparing inter-earmold scores. These findings suggest that the inclusion of the open earmold with a CROS aid in the audiologist’s armamentarium should increase his flexibility in selecting hearing aids for persons with a high frequency hearing loss.

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