共查询到20条相似文献,搜索用时 15 毫秒
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N. I. I. Mansor S. Abdullah A. K. Ariffin 《Journal of Mechanical Science and Technology》2017,31(10):4719-4726
This paper discusses the fatigue life behaviour of the API X65 steel tested under constant amplitude loading in ambient temperature. The influence of repeated loading at a particular stress ratio would favour the initiation of fatigue cracks that would consequently affect the fatigue crack growth. The main objective of this paper is to evaluate the load ratio effects on fatigue crack growth rate, taking into account their statistical characteristics. The fatigue crack growth test was carried out using compact-tension specimen at different load ratios of 0.1, 0.4 and 0.7. The experimental results showed the crack growth rate was dependent on the applied load. It was observed that the load ratio effect was less significant in stable crack growth regions. The result was consistent with the multiple regression test obtained by the least square method at a significance level of 0.05. The empirical model of Paris and Walker was utilised to evaluate the effects of load ratio on the fatigue crack growth rates. The approximation of fatigue life lies between 10-25 % of error using conservative model and 6 % error using the Walker model. The experimental data was scattered within a factor-of-2 correlation line suggesting that the accuracy of the experimental data towards the estimated values was high. 相似文献
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Bumjoon Kim Jonghoon Lee Jiwoo Im Jongbum Kim Moonki Kim Hakjoon Kim Sungjin Song Byeongsoo Lim 《Journal of Mechanical Science and Technology》2012,26(10):3091-3096
In this work, we examined the influence of microstructural changes, such as an intermetallic sigma (??) phase, on the fatigue behavior of high-temperature aged AISI 316L stainless steel. Nondestructive ultrasonic test and fatigue crack growth tests were performed to determine the threshold stress intensity factor of these artificially aged specimens. Ultrasonic test results characterizing the microstructural changes were compared with those of the fatigue tests to propose an empirical formula capable of predicting the threshold stress intensity factor by a nondestructive method. We observed a strong correlation between the increase in the volume fraction of the ?? phase and the decrease of ??Kth. Ultrasonic velocity increased in response to the coarsening behavior of the ?? phase in the vicinity of the grain boundaries. 相似文献
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Y.W. Mai 《International Journal of Mechanical Sciences》1978,20(5):293-298
An account of the quasistatic fatigue crack growth under cyclic loading and cyclic displacement is given in terms of the load-deflection (X − u) and fracture resistance-crack area (R − A) diagrams. Experimental results are reported in support of the concepts proposed. 相似文献
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G. V. Moskvitin S. G. Lebedinskii 《Journal of Machinery Manufacture and Reliability》2013,42(5):439-444
Experiment-calculated modeling of fatigue crack development of 20 GFL cast steel in railroad constructions irregularly loaded has been carried out. The loading of samples involves tensile overloads from the operational range of loading of freight car bogies. The calculation implies a complete fatigue failure diagram of the steel under study and a concept of the effective stress intensity factor at the overload-affected site. The parameters used in the calculation are determined from the results of tests. The calculation is correlated with the results of the experiment. 相似文献
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Yan Huan Wei Peitang Zhou Pengliang Chen Ling Liu Huaiju Zhu Caichao 《Journal of Mechanical Science and Technology》2022,36(3):1233-1242
Journal of Mechanical Science and Technology - Tooth bending fatigue remains as a fundamental bottleneck restricting the safety and reliability of modern high-performance gear. In this study, a... 相似文献
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The results of a numerical investigation on fatigue crack growth of an offshore tubular T-joint under the action of axial, in-plane and out-of-plane bending loads are presented in this paper. Extensive stress analysis has been carried out to determine the location of the hot spot stress along the brace—chord intersection for each load case. Semi-elliptical cracks with varying crack lengths and crack depths were introduced at the hot spot location by means of line spring elements for stress intensity factor evaluation. The line springs were properly constrained to prevent the problem of crack surface penetration. The stress intensity factors obtained are then used in a crack growth law for life estimation. 相似文献
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G. V. Moskvitin S. G. Lebedinskii 《Journal of Machinery Manufacture and Reliability》2016,45(5):429-432
The paper presents the results of an experimental study on the features of fatigue crack development in 20GFL grade low-alloy steel of a freight car bolster with simulation of the operating process of loading. The experiment results are compared with calculations using the fatigue failure diagram for this steel. 相似文献
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A probabilistic analysis on variability of fatigue crack growth using the markov chain 总被引:1,自引:0,他引:1
Understanding the stochastic properties of variability in fatigue crack growth is important to maintaining the reliability
and safety of structures. In this study, a stochastic model is proposed to describe crack growth behavior considering the
variability of fatigue crack growth rates due to the heterogeneity of material. Fatigue life distribution is then predicted
based on this model To construct this model, fatigue tests are conducted on a high strength aluminum alloy 7075 T6 under constant
stress intensity factor range control. The variability of fatigue crack growth rates is expressed by random variablesZ and Γ based on the variability of material constantsC andm of the Paris-Erdogan equation. The distribution of fatigue life under constant stress intensity factor ranges is evaluated
by the stochastic Markov chain model based on the Paris-Erdogan equation. The merit of the proposed model is that only a small
number of tests are required to determine this function, and fatigue life required to reach certain crack length at a given
stress intensity factor range can be easily predicted.
Department of Mechanical Design and Production Eng. 相似文献
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A new crack propagation effect is discussed analytically and demonstrated experimentally. It is shown that local one-dimensional variations in yield strength (strength gradients) can effect a major change in the rate of crack growth under conditions of constant amplitude cycled stress intensity at the crack tip as determined by linear elastic fracture mechanics. Rice's path independent integral is combined with certain fracture mechanics arguments to derive a crack propagation law which predicts that crack extension per cycle is modulated by strength gradients if they are present, in proportion to their slope. Experimental data are developed for two aluminum alloys which demonstrate the effect conclusively. The importance of these results as they apply to real engineering components where strength gradients are known to occur because of casting, forging, rolling, joining, etc. is discussed. The strength gradient effect is shown to be discrete and separate from other effects including the influence of local levels of strength. 相似文献
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《Measurement》2014
In this paper, two silicon nitride layers with thickness, 0.2 and 0.4 μm, are coated onto single crystal silicon (SCS) in order to achieve Si3N4/Si cantilever microbeams. The effect of LPCVD silicon nitride surface coatings on fatigue properties of SCS cantilever microbeams is investigated. Fatigue testing is conducted at both 40 Hz and 100 Hz. Typical S–N (strain amplitude–fatigue cycle) curves of the beams are achieved and correlated fatigue failure modes are investigated. It is found that thinner Si3N4 coating of 0.2 μm results in better fatigue lives of Si3N4/Si beams than thicker Si3N4 coating of 0.4 μm. Both thinner and thicker coated beams have major fatigue crack planes along {1 1 1} planes; however, thicker coated beams possess specific failure mode of delamination, which is not found in thinner coated beams. Delamination reduces the reinforcing effect of thicker Si3N4 coating and leads to its shorter fatigue life. For thicker coated beams, fatigue life at 100 Hz is longer than that at 40 Hz. The mechanism for delamination and the effect of cyclic frequency is investigated, and factors for better fatigue life are proposed. 相似文献
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This paper concerns the modelling of the rolling contact fatigue of a railway wheel steel, which is simulated with moving Hertzian contact pressure. Parametric studies are carried out with a two-dimensional elastic-plastic finite element model of a part of a wheel containing defects. Several parameters, namely the size and shape of material defects, the load magnitude and the friction coefficient are varied to investigate their effect on the railway wheel fatigue damage. Defects or small friction coefficient are a plausible explanation to the initiation of deep subsurface fatigue cracks. 相似文献
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Ho-Kyung Kim Myung-Il Choi Chin-Sung Chung Dong-Hyuk Shin 《Journal of Mechanical Science and Technology》2002,16(10):1246-1252
Ultrafine grained (UFG) low carbon (0.15 wt.% C) steel produced by equal channel angular pressing (ECAP) was tested for investigating
the effect of load ratio on the fatigue crack growth rate. Fatigue crack growth resistance and threshold of UFG steel were
lower than that of as-received coarse grained steel. It was attributed to the less tortuous crack path. The UFG steel exhibited
slightly higher crack growth rates and a lower ΔKth with an increase of R ratio. The R ratio effect on crack growth rates and ΔKth was basically indistinguishable at lower load ratio (R>0.3), compared to other alloys, which indicates that contribution
of the crack closure vanishes. The crack growth rate curve for UFG steel exhibited a longer linear extension to the lower
growth rate regime than that for the coarse grained as-received steel. 相似文献
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Influence of coating thickness on rolling contact fatigue of alumina ceramics thermally sprayed on steel roller 总被引:4,自引:2,他引:2
Masahiro Fujii Jiabin Ma Akira Yoshida Sadato Shigemura Kazumi Tani 《Tribology International》2006,39(11):1447-1453
The influence of the sprayed layer thickness on rolling contact fatigue of a thermally sprayed alumina ceramics with a nominal composition of Al2O3–2.3 mass% TiO2 was investigated using a two-roller test machine under pure rolling contact condition with oil lubricant. The influence of undercoating of sprayed nickel-based alloy on rolling contact fatigue was also investigated. Thicknesses of the ceramics-sprayed layer of tested rollers were 0.2, 0.5 and 1.0 mm. The failure mode of sprayed rollers was spalling caused by subsurface cracking. In the case of sprayed rollers without undercoating, rolling contact fatigue strength of rollers with 0.2 mm thickness sprayed layer was the smallest. Rolling contact fatigue strength of sprayed roller with 0.2 mm thickness sprayed layer was improved by undercoating. In case the failure depth was small as compared with the thickness of sprayed layer, effect of undercoating on the rolling contact fatigue strength was little. The depths where the maximum values of subsurface shear stresses occurred, almost corresponded to the observed depth of spalling cracks. 相似文献
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Jorge Alberto Rodriguez DURAN Ronney Mancebo BOLOY Rafael Raider LEONI 《Frontiers of Mechanical Engineering》2015,10(3):255
The well-known fatigue crack growth (FCG) curves are two-parameter dependents. The range of the stress intensity factor ?K and the load ratio R are the parameters normally used for describing these curves. For engineering purposes, the mathematical representation of these curves should be integrated between the initial and final crack sizes in order to obtain the safety factors for stresses and life. First of all, it is necessary to reduce the dependence of the FCG curves to only one parameter. ?K is almost always selected and, in these conditions, considered as the crack driving force. Using experimental data from literature, the present paper shows how to perform multiple regression analyses using the traditional Walker approach and the more recent unified approach. The correlations so obtained are graphically analyzed in three dimensions. Numerical examples of crack growth analysis for cracks growing under nominal stresses of constant amplitude in smooth and notched geometries are performed, assuming an identical material component as that of the available experimental data. The resulting curves of crack size versus number of cycles (a vs. N) are then compared. The two models give approximately the same (a vs. N) curves in both geometries. Differences between the behaviors of the (a vs. N) curves in smooth and notched geometries are highlighted, and the reasons for these particular behaviors are discussed. 相似文献
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《Wear》1986,113(2):291-294
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Bolin He Haipeng Deng Mingming Jiang Kang Wei Li Li 《The International Journal of Advanced Manufacturing Technology》2018,95(5-8):1571-1595
This paper presents bi-criteria formulation of a tolerance allocation model for an interchangeable assembly to simultaneously evolve suitable combination of manufacturing facility in multiple facility shaft-hole production environments of medium- and large-scale industries and tolerances to complement the need of customers. An Exhaustive Search Procedure is used to obtain the optimal solution for small and medium size problems and simulated annealing algorithm is used for large size problems. The usefulness of the Pareto front in manufacturing tolerance allocation decisions is demonstrated with three case study problems. The effect of process capability of shaft-hole assembly manufactured from alternative manufacturing machines and the optimality is analyzed in three cases to understand their criticality in decision-making. The models discussed in this paper could be useful for medium- and large-scale manufacturing industries, where there will be a variety of manufacturing facilities (specifications, capabilities, models, and types) for making both shaft-hole assembly and play a key role to meet the tolerance and cost requirements of different customers. This paper further discusses how this formulation and methodologies can be used for two hole and two shaft assemblies and multiple shaft-hole assemblies. Finally, the paper ends with highlighting directions of future research avenues in the shaft-hole assembly. 相似文献