•A Gaussian process-based fatigue life prediction model is proposed.•The shear and normal stress components on the critical plane are the input data.•The fatigue data of S355N steel and 2124 T851 ...alloy are analyzed.•The square exponential kernel predicts the fatigue lives of datasets accurately.•Square mapped input data results in the best life prediction for both datasets.
Fatigue life prediction with failure probability estimation for materials subjected to multiaxial loading is an important task in engineering design because it reduces the financial cost by eliminating expensive experimental tests. Owing to the complex deterioration mechanisms of fatigue failure, existing fatigue life prediction models are of the empirical or semi-empirical type, and their applicability is limited to validating the loading condition and material. Improper selection of the fatigue model could result in non-conservative life prediction with high financial and catastrophic consequences. To solve this problem, an innovative approach based on the Gaussian process for fatigue life prediction under multiaxial loading is presented. The inherent features of the Gaussian process predispose its application to fatigue life prediction under multiaxial loading as an efficient and practical approach to avoid the problem in selecting adequate semi-empirical parametric fatigue models. The model was validated on two sets of experimental data obtained by fatigue testing of S355N steel and 2124 T851 aluminum alloy under uniaxial and multiaxial loadings. In the model training process, only data obtained under uniaxial and pure torsion cyclic loadings were applied. Owing to the implemented physics-based input data, which are related to the stress components acting on the critical plane of crack initiation, the model accurately predicted the fatigue lives of the two tested materials by implementing the squared exponential covariance function. In addition, the fatigue lives were also computed using four parametric fatigue strength criteria (Crossland, Matake, Carpinteri et al., and Papuga–Růžička models). The best results obtained by the parametric models exhibited a lower fatigue prediction performance than the results using the Gaussian process-based model.
•Fine shot peening has superior effects on fatigue performance.•FLPF is prolonged more than 25 times.•FSIP is more than 76%.•Fatigue cracks locate beneath the surface enhanced layer induced by shot ...peening.
The effect of shot peening on Ti2AlNb fatigue performance was investigated. Glass fine shot peening was used and residual stresses were measured by XRD technology and electropolishing method. Rotating bending fatigue test was performed. The results show compressive residual stress is introduced and the maximum is 322 MPa, and fatigue property is significantly improved. The high cycle fatigue life is prolonged more than 25 times and fatigue endurance limit is increased from 170 MPa to 360 MPa. Moreover, fatigue cracks initiate beneath surface enhanced layer for SP specimens, while for referenced specimens they are located at surface.
High cycle and very high cycle fatigue (HCF/VHCF) in a bainite/martensite (B/M) multiphase steel with varying inclusion size and microstructural features was studied using ultrasonic axial cycling ...test. The fatigue crack initiation was predominantly induced by inclusions in specimens with large inclusion size, whereas fatigue crack initiated from the sub-surface microstructure in specimens with coarse microstructure. The fatigue life from granular bright facet (GBF) to fish-eye and from fish-eye to the critical crack size was calculated to obtain an estimate of the contribution to fatigue life by GBF, for the two modes of crack initiation within the HCF/VHCF regime. The results demonstrated that the majority of fatigue life was consumed by the crack initiation process along with the formation of GBF irrespective of whether the crack initiated from inclusions or from sub-surface microstructure. In the case of crack initiation from sub-surface microstructure, the ratio of fatigue crack initiation life to total fatigue life (Ni/Nf) had a wide scatter, which is attributed to varying B/M hierarchical structure in individual prior austenite grains.
•Multiaxial models can be successfully adapted to estimate fretting fatigue life.•New data for Ti-6Al-4V cylinder/plane contact to evaluate wear-based life analysis.•Critical distance/plane method ...yields accurate estimates of fretting fatigue life.•Inclusion of wear in the modeling did not significantly improved the life estimates.•Elastic-plastic analysis of AA6201-T81 contacting wires improves life estimates.
The aim of this work is to show that multiaxial fatigue modeling can be successfully adapted to estimate crack initiation life of mechanical assemblies under fretting conditions. The paper is divided into two parts. In Part I, the focus is on the study of size and gradient effects but considering the influence of incorporating fretting wear on the life estimation procedure. New data for a Ti-6Al-4V cylindrical on plane contact configuration were produced to assess the analyses. It is shown that critical plane criteria, coupled with a critical distance which varies with life, are capable to provide accurate estimates of fretting fatigue life in the medium high cycle regime. The inclusion of wear in the modeling did not significantly improved the life estimates but increased a lot the computational cost. In Part II, the paper extended this life estimation approach to the contact of wires taken from overhead conductors. Fretting fatigue data of AA1350-H19 wires and new tests on the more resistant AA6201-T81 corroborated the successful use of the life methodology to other materials and applications.
This updated textbook is for people working on fatigue problems of engineering structures and materials associated with design, predictions, load spectra and experimental verifications.
•An iron-based shape memory alloy is exploited for fatigue mitigation.•The proposed solution combines the merits of bridging and prestressing mechanisms.•The bonded smart patch is highly effective in ...retarding fatigue crack growth.
An innovative fatigue strengthening solution for metallic structures that takes advantage of the shape memory effect of an iron-based shape memory alloy (Fe-SMA) and the bridging mechanism offered by the bonding technique has been proposed and examined. Fatigue tests on cracked steel plates with bonded carbon fiber-reinforced polymer (CFRP) and nonprestressed and prestressed Fe-SMA strips were conducted. The experimental results demonstrate that the bonded prestressed Fe-SMA strips are much more effective than CFRP strips, extending the fatigue crack growth life by a factor of 3.51. The proposed innovative solution is highly effective in retarding fatigue crack growth in metallic structures.
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•Solid solution strengthening is a prime contributor for resisting surface and subsurface initiated damage.•RCF caused strain hardening may not be a significant contributor to extend ...the fatigue life.•Owing its chemical composition and microstructural characteristics, the 3310 steel showed better fatigue performance than 52100.
In this study, different microstructures were generated in steels by varying the heat treat parameters and were tested under rolling contact fatigue (RCF) and under specific test conditions known to cause white etching cracks (WECs). Case carburized AISI 3310 steel showed significantly longer fatigue life than martensitically through-hardened 52100 steel. In addition, this study examined carburized steel that had been heat treated differently and RCF tested. The 3310 steel was carburized at a lower carbon potential and subsequently, the carburized steel was austenitized at a lower temperature so that lesser solute quantities had dissolved into the austenite phase prior to the quench step. The carburized steel samples with less solute dissolution showed higher hardness and more compressive stresses than the original carburized steel; however, they showed 75% shorter RCF life than the original carburized steel. These results suggest that solid solution strengthening is a significant contributor to fatigue resistance under WEC damage conditions.
•The model is expanded to include equations for estimating the model parameters in terms of common properties of metals.•The model is able to simulate the hysteresis behavior of materials.•The ...Constant Fatigue Life Diagram for A36 is presented.•Dramatic increase in energy loss before dropping to zero and failure due to fatigue is observed.
This paper presents further development of a spring mechanical system, proposed by Guranlick et al, in (1) deriving equations for the determination of the mechanical system parameters in terms of material properties; (2) developing applications for deriving fatigue life relations with consideration for the ratio of the minimum to maximum stress; and (3) extending the model to incorporate the hysteresis behavior of steel under cycling loading. These applications are demonstrated in this paper with numerical illustrations.
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