1,721,192 research outputs found
Modified Wöhler Curve Method, Theory of Critical Distances and EUROCODE 3: a novel engineering procedure to predict the lifetime of steel welded joints subjected to both uniaxial and multiaxial fatigue loading
No full textIn order to propose a procedure suitable for assessing steel welded joints by post-processing simple linear-elastic finite element (FE) models, this paper summarises an attempt to formalise a novel approach based on the use of the modified Wöhler curve method (MWCM) applied along with the theory of critical distances (TCD). This engineering procedure was initially calibrated by using the standard curves supplied by Eurocode 3. Subsequently, an unifying value for the multiaxial critical distance was calculated by taking full advantage from the notch-stress intensity factor (N-SIF) approach. The accuracy and reliability of the devised method was systematically checked by using a large amount of data taken from the literature and generated by testing steel welded details both under uniaxial and multiaxial nominal loading. In particular, both standard cruciform joints and structural details having complex geometries were considered and the devised procedure was applied to specimens tested both in as-welded and in stress-relieved condition. This approach was seen to be highly accurate, giving estimates falling within the widest standard scatter band between the two used to calibrate the approach itself. In particular, our method proved to be capable of correctly taking into account the scale effect as well as the degree of non-proportionality of the stress field damaging the fatigue process zone. Such results are very interesting and promising, especially in light of the fact that the numerical effort which has to be made to apply the proposed approach is the same as the one needed to apply other existing linear-elastic approaches
Multiaxial fatigue behaviour of composite laminates
No full textThe behaviour of composite laminates and tubes subjected to multiaxial fatigue loads is analysed and discussed. Experimental data taken from literature are compared to investigate the influence of the main design parameters on the multiaxial fatigue strength. The effects of biaxiality ratio, off-axis angle, phase angle between load components as well as the presence of notches have been considered. The biaxiality ratio turned out to be the more influencing design parameter, for both smooth and notched component
Biaxial Non-Proportional Variable Amplitude Testing and Analysis on Bicycle Welded Components for the Definition of a Safety Standard
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Multiaxial fatigue behaviour of composite laminates
No full textThe behaviour of composite laminates and tubes subjected to multiaxial fatigue loads is analysed and discussed. Experimental data taken from literature are compared to investigate the influence of the main design parameters on the multiaxial fatigue strength. The effects of biaxiality ratio, off-axis angle, phase angle 5 between load components as well as the presence of notches have been considered. The biaxiality ratio turned out to be the more influencing design parameter, for both smooth and notched component
Fatigue Life Prediction for 6082-T6 Cylindrical Specimens Subjected to In-phase and Out-of-phase Bending/Torsion Loadings
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High-cycle fatigue crack paths in specimens having different stress concentration features
No full textMultiaxial fatigue life predictions by using modified manson-coffin curves
No full textIn the present study, a novel multiaxial strain based approach is proposed and validated using a number of data sets taken from the literature. The plane experiencing the maximum shear strain amplitude (critical plane) is assumed here to be coincident with the micro-crack initiation plane. The proposed technique requires the calculation both of the shear strain amplitude and of the maximum normal strain relative to the critical plane. Multiaxial fatigue life predictions are made by means of bi-parametric modified Manson-Coffin curves, which take into account the mean stress effect as well as the influence of non-zero out-of-phase angles
Fatigue behaviour and life assessment of composite laminates under multiaxial loadings
No full textA thorough analysis of fatigue of composite laminates under multiaxial loading is presented. A large body of experimental data taken from the literature is examined to delineate the influence on the fatigue strength of factors such as biaxiality ratios and off-axis and out-of-phase angles. The data are found to clearly suggest that the ply-level shear biaxiality ratio, defined as the ratio of the shear stress amplitude to the largest normal stress amplitude, is the governing factor. The multiaxial fatigue criteria are examined next. The empirical method proposed by Ellyin and co-workers, based on the assumed log-linear fatigue life relationship, is compared with data. The Tsai-Hill and Smith-Pascoe quadratic polynomial criteria are also scrutinised. Finally, a mechanisms-based approach to multiaxial fatigue is outlined and proposed as the way to developing a reliable life prediction methodology
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