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This study reports the variability of the fatigue strength of specimens manufactured by the laser powder bed fusion process with respect to their location on the build plate. Specimens from the right-hand and left-hand halves of the build plate were tested under high cycle fatigue. Comparison of the fatigue data suggests that the specimens manufactured on the right-hand half of the build plate have a higher fatigue strength than those manufactured on the left-hand half. One reason for the observed discrepancy in fatigue strength was the higher accumulation of spattered powder particles on the left-hand side as compared to the right-hand side of the build plate. These spattered particles are oxidised, and form defects such as inclusions within the specimen. © 2021 The Author(s)

The Birnbaum–Saunders distribution has been widely used to model reliability and fatigue data. In this paper, we propose a regression of generalized linear models type based on a new bivariate Birnbaum–Saunders distribution. This is parameterized in terms of its means and allows data to be described in their original scale. We estimate the model parameters and carry out inference with the maximum likelihood method. A case study with real-world reliability data is conducted for motivating our investigation, illustrating the potential applications of the proposed results. We obtain a predictive model which can be a useful addition to the tool-kit of diverse practitioners, reliability engineers, applied statisticians, and data scientists.

In this paper present the evaluation of Ultra-Thin White Topping using Fibre Reinforced Concrete as an overlaying concrete mix. In India, generally PCC and High Strength Concrete is used at various UTWTsites. In this paper, particular calculation for fatigue data for medium traffic road is carried out. In most of the UTWTpavement it is observed that the common failure type is cracking in pavement. The concrete is a brittle material and it early subjected to cracking. Polypropylene Fibre reinforced concrete is increase the flexural strength of pavement due to which the pavement failure due to cracking is reduced. This paper particularly highlights on Fatigue data by replacing the PCC with PPFRC (polypropylene fibre). These fibre concrete and their mix proportion are design according to IRC-44 guidelines for concrete mix design of rigid pavement. The M40 grade FRC is used for the calculation of fatigue data. Fatigue data is calculated as per IRC SP-76-2008 for medium traffic condition.

In the present investigation, a large number of fatigue data generated by testing welded joints of magnesium alloy AZ31 were post-processed based on the reference radius concept. The local stresses used to perform this systematic re-analysis were determined by setting the fictitious notch radius, r f , invariably equal to 0.3 mm. According to this strategy, local stress-based S-N curves were then derived for load ratios, R, equal to −1, 0 and to 0.5. This post-processing exercise allowed us to demonstrate that a fictitious notch radius of 0.3 mm is successful in modelling the fatigue strength of weldments made of magnesium alloy AZ31. In particular, with r f = 0.3 mm, this type of welded joints is recommended to be designed against fatigue by using an S-N curve having endurable local stress range, Δ σ FAT , at N = 2 × 10 6 cycles to failure equal to 40 MPa and a negative inverse slope, k, equal to 3.

Recent magnesium weldment fatigue test data (Karakas et al., 2008), which involve partial- and full-penetration butt welds, as well as non-load carrying fillet welds, have been analyzed using both traction structural stress and equivalent notch stress methods. Both methods were compared for their effectiveness in correlating the test data by incorporating fracture mechanics-based load ratio parameters and was successfully used in conjunction with the load ratio parameter. Furthermore, the equivalent traction stress parameter, once converted into an equivalent structural strain parameter, enables comparison between magnesium weldment test data with the master S-N curve scatter band adopted in ASME Div. 2. © 2020 Elsevier Ltd

The fatigue behaviour of cold rolled and annealed sheet metals are influenced by the anisotropy of mechanical properties due to crystallographic texture. However, the existing fatigue strain-life models are primarily meant for isotropic material behaviour. In the present work, the Coffin-Manson equation for strain-life is modified to include the effect of anisotropy using phenomenological plasticity models. It is observed that the variation of strain hardening exponent is critical to model the strain-life behaviour. Variation of strain hardening exponent with orientation is modelled using existing anisotropic yield criteria. The prediction of fatigue life using the proposed model correlates well with the experimental results of Al6061-T6 along different orientations. The proposed model can be used to predict the fatigue properties along any orientation from the fatigue data along one orientation and monotonic mechanical properties along longitudinal, transverse and diagonal directions. � 2012 Blackwell Publishing Ltd.

The aim of this investigation was determining the fatigue behaviour of welded aluminium joints and so the appertaining SN-lines by application of Artificial Neural Network (ANN) architectures. For this, fatigue data obtained with aluminium welded joints subjected to constant amplitude loading were used. The main benefit of ANN is the good description of the effects of different factors on fatigue life. The results determined by the ANN method for four aluminium alloys are displayed in scatter bands of SN-lines. It is observed that the trained results are in good agreement with the tested data and enable the estimation of SN-lines. Ziel der Untersuchungen war es die Abschatzung des Schwingfestigkeitsverhaltens von Aluminiumschweisverbindungen und somit der zugehorigen Wohlerlinien mit Hilfe von Kunstlichen Neuronalen Netzen (KNN). Hierzu wurden Ergebnisse zugrunde gelegt, die mit Aluminiumschweisverbindungen aus vier verschiedenen Legierungen unter Einstufenbelastungen ermittelt wurden. Der Vorteil von KNN liegt darin, dass verschiedene Einflussgrosen auf die Lebensdauer zutreffend beschrieben werden konnen. Die mit dieser Methode berechneten Ergebnisse sind in Wohlerlinienstreubandern dargestellt. Durch KNN trainierte und getestete Daten zeigen eine gute Ubereinstimmung und bestatigen den Nutzen dieses Verfahren.

The fatigue performance of composite joints is one of the major concerns for the extensive application of composites in aircraft structures. Accurate assessment of the fatigue life behaviour is crucial and valuable to this end. A wearout model was used to characterize the fatigue life behaviour of composite joint structures. The fatigue data used were selected from the open literature. A data fitting tool, which could deal with small fatigue data sample cases, was developed. The tool could accurately replicate the fitting parameters for S-N curves of single-piece composite cases and was used to study the fatigue life behaviour of adhesively bonded and bolted composite joint cases. Recommendations are made for improving the fatigue assessment capability in composite joint structures using the wearout model., 26th Annual Technical Conference of the American Society for Composites 2011 and the 2nd Joint US-Canada Conference on Composites, 26 September 2011 through 28 September 2011, Montreal, QC

From an engineering point of view, the fatigue strength variability of cast aluminium alloy components requires a detailed understanding of the inconsistency of cast defect distribution. Cast aluminium alloys are not generally homogeneous; they may contain two or more types of common casting defects, which are gas and shrinkage porosities, oxide films, and inclusions. Each defect type has its own distribution of sizes; and multiple cast components of presumably the same material may have different histories and therefore different cast defect populations. A number of statistical analyses of fatigue data assume that a single distribution of casting defect is present uniformly throughout the cast aluminium alloys. As a result, fatigue data are statistically not correctly described. By relaxing the assumptions of a single cast defect distribution, of uniformity throughout the material and of uniformity from specimen to specimen, Weibull statistical analysis for multiple defect distributions have been applied to correctly describe the fatigue life data of aluminium alloy castings having multiple cast defects competing to initiate fatigue cracks.

Discussion Paper / SFB 823; 25/2009

The paper describes procedures to compare the fatigue behaviour of two populations corresponding to batches that differ for a factor on the basis of fatigue data of two samples. Fatigue data are elaborated by means of the maximum likelihood method to obtain the SNP curves and their confidence intervals. The likelihood ratio test is used to identify the most adequate distribution and model. To analyse the influence of the factor, two integrated procedures are adopted: the first one is based on the LR test, the second is an empirical procedure, based on the comparison of the confidence intervals of the curves.