Fracture assessment of a high strength structural steel on the basis of Eurocode 3

This work examines the design method of Eurocode 3 against brittle failure with regard to its application to a high strength structural steel S460N EN 10113 type. The fracture behaviour of the steel is experimentally determined by means of fracture tests, considering also the effects of temperature and plate thickness. A direct verification of the method of Eurocode 3 is made by contrasting the assumptions on which it is based with the actual behaviour of the steel. The failure criterion and the mechanical properties characterizing the resistance to brittle and ductile fracture are the basis of the comparison.

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Résumé La méthode de calcul de l’Eurocode 3 en vue de se garantir du risque de rupture fragile est examinée dans cet article, par rapport à l’application à un acier à haute résistance pour construction métallique (l’acier S460N de la norme EN 10113). Les caractéristiques mécaniques de la rupture de l’acier, en particulier l’influence de la température et de l’épaisseur de laminage, ont été déterminées par des essais de rupture sur éprouvettes préfissurées. La méthod de l’Eurocode 3 a été vérifiée de manière directe en comparant les fondements des règles de calcul au comportement mesuré de l’acier. La comparaison est basée sur le critère de rupture mixte (fragile/ductile) adopté par l’Eurocode et sur les valeurs de tenacité établies à partir des valeurs de la résilience.

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Editorial Note Prof. M. Elices is a Senior Member and a member of the Board of Advisors. He is a member of RILEM TC 147-FMB: Fracture mechanics applications to anchorage and bond, TC 148-SSC: Test methods for the strain softening response of concrete and TC QFS: Size effect and scaling of quasibrittle fracture.     

Cohesive modelling of the fracture of a neutron irradiated pressure vessel steel

The cohesive fracture process zone model was used to account for the neutron irradiation embrittlement of a pressure vessel steel. The tensile testing and fracture of axisymmetrically notched round specimens were numerically modelled assuming a rectangular traction separation law and the irradiation effects were introduced by due modification of this law. The results corroborate those of the experiments performed in a previous work. The cohesive strength and the cohesive energy of the cohesive model were not considered as adjusting parameters, but they were determined from the data of conventional tensile tests and fracture toughness tests on the assumption that the failure of the specimens in these tests also follows the cohesive model.     

The Relations of Problem Behavior Status to Children's Negative Emotionality, Effortful Control, and Impulsivity: Concurrent Relations and Prediction of Change.

The relations of children's internalizing and externalizing problem behaviors to their concurrent regulation, impulsivity (reactive undercontrol), anger, sadness, and fearfulness and these aspects of functioning 2 years prior were examined. Parents and teachers completed measures of children's (N = 185; ages 6 through 9 years) adjustment, negative emotionality, regulation, and behavior control; behavioral measures of regulation also were obtained. In general, both internalizing and externalizing problems were associated with negative emotionality. Externalizers were low in effortful regulation and high in impulsivity, whereas internalizers, compared with nondisordered children, were low in impulsivity but not effortful control. Moreover, indices of negative emotionality, regulation, and impulsivity with the level of the same variables 2 years before controlled predicted stability versus change in problem behavior status. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Calcium and fluoride release from ion exchange polyphasic systems

The present study concerns the kinetics of ion exchange accompanied by CaF₂ precipitation in tri‐phasic and quadri‐phasic systems involving a weak base anionic exchanger and a carboxylic cationic exchanger in the F^? and Ca²⁺ forms, respectively, in contact with a solution of artificial saliva. It was shown that in both systems the rate of Ca²⁺ release from the cationic exchanger is much lower than that of F^? from the anionic one. The rate of release for both ions, controlled by intraparticle diffusion, has been characterized by a Fick's law model. The kinetic parameters of effective rate of release (B) and diffusion coefficient (D) of the respective ion in the resin phase depend on the type of resin and the presence of different numbers of phases. The amount of the precipitate crystallizing on the surface of the resin beads depends on the type of the ion exchange resin, its particle size and on the ratio of resin components. By varying this ratio and the particle size of the ion exchangers it is possible to accomplish the precipitation mostly on the larger surface of the ionic exchanger. Copyright © 2003 Society of Chemical Industry     

Indirect determination of carbohydrates in wort samples and dietetic products by capillary electrophoresis

The first total separation by electrophoresis of five carbohydrates, sucrose, maltotriose, maltose, glucose and fructose, is described. The basic technique requires 1‐naphthylacetic acid as background electrolyte at pH 12.5, indirect UV detection at 222 nm, with a capillary of 75 µm × 120 cm and a voltage of 25 kV. Linear calibration curves from 50 to 400 mg l^?1 with a good correlation coefficient were obtained. The method has been used to determine carbohydrates during the brewing process of a non‐alcoholic beer and also to analyse the carbohydrate content of dietetic fruit juices and chocolate. Copyright © 2004 Society of Chemical Industry     

Assessment of heavy metals remobilization by fractionation: comparison of leaching tests applied to roadside sediments

The pollution emitted by traffic activities and road maintenance is an area of great interest as contaminants can be transported to roadside sediments and pose a risk to environmental and human health. In the presentwork, deposited pollution in roadside sediments has been assessed by sampling along a highly traveled highway in Barcelona and the surrounding area. The available amounts of the heavy metals was determined by applying different leaching tests and calculating the concentration enrichment ratio (CER) and the environmental concentration guideline values (ECG). To gain information on the heavy metals (HMs) fractionation, the sequential extraction scheme (SES), established by the Standard Measurement and Testing (SM&T), was implemented, and the results were compared with those obtained by single leaching tests. An anthropogenic enhancement of certain metals was observed after considering both the CER and ECG values. However, if only ECG values were considered, an overestimation of the anthropogenically enhanced pollutants was obtained due to disregarding geochemical and particle size variability. CER values provide a more realistic assessment by determining different levels of anthropogenic impact. Thus, CER values suggest a minimum anthropogenic apportion for metals such as Cd, Cr, and Ni, whereas different situations from significant to extreme anthropogenic contribution were observed for Zn, Pb, and Cu. These results have been complemented by other leaching tests that minimize the time-consuming environmental evaluation. In this study, HCI extraction produces suitable results for a quick screening since they correlate well with the corresponding SES: Cu(r2 = 0.798), Pb(r2 = 0.958) and Zn(r2 = 0.901). Mild extractants have been observed to be limited to highly polluted samples due to their low leaching power. The information obtained following this procedure helps to identify hazardous areas that need a remedial strategy.     

Investigation of the multiaxial fatigue behaviour of 316 stainless steel based on critical plane method

In this work, the multiaxial behaviour of 316 stainless steel is studied under the lens of critical plane approach. A series of experiments were developed on dog bone–shaped hollow cylindrical specimens made of type 316 stainless steel. Five different loading conditions were assessed with (a) only tensile axial stress, (b) only hoop stress, (c) combination of axial and hoop stresses with square shape, (d) combination of tensile axial and hoop stresses with L shape, and (e) combination of compressive axial and hoop stresses with L shape. The fatigue analysis is performed with four different critical plane theories, namely, Wang‐Brown, Fatemi‐Socie, Liu I, and Liu II. The efficiency of all four theories is studied in terms of the accuracy of their life predictions and crack failure plane angle. The best fatigue life predictions were obtained with Liu II model, and the best predictions of the failure plane were obtained with Liu I model.     

Estimation of the opening load under variable amplitude loading

The crack opening/closure load concept is widely used to justify the fatigue crack growth behaviour with different load ratios and the load interaction effects. Many experimental techniques have been proposed to measure crack opening/closure load, and amongst them, compliance offset methods are widely used for their simplicity and consistency. In this paper, a modification of the ASTM method is proposed. The new method has a more general applicability as it can be applied to broadband variable amplitude loads. The method is described in detail and is applied on a 2024‐T351 aluminium alloy. The good correlation of the opening load estimated with the new method and the strip‐yield model implemented in Nasgro indicates that the new method could be used as an alternative for the cases where complex variable amplitude loads occur.     

Heavy metal removal by microalgae

The liver is one of the principal sites of iron overload in diseases such as hemochromatosis and beta thalassemia. Hence, much effort has been invested in examining the mechanisms of Fe uptake by hepatocytes. In the present study we have examined the effect of small molecular weight (M(r)) Fe complexes on Fe uptake from iron 59-labeled transferrin (Tf) and 59Fe-labeled citrate by primary cultures of hepatocytes. This was important to assess because Fe-citrate and saturated diferric Tf coexist in the serum of patients with untreated Fe overload. Preincubation of hepatocytes with the low-M(r) Fe complex ferric ammonium citrate (FAC; 25 microg/mL; (Fe) = 4.4 microg/mL) followed by incubation with 59Fe-Tf or 59Fe-citrate ((Fe) = 0.25 to 25 micromol/L) resulted in the marked stimulation of 59Fe uptake. For example, at a physiologically relevant Tf-Fe concentration of 25 micromol/L, there was an 8-fold increase in 59Fe uptake by cells incubated with FAC compared to control cells. In contrast, at Tf-Fe concentrations of 0.25 to 2.5 micromol/L, 59Fe uptake in FAC-treated cells was only 1-fold to 3-fold greater than that in the corresponding controls. These data suggest that the FAC-activated Fe uptake process predominates at physiologically relevant Tf concentrations above the saturation of the Tf receptor (TfR). This is the first study to demonstrate that preincubation of hepatocytes with Iow-M(r)Fe complexes can markedly increase Fe uptake from diferric Tf. In conclusion, these results may help to explain the loading of hepatocytes with Fe that occurs in Fe-overload disease despite marked down-regulation of the TfR.