Reclassification of Spheroidal Graphite Ductile Cast Irons Grades According to Design Needs

AbstractThe classification of grades inside a material family should be based on the properties required by design procedures. This paper proposes a reclassification of spheroidal graphite ferritic pearlitic and ausferritic (ADI) ductile cast irons grades based on yield strength (YS), strength ratio (SR) UTS/YS and elongation at fracture (EF). In fact, these parameters are fundamental for the static assessment according to the procedures FKM Guideline and BS 7910:2005. Static assessment at room temperature, involving plastic deformation and depending on the wall thickness and stress state triaxiality, is here proposed as the most significant for the material classification. All other properties (e.g., fatigue under cyclic loads, high strain rates and temperature effect, etc.) should be reported with reference to the classification mentioned above. SR and EF control the plastic deformation at the notch tip, where maximum calculated elastic stress is redistributed. Minimum YS is usually assumed as the basic parameter for static and cyclic loading design. Because of the inverse relationship that exists between strength and ductility, Brinell hardness control and material quality index should be adopted as Material Quality Control tools, preventing from a too low EF. Fracture Toughness and its ratio with YS must be considered for preventing brittle fracture due to the presence of flaws. Fracture toughness definitions and available data are not sufficiently consistent for a correct comparison between different material grades. A surrogate Charpy energy measurement is indicated for an indirect estimate of toughness

Erosión por contracción y por estribo en puentes aliviadores en valle de inundación

En el presente trabajo se analiza, en forma experimental, la interrelación existente entre los distintos tipos de erosión que se producen en puentes aliviadores, y sus vinculaciones con los parámetros característicos del escurrimiento. A tales fines se llevó a cabo una secuencia de ensayos de laboratorio, destinados especialmente a evaluar las modificaciones que sufre la distribución de caudales como consecuencia del desarrollo de la erosión por estribo, y la incidencia que ello tiene sobre la erosión por contracción. Los resultados alcanzados demuestran que la reducción del porcentaje de caudal, en la zona no afectada por la hoya de erosión local, es función de la profundidad de socavación debida a la presencia del estribo. Sobre esta base se propone una secuencia de cálculo de las erosiones totales en un puente aliviador en valle de inundación, la cual reproduce adecuadamente valores medidos en prototipo durante la ocurrencia de una crecida extraordinaria

A Contribution to New Material Standards for Ductile Irons and Austempered Ductile Irons

Some results of materials characterization activities, dedicated to classical and notch mechanics fatigue and elastoplastic properties, have already been published for some Ferritic–Pearlitic Ductile Iron, including the patented heat treated Isothermed (IDI) and Austempered Ductile Iron (ADI) grades. Others have not yet been published. The possible use of all of these results in new standards is discussed in this paper. It is proposed that new standards should provide a criterion that is able to measure the process quality that represents more accurately the actual market needs and manufacturing capabilities. Classification of grades, considered by existing standards, is based on minimum properties for strength and ductility parameters that are separately evaluated. A different approach that is based on a quality index, which considers strength and ductility all in one, is proposed. However, this new proposed approach may not be sufficient to provide a satisfactory classification for the ADIs. This is because their fracture mechanical behavior and machinability can be correlated with their austenite stability. It could also be insufficient for the classification of the recent High Silicon Solid Solution Strengthened Ductile Irons that exhibit a decreasing ultimate tensile strength/proof stress ratio with increasing Si. For construction steels, fracture mechanics properties are sometimes believed to be related to the Charpy impact energy. This paper introduces an innovative practical and inexpensive data analysis, performed on the tensile test curve, which appears to be a potential estimator of fracture mechanical properties, at least for ADIs, where said properties could be correlated with the austenite stability

Comparison among Different Constitutive Equations on Investigating Tensile Plastic Behavior and Microstructure in Austempered Ductile Iron

The capabilities of different constitutive equations of approximating the tensile flow curves and correlating plastic behavior with the microstructure were investigated in austempered ductile iron ADI 1050. In a previous paper, the microstructure evolution of ADI 1050 during austempering was investigated through quenching the ADI 1050 after 14 increasing austempering times to room temperature. The 14 samples were tensile tested and two classes of constitutive equations were examined in the present paper. The Hollomon-type constitutive equations approximated all of the tensile flow curves of ADI 1050 very well but failed in correlating the plastic behavior with microstructure evolution. Voce-type constitutive equations approximated the tensile flow curves only at high stresses very well but could correlate the plastic behavior with the microstructure evolution of ADI 1050 during austempering excellently. The reason of this success was rationalized in terms of the physical basis of Voce-type equations, while Hollomon-type equations are empirical

Oxidized/deamidated-ceruloplasmin dysregulates choroid plexus epithelial cells functionality and barrier properties via RGD-recognizing integrin binding.

Abstract Choroid plexus epithelial cells (CPEpiCs) determine the composition of cerebrospinal fluid (CSF) and constitute the blood-CSF barrier (BCSFB), functions that are altered in neurodegenerative diseases. In Parkinson's disease (PD) the pathological environment oxidizes and deamidates the ceruloplasmin, a CSF-resident ferroxidase, which undergoes a gain of RGD-recognizing integrin binding property, that may result in signal transduction. We investigated the effects that oxidized/deamidated ceruloplasmin (Cp-ox/de) may exert on CPEpiCs functions. Through RGD-recognizing integrins binding, Cp-ox/de mediates CPEpiCs adhesion and intracellular signaling, resulting in cell proliferation inhibition and alteration of the secretome profile in terms of proteins related to cell-extracellular matrix interaction. Oxidative conditions, comparable to those found in the CSF of PD patients, induced CPEpiCs barrier leakage, allowing Cp-ox/de to cross it, transducing integrins-mediated signal that further worsens BCSFB integrity. This mechanism might contribute to PD pathological processes altering CSF composition and aggravating the already compromised BCSFB function

Erosión por contracción y por estribo en puentes aliviadores en valle de inundación

[ES] En el presente trabajo se analiza, en forma experimental, la interrelación existente entre los distintos tipos de erosión que se producen en puentes aliviadores, y sus vinculaciones con los parámetros característicos del escurrimiento. A tales fines se llevó a cabo una secuencia de ensayos de laboratorio, destinados especialmente a evaluar las modificaciones que sufre la distribución de caudales como consecuencia del desarrollo de la erosión por estribo, y la incidencia que ello tiene sobre la erosión por contracción. Los resultados alcanzados demuestran que la reducción del porcentaje de caudal, en la zona no afectada por la hoya de erosión local, es función de la profundidad de socavación debida a la presencia del estribo. Sobre esta base se propone una secuencia de cálculo de las erosiones totales en un puente aliviador en valle de inundación, la cual reproduce adecuadamente valores medidos en prototipo durante la ocurrencia de una crecida extraordinaria.A la Universidad Nacional del Litoral quien financió, por medio de los Cursos de Acción para la Investigación y Desarrollo (CAI+D), el Proyecto de Investigación en el marco del cual se desarrolló este trabajo. Al Ingeniero Mario L. Amsler, por su revisión crítica del manuscrito original.Schreider, M.; Zanardi, L.; Scacchi, G.; Franco, F. (1998). Erosión por contracción y por estribo en puentes aliviadores en valle de inundación. Ingeniería del Agua. 5(2):23-34. https://doi.org/10.4995/ia.1998.2747SWORD233452Blench, T., (1969) Mobile-bed fluviology. University of Alberta Press, Canada, 168 p.Chow, V.T., (1959) Open Channel Hydraulic. McGraw-Hill Book Company, New York, 680 p.Dongol, D. M. S., (1994) Local scour at bridge abutment. Report N° 544, Department of Civil Engineering, University of Auckland, Auckland, 410 p.Juarez Badillo, E. y Rico Rodriguez, A., (1984) Mecánica de Suelos. Tomo III, Flujo de Agua en Suelos, Editorial Limusa, 414 p.Kandasamy, J.K., (1989) Abutment scour, School of Engineering Report N° 458, University of Auckland, Auckland, 278 p.Laursen, E. M., (1960) Scour at bridge crossings, Proceedings ASCE 86 (HY 2). pp. 39 - 54.Laursen, E. M., (1963) Analysis of relief bridges scour, ASCE, Journal of the Hydraulics Division, vol. 89, HY 3, pp. 93-118.Molinas, A., (1994) Bridge stream tube model for alluvial river simulation (BRISTARS). User Manual. National Cooperative Highway Research Program, Project N° HR15-11A, Transportation Research Board, Washington, D.C., 82 p.Prendes, H., Amsler, M.L., Schreider, M.I., Huespe, J.,Cian, C. y Lima, D., (1992) Metodología para calcular el volumen sedimentado en un paso de navegación, Anales de XV Congreso Latinoamericano de Hidráulica. Cartagena, Vol. 3, pp. 195-205.Richardson, E.V., Simons, D.B. y Julien, P., (1990) Highwayin the river enviroment. FHWA-HI -90-016, Federal Highway Administration, U.S. Department of Transportation, Washington, D.C. 549 p.Schreider, M., Zanardi, L., Scacchi, G. y Franco, F., (1996) Interacción entre la erosión por contracción y por estribo en puentes aliviadores en valle de inundación - Estudio experimental, Anales del XVII Congreso Latinoamericano de Hidráulica. Guayaquil, Vol 4, pp. 363 - 374.Shearman, J.O., (1987) Bridge waterways analysis model for mainframe and microcomputers. WSPRO/ HY-7, Federal Highway Administration,U.S. Department of Transportation, Washington, D.C., 177 p. U.S. Department of Transportation, (1993) Hydraulic Engineering Circular, N° 18, Evaluating scour at bridges. 2° Edition. Report N° FHWA-IP-90-017, Federal Highway Administration, Washington, D.C. 132 p

Evaluation of Microstructure Quality in Ductile Irons Based on Tensile Behaviour Analysis

Dislocation-density-related equations were proved to be promising tools to correlate tensile plastic behaviour and microstructure in ductile irons (DIs), revealing distinct relationships between equation parameters and microstructure features in austempered ductile irons (ADI) and isothermed ductile irons (IDI). These equations resulted to be successful also in the characterization of the austempering process through the plastic behaviour analysis of tensile tests of an ADI 1050 that was quenched at different times during austempering. The equation parameters could indeed be correlated to the time window for the best ausferrite, and could predict the precipitation of the deleterious ε' carbides for long austempering times. In the present work the results of the tensile plastic behaviour analysis of different DIs through dislocation-density-related equations are reported. The aim of the analysis was to test the capability of these equations to assess the microstructure quality of DIs and support their industrial production

electrochemical sensing of glucose by chitosan modified graphene oxide

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The Bostrichidae of the Maltese Islands (Coleoptera)

The Bostrichidae of the Maltese Islands are reviewed. Ten species are recorded with certainty from this Archipelago, of which 6 namely, Trogoxylon impressum (Comolli, 1837), Amphicerus bimaculatus (A.G. Olivier, 1790), Heterobostrychus aequalis (Waterhouse, 1884), Sinoxylon unidentatum (Fabricius, 1801), Xyloperthella picea (A.G. Olivier, 1790) and Apate monachus Fabricius, 1775 are recorded for the first time. Two of the mentioned species (H. aequalis and S. unidentatum) are alien and recorded only on the basis of single captures and the possible establishment of these species is discussed. Earlier records of Scobicia pustulata (Fabricius, 1801) from Malta are incorrect and should be attributed to S. chevrieri (A. Villa & J.B. Villa, 1835). A zoogeographical analysis and an updated checklist of the 12 species of Bostrichidae recorded from the Maltese Islands and neighbouring Sicilian islands (Pantelleria, Linosa and Lampedusa) are also provided. Rhizopertha dominica (Fabricius, 1792) form granulipennis Lesne in Beeson & Bhatia, 1937 from Uttarakhand (northern India) was overlooked by almost all subsequent authors. Its history is summarized and the following new synonymy is established: Rhizopertha dominica (Fabricius, 1792) form granulipennis Lesne in Beeson & Bhatia, 1937 = Rhyzopertha dominica (Fabricius, 1792), syn. n. Finally, records of Amphicerus bimaculatus from Azerbaijan, of Bostrichus capucinus (Linnaeus, 1758) from Jordan and Syria, of Scobicia chevrieri from Jordan and Italy, of Xyloperthella picea from Italy, and of Apate monachus from Corsica (France) and Italy, are also provided.peer-reviewe

The Correlation between Solidification Rates, Microstructure Integrity and Tensile Plastic Behaviour in 4.2 wt.% Silicon Strengthened Ductile Iron

High Silicon Strengthened Ductile Iron (HSiSDI) with 4.2 wt.% of silicon was produced in Y-blocks with different thicknesses to investigate the effects of the solidification rate on microstructure integrity and tensile mechanical properties. With decreasing solidification rates, the graphite degeneracy with the appearance of chunky graphite became more significant at the highest silicon contents, so chemical ordering and graphite degeneracy seemed to be qualitative explanations of tensile property degradation. However, a deeper analysis of the relationship between solidification rate, microstructure and tensile properties was realized through an innovative approach based on the Matrix Assessment Diagram (MAD), where the parameters of Voce equation resulting from best-fitting the experimental tensile flow curves of a significant number of HSiSDI samples, were plotted. For 3.5 wt.% silicon content, the MAD analysis indicated that the microstructure was sound for any solidification rate, while for 4.5 wt.% the microstructure was sound only for the fastest solidification rates. For 4.2 wt.% silicon content the MAD analysis pointed out that the tensile plastic behaviour and the microstructure integrity was in between the 3.5 and 4.5 wt.% silicon contents, representing a composition threshold where the reliable microstructures were only found with the fastest solidification rates, while considerable variability was found for the slowest ones. Support to the MAD analysis results was given from microstructure observations