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Letteratura scientifica selezionata sul tema "R-curve"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 9 febbraio 2022

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Articoli di riviste sul tema "R-curve"

Ghadirdokht, A., e M. Heidari-Rarani. "Delamination R-curve behavior of curved composite laminates". Composites Part B: Engineering 175 (ottobre 2019): 107139. http://dx.doi.org/10.1016/j.compositesb.2019.107139.

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Sarkar, Debasish, Bikramjit Basu, Min Cheol Chu e Seong Jai Cho. "R-curve behavior of Ti3SiC2". Ceramics International 33, n. 5 (luglio 2007): 789–93. http://dx.doi.org/10.1016/j.ceramint.2006.01.002.

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Wolfenden, A., HS Pearson e DE McCabe. "R-Curve Round-Robin Program for ASTM Recommended Practice for R-Curve Determination (E 561)". Journal of Testing and Evaluation 14, n. 4 (1986): 191. http://dx.doi.org/10.1520/jte11261j.

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Farnsworth, David L. "Axes for symmetric convex curves". Mathematical Gazette 102, n. 553 (8 febbraio 2018): 23–30. http://dx.doi.org/10.1017/mag.2018.4.

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Curves are given in polar coordinates (r, θ)by equations of the form r = f (θ), where for f (θ) > 0 all θ. Consider curves which are symmetric about the origin O, so that, f(θ + π) = f (θ) for all θ. For such a curve, its interior is the set {(r, θ) : 0 ≤ r ≤ f (θ)}. Further, assume that the curve is convex. Recall that a closed curve is convex if a line segment between any two of its points has no points exterior to the curve [1], [2, pp. 198-203]. We call these curves M-curves, because the curves are fundamental objects in Minkowski geometry, where they are called Minkowski circles or simply circles [3, 4]. That application is briefly discussed in the Section 4 but is not required for our purposes.Examples of M-curves are displayed in Figures 1 to 6. In order to express these curves as functions in rectangular coordinates, we need axes.

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Jiang, Zhengwen, Shui Wan, Thomas Keller, Zhi Fang e Anastasios P. Vassilopoulos. "Influence of curved delamination front on R-curve of DCB specimen". Composite Structures 227 (novembre 2019): 111311. http://dx.doi.org/10.1016/j.compstruct.2019.111311.

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Bujalance, E., G. Gromadzki e M. Izquierdo. "On real forms of a complex algebraic curve". Journal of the Australian Mathematical Society 70, n. 1 (febbraio 2001): 134–42. http://dx.doi.org/10.1017/s1446788700002329.

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AbstractTwo projective nonsingular complex algebraic curves X and Y defined over the field R of real numbers can be isomorphic while their sets X(R) and Y(R) of R-rational points could be even non homeomorphic. This leads to the count of the number of real forms of a complex algebraic curve X, that is, those nonisomorphic real algebraic curves whose complexifications are isomorphic to X. In this paper we compute, as a function of genus, the maximum number of such real forms that a complex algebraic curve admits.

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Rödiger, Stefan, Alexander Böhm e Ingolf Schimke. "Surface Melting Curve Analysis with R". R Journal 5, n. 2 (2013): 37. http://dx.doi.org/10.32614/rj-2013-024.

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Srinivasan, S., e R. O. Scattergood. "R-curve measurements in PSZ ceramics". Journal of Materials Research 5, n. 7 (luglio 1990): 1490–95. http://dx.doi.org/10.1557/jmr.1990.1490.

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An indentation-bend failure-stress method was used for measurement of R-curves in a series of PSZ ceramics with varying peak toughness. Dilatational transformation-stress constraints are included in the residual-stress driving force contribution to the applied stress intensity factor. A power-law fit to the form of the R-curve simplifies the analysis. While the resulting curves show the expected form, measured toughness values are high relative to the expected peak toughness. Limitations and the range of applicability of the indentation-bend technique are discussed.

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Rosa, V., K. A. Fukushima, M. Borba, H. N. Yoshimura e P. F. Cesar. "R-curve behavior of dental porcelains". Dental Materials 27 (gennaio 2011): e72. http://dx.doi.org/10.1016/j.dental.2011.08.568.

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Vekinis, G., M. F. Ashby e P. W. R. Beaumont. "R-curve behaviour of Al2O3 ceramics". Acta Metallurgica et Materialia 38, n. 6 (giugno 1990): 1151–62. http://dx.doi.org/10.1016/0956-7151(90)90188-m.

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Tesi sul tema "R-curve"

Dourado, Nuno Miguel Moura Marcelo de Valentin Gérard. "R-Curve behaviour and size effect of a quasibrittle material wood /". S. l. : S. l. : Bordeaux 1 ; Universidade do Porto (Portugal), 2008. http://ori-oai.u-bordeaux1.fr/pdf/2008/DOURADO_NUNO_2008.pdf.

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Thèse de doctorat : Sciences physiques et de l'ingénieur. Mécanique : Bordeaux 1 : 2008. Thèse de doctorat : Sciences physiques et de l'ingénieur. Mécanique : Universidade do Porto (Portugal) : 2008.
Titre provenant de l'écran-titre.

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Dourado, Nuno Miguel. "R-Curve behaviour and size effect of a quasibrittle material : wood". Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13734/document.

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Ce travail concerne des expériences mécaniques, des analyses numériques et des modélisations analytiques de la rupture cohésives (Mode I), vis-à-vis de l’étude du comportement mis en évidence par la courbe de Résistance (Courbe-R) et l’effet d’échelle de structures entaillées en bois massif. Des expériences de fissuration sont combinées à des analyses numériques pour déterminer les propriétés de rupture au moyen d’une procédure appelée Théorie de la Mécanique de la Rupture Linéaire Élastique équivalente (TMRLE), basée sur la complaisance de la structure. La courbe-R, obtenue à partir des expériences, selon une méthode de correction du poids propre, montre l’existence d’un domaine endommagé (Zone de Processus de Rupture) de taille non négligeable se développant en fond de fissure. Dans des conditions de fissuration stationnaire, ce domaine atteint une taille critique, et l’énergie nécessaire pour faire propager la fissure avec ce domaine endommagé (par unité de surface de rupture), reste constante. Le taux de libération de l’énergie de fissuration ainsi attendu, joue un rôle important en Mécanique de la Rupture, car il est possible simuler le comportement quasi-fragile du matériau en combinaison avec les autres propriétés de cohésion. La loi d’effet d’échelle de Bažant, utilisée pour prévoir l’influence de la taille sur la contrainte nominale, est estimée à partir de la réunion de deux comportements asymptotiques réalisés sur de petites tailles (Analyse limite ou RdM) et des grandes tailles. Une procédure analytique est présentée pour évaluer le comportement asymptotique additionnel exhibé par la contrainte nominale dans le régime intermédiaire, de façon plus exacte. Une validation numérique est présentée, et l’information expérimentale vient confirmer ce comportement asymptotique
This work concerns the mechanical testing, numerical analysis and modelling of cohesive fracture (Mode I) on the purpose to study the Resistance-curve behaviour and the size effect in wooden notched structures. The mechanical testing is combined with the numerical analysis to evaluate fracture properties by means of an equivalent LEFM approach based on the structure compliance. The Resistance-curve being revealed from the experiments, by means of a self-weight compensation method, correction puts into evidence that a non-negligible damaged domain (Fracture Process Zone) is under development in the crack front during the loading process. This being the case, among other fracture parameters issued from the Resistance-curve, the critical (asymptotic) energy release rate is determined, turning possible to use it in combination with other cohesive crack properties in the crack modelling (in Mode I). Thus, for a given geometry it is possible to monitor the critical dimension being revealed by the Fracture Process Zone (FPZ) during the crack propagation. The well known Bažant’s size effect law provides the scaling of the nominal strength through the asymptotic matching performed both on the small (Strength Theory) and on the large (LEFM) structure sizes. An analytical procedure is proposed to determine an additional asymptotic regime in the intermediate size range through a more accurate manner. Numerical validations of the proposed procedure are made and experimental data is presented revealing the scaling of the nominal strength through an envelop of values

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Bernardini, Chiara. "Un risultato di h-principle per curve a curvatura costante in R^n". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21250/.

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Oggetto di questa tesi è mostrare che ogni curva liscia immersa nello spazio euclideo n-dimensionale, può essere deformata in una curva con curvatura costante, mediante una perturbazione arbitrariamente piccola della curva iniziale e delle sue rette tangenti. Tale valore costante della curvatura deve essere maggiore o uguale del massimo della curvatura della curva iniziale, e si dimostra che tale limite inferiore è ottimale. Questo significa che le curve lisce di curvatura costante, soddisfano, secondo la terminologia di Gromov, il `relative C^1-dense h-principle' nello spazio delle curve immerse in R^n.

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Cheung, C. M. S. "The R-curve approach for the fracture assessment of an aluminium alloy bridge". Thesis, Swansea University, 2001. https://cronfa.swan.ac.uk/Record/cronfa42424.

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A result of fatigue testing on a full scale aluminium alloy bridge, which is used by the military for temporary crossings, showed an unexpected increase in fracture resistance, compared with its plane strain K[IC]. This increase was due to a combination of low constraint and large stable crack extension in the bridge components. Previous work had attributed the increase to the loss of constraint alone, but the present work shows stable cracking is equally important. The effect of stable cracking in the bridge alloy was first examined experimentally in large 25mm thick 3PB specimens which were analysed numerically using the finite element method. The numerical 2-D results provided a concave J[R]-curve showing that dJ[R]/da rises increasingly with crack extension. This increase is associated with the transition from flat to slant fracture in the experimental test pieces, due to the loss of plane strain constraint. Fracture assessment using the R-curve approach showed that long cracks, both in large fracture mechanics specimens and the bridge girder, are stable because, although for a given load, G=J[R], dG/dadJ[R]/da when G=J[R]. The J[R]-curve for low constraint geometries should be indexed by the T-stress. The fatigue crack growth rate for the bridge alloy, taken from different sources, was compared. The Paris law index was nearly 4 for large CT and tension specimens, but only about 2 from fatigue tests on a full-scale bridge. For a large tension specimen, the corresponding K[IC] at the change in index was delayed from 35 (the plane strain K[IC] value) to 48MPa√m, because of the effect of low constraint. A simple model based on the J[R]-curve (at initiation) was developed for predicting crack extension under high cyclic load (K[max] > K[IC]), but with limited success.

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Heinrich, Benedikt [Verfasser], e Heinrich von [Akademischer Betreuer] Weizsäcker. "Curve interactions in R^2: An analytical and stochastical approach / Benedikt Heinrich. Betreuer: Heinrich von Weizsäcker". Kaiserslautern : Technische Universität Kaiserslautern, 2013. http://d-nb.info/1044294183/34.

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Colafemea, Angelo Antonio. "Modelamento numérico da técnica de normalização linear para determinação de curvas J-R". Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-20092016-115454/.

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Neste trabalho os resultados da metodologia de normalização de E. D. Reese e K. H. Schwalbe para a obtenção de curvas J-R, são comparadas com aquelas obtidas pela tradicional Técnica de Variação de Flexibilidade Elástica. Ambos os métodos foram aplicados à um aço de grau nuclear A508-CL3A, quando vários corpos-de-prova miniaturizados 0.394TC[S], foram testados em temperaturas típicas de operação de vasos de pressão nuclear. Corpos-de-prova miniaturizados formam tratados termicamente tentando simular o comportamento exibido pelos aços estruturais quando submetidos à diferentes níveis de exposição de nêutrons, sendo que outros foram ensaiados na condição de como-recebidos. Todos os procedimentos experimentais e analíticos empregados neste estudo foram totalmente computadorizados, incluindo aquisição e refinamento dos dados e o traçado da curva J-R. Esta última foi realizada conforme a mais recente versão das normas ASTM, denominada ASTM-E1820. As variáveis avaliadas influentes do comportamento das curvas de J-R, incluem o incremento de propagação de trinca e o número de pontos de dados de carga versus deslocamento. Também foi analisada a efetividade do método de normalização quando comparada com a técnica de variação de flexibilidade elástica. Os resultados desta pesquisa mostraram que a normalização é uma metodologia confiável e muito simples, tão logo a programação de software seja desenvolvida, para ser aplicada em uma vasta variação de comportamentos mecânicos como amostrados neste estudo.
In this research, results from Reese; Schwalbe (1993) linear normalization methodology for deriving J-R curves are compared to those obtained from the traditional unloading elastic compliance technique. Both methodologies were applied to a nuclear grade steel A508-CL3A. Several miniaturized 0.394TC[S] specimens, were tested at typical NPV operating temperatures. Small scale testpieces were heat treated aiming to simulate the embritlemment exhibited by the structural steel when submitted to different levels of neutron exposure, whereas other specimens were tested in the as-received condition. All experimental and analytical procedures employed in this study have been fully computerized, including data acquisition, data refinement and J-R curve plotting, when the guidelines supplied by most recent version of ASTM standard for J-R curves, namely ASTM-E1820, were followed. The assessed variables affecting J-R curves behavior comprised crack propagation increment, number of load-Ioad line displacement data points, and it was also analyzed the agreement of the normalization method when compared to the compliance technique. Research results have shown that linear normalization is a trustworthy and very simple methodology to be applied in a vast range of mechanical behavior as sampled in this study, as long as computer programming is employed.

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Zúñiga, Munizaga Andrés Jahir. "Entire solutions to the inhomogeneous allen-cahn equation in R^2, with a transition on a noncompact curve". Tesis, Universidad de Chile, 2012. http://www.repositorio.uchile.cl/handle/2250/111186.

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Ingeniero Civil Matemático
Este trabajo de memoria de título presenta un estudio de la ecuación de perturbación singular de Allen-Cahn con inhomogeneidad: \begin{equation}\ep^2\div\left(a(x)\cdot\nabla_{x}u(x)\right)+a(x)f(u(x))=0,\quad\text{ en }\quad\R^2 \label{AllenCahnEq}\end{equation} donde $\varepsilon>0$ es un parámetro pequeño, $a(x)$ es un potencial uniformemente positivo y suave, que induce una forma de medir distancias para puntos en $\R^2$, y $f$ es la nolinealidad dada por $f(u)=u-u^3$. El estudio aborda la construcción de soluciones enteras de~\eqref{AllenCahnEq}, bajo la condición que $u$ se anule cerca de una curva $\Gamma\subset \R^2$. El enfoque propuesto asume que $\Gamma$ es una curva no acotada, geodésica no-degenerada relativa al funcional de longitud de arco $\int_{\Gamma}a(\vec{x})$, con curvatura $k_{\Gamma}$ suave que decae a una tasa polinomial. Es de interés el estudio de la ecuación de Allen-Cahn con presencia de un término de inhomogeneidad $a(x)\not\equiv 1$, ya que esto conlleva el estudio de curvas geodésicas para una métrica no trivial de $\R^2$. Además, es relevante considerar que el conjunto nodal de $u$ yace cerca de una curva no acotada, pues esto se refleja en el estudio de ecuaciones diferenciales en contextos no compactos. El resultado principal asegura la existencia de una solución de~\eqref{AllenCahnEq}, la cual converge exponencialmente a $\pm 1$ cuando $x$ se aleja de $\Gamma$. Un segundo resultado entrega ejemplos de potenciales $a(x)$ y curvas $\Gamma$, para los cuales es posible construir una solución $u$ con el comportamiento antes descrito. La demostración de este resultado está basada en una técnica conocida como reducción infinito dimensional de Lyapunov-Schmidt, la cual motiva a la elección de un candidato a solución del tipo $u = w + \phi$, donde $w$ en coordenadas adecuadas resuelve $w''+f(w)=0$, y determina el perfil de $u$ a orden principal. Además $\phi$ es una función de corrección, con el fin de convertir a $u$ en solución exacta de~\eqref{AllenCahnEq}, lo que obliga a $\phi$ a resolver una ecuación diferencial no lineal. De ahí en más, el problema consiste en estudiar la existencia y unicidad de la última ecuación en un espacio funcional adecuado. Esto se realizó analizando el operador linealizado asociado a la ecuación de Allen-Cahn, y luego el problema no-lineal que es resuelto mediante un esquema de punto fijo. Para el ultimo análisis, fue necesario ajustar $\Gamma$ en un parámetro de perturbación $h$, lo que equivale a una EDO no lineal en $h$ donde participa la segunda variación del funcional de largo $l_{a,\Gamma}$ asociado a $\int_{\Gamma}a(\vec{x})$. Finalmente, el método utilizado no sólo provee la existencia de una solución $u$ de~\eqref{AllenCahnEq}, sino que además entrega una caracterizacón completa de ésta, tanto en tamaño como en comportamiento cualitativo en coordenadas relacionadas a la curva $\Gamma$.

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Pásztor, Bálint. "Analýza přežití v R". Master's thesis, Vysoká škola ekonomická v Praze, 2015. http://www.nusl.cz/ntk/nusl-202126.

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Survival analysis is a statistical discipline that analyzes the time to occurrence of certain events. The aim of this thesis is to describe the possibilities of survival analysis in the environment of statistical software R. Theoretical knowledge is applied to real data, parametric and nonparametric estimates of survival functions are evaluated by different methods and compared with each other. In the section focusing on nonparametric models Kaplan-Meier and Nelson-Aalen functions are described. Among the parametric estimates there were included well-known probability distributions, survival functions and risk functions derived from these distributions are presented and there is discussed their usefulness in survival analysis. Another aim is to show the possibility of deriving transition probabilities from estimates and building a Markov chain model to capture the changes of studied cohort over time. The second part of the work contains a description of the applications of the theory of survival analysis. In this section there are shown possibilities of statistical modeling in the field of survival analysis using the software R. Outputs from R were used to create Markov model. There are presented possibilities of pharmacoeconomic models and description of the basic concepts of HTA. Cost-effectiveness calculations using ICER were conducted in accordance with the methodology of SUKL. It was shown that the statistical modelling of survival plays an important role in the evaluation of the cost-effectiveness of medicines.

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Dzugan, Jan. "Crack lengths calculation by unloading compliance technique for Charpy size specimens". Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-29077.

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The problems with the crack length determination by the unloading compliance method are well known for Charpy size specimens. The final crack lengths calculated for bent specimens do not fulfil ASTM 1820 accuracy requirements. Therefore some investigations have been performed to resolve this problem. In those studies it was considered that measured compliance should be corrected for various factors, but satisfying results were not attained. In the presented work the problem was attacked from the other side, the measured specimen compliance was taken as a correct value and what had to be adjusted was the calculation procedure. On the basis of experimentally obtained compliances of bent specimens and optically measured crack lengths the investigation was carried out. Finally, a calculation procedure enabling accurate crack length calculation up to 5mm of plastic deflection was developed. Applying the new procedure, out of investigated 238 measured crack lengths, more than 80% of the values fulfilled the ASTM 1820 accuracy requirements, while presently used procedure provided only about 30% of valid results. The newly proposed procedure can be also prospectively used in modified form for the specimens of different than Charpy size.

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Tilbrook, Matthew Thomas Materials Science &amp Engineering Faculty of Science UNSW. "Fatigue crack propagation in functionally graded materials". Awarded by:University of New South Wales. Materials Science & Engineering, 2005. http://handle.unsw.edu.au/1959.4/21885.

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Propagation of cracks in functionally graded materials (FGMs) under cyclic loading was investigated via experiments and finite element (FE) analysis. Alumina-epoxy composites with an interpenetrating-network structure and tailored spatial variation in composition were produced via a multi-step infiltration technique. Compressed polyurethane foam was infiltrated with alumina slip. After foam burn-out and sintering, epoxy was infiltrated into the porous alumina body. Non-graded specimens with a range of compositions were produced, and elastic properties and fatigue behaviour were characterised. An increase in crack propagation resistance under cyclic loading was quantified via a novel analytical approach. A simulation platform was developed with the commercial FE package ANSYS. Material gradient was applied via nodal temperature definitions. Stress intensity factors were calculated from nodal displacements near the crack-tip. Deflection criteria were compared and the local symmetry criterion provided the most accurate and efficient predictions. An automated mesh-redefinition algorithm enabled incremental simulation of crack propagation. Effects of gradient and crack-geometry parameters on crack-tip stresses were investigated, along with influences of crack-shape, crack-bridging, residual stresses and plasticity. The model provided predictions and data analysis for experimental specimens. Fatigue cracks in graded specimens deflected due to elastic property mismatch, concordant with FE predictions. In other FGMs, thermal or plastic properties may dominate deflection behaviour. Weaker step-interfaces influenced crack paths in some specimens; otherwise effects of toughness variation and gradient steps on crack path were negligible. Crack shape has an influence, but this is secondary to that of elastic gradient. Cracks in FGM specimens initially experienced increase in fatigue resistance with crack-extension followed by sudden decreases at step-interfaces. Bridging had a notable effect on crack propagation resistance but not on crack path. Similarly, crack paths did not differ between monotonic and cyclic loading, although crack-extension effects did. Recommendations for analysis and optimisation strategies for other FGM systems are given. Experimental characterization of FGMs is important, rather than relying on theoretical models. Opportunities for optimization of graded structures are limited by the properties of the constituent materials and resultant general crack deflection behaviour.

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Più fonti

Libri sul tema "R-curve"

Growth curve analysis and visualization using R. Boca Raton: CRC Press/Taylor & Francis Group, 2014.

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Orange, Thomas W. Estimating the R-Curve from residual strength data. [Cleveland, Ohio: National Aeronautics and Space Administration, Lewis Research Center, 1985.

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Orange, Thomas W. Method and models for R-Curve instability calculations. [Washington, DC]: National Aeronautics and Space Administration, 1988.

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Orange, Thomas W. Method and models for R-Curve instability calculations. [Washington, DC]: National Aeronautics and Space Administration, 1988.

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Orange, Thomas W. Method and models for R-Curve instability calculations. [Washington, DC]: National Aeronautics and Space Administration, 1988.

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Orange, Thomas W. Estimating the R-Curve from residual strength data. [Cleveland, Ohio: National Aeronautics and Space Administration, Lewis Research Center, 1985.

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Bradt, R. C. Fracture Mechanics of Ceramics: Composites, R-Curve Behavior, and Fatigue. Boston, MA: Springer US, 1992.

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Shah, Priti Kotak. Direct J-R curve analysis: Application to testing of nuclear structural materials. Mumbai: Bhabha Atomic Research Centre, 2004.

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International Symposium on the Fracture Mechanics of Ceramics (7th 1999 Moscow, Russia). Crack-microstructure interaction, R-curve behavior, environmental effects in fracture, and standardization. New York: Kluwer Academic/Plenum, 2002.

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Hiser, A. L. Tensile and J-R curve characterization of thermally aged cast stainless steels. Washington, DC: Division of Engineering, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1988.

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Capitoli di libri sul tema "R-curve"

Munz, Dietrich, e Theo Fett. "R-Curve Behaviour". In Ceramics, 53–75. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-58407-7_4.

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Steinbrech, Rolf W. "R-Curve Behavior of Ceramics". In Fracture Mechanics of Ceramics, 187–208. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3350-4_14.

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Sakai, M., e M. Inagaki. "R-Curve Behavior of Ceramic Materials". In Sintering ’87, 796–801. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-1373-8_134.

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McCabe, D. E. "COD Concepts in R-Curve Testing". In The Crack Tip Opening Displacement in Elastic-Plastic Fracture Mechanics, 81–113. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-82818-8_5.

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Lube, T. "A Knoop-Indentation Method for R-Curve Determination". In Fracture Mechanics of Ceramics, 447–56. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4757-4019-6_34.

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Machado e Costa, Francisco, e Ana Cristina Braga. "Adjusting ROC Curve for Covariates with AROC R Package". In Computational Science and Its Applications – ICCSA 2020, 185–98. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58808-3_15.

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Machado e Costa, Francisco, e Ana Cristina Braga. "Exploring Methodologies for ROC Curve Covariate Study with R". In Computational Science and Its Applications – ICCSA 2021, 563–76. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-86973-1_40.

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Baik, S., S. M. Lee e B. S. Min. "R-curve Behavior of PZT Ceramics near Morphotropic Phase Boundary". In Fracture Mechanics of Ceramics, 371–85. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3350-4_26.

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Barinov, Sergej M., e Vladimir Ya Shevchenko. "Universal R-curve of Crack Propagation Resistance in Ceramic Composites". In Fracture Mechanics of Ceramics, 209–17. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3350-4_15.

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Förderreuther, A., G. Thurn e F. Aldinger. "R-Curve Effect and Process Zone in Coarse Grained BaTiO3". In Fracture Mechanics of Ceramics, 243–53. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4757-4019-6_20.

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Atti di convegni sul tema "R-curve"

Aram, Zainab, e Seyed Kamaledin Setarehdan. "R-R interval simulation based on power spectrum curve fitting". In 2013 20th Iranian Conference on Biomedical Engineering (ICBME). IEEE, 2013. http://dx.doi.org/10.1109/icbme.2013.6782206.

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Hojo, Kiminobu, Kazutoshi Ohoto e Itaru Muroya. "J Resistance Curve Estimation of Inhomogeneous CT Specimen". In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22047.

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In order to obtain the fracture toughness curve of inhomogeneous CT specimens, a simplified J-R curve estimation method has been proposed. To verify the applicability of this method, the fracture toughness test and the finite element analysis has been conducted. In overmatching case (mismatch ratio M = 2.2), the conventional ASTM standard’s J-R curve exceeded the J-R curve from the FE analysis in the plane strain condition by over 20%. On the other hand, the simplified J-R curve was located between J-R curves from the FE analyses in plane strain and plane stress condition. In undermatching case (M = 0.5), experimental J-R curves with and without the inhomogeneity effect were almost same and the conventional standard is applicable.

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Tandon, Samarth, Ming Gao, Ravi Krishnamurthy, Richard Kania e Gabriela Rosca. "Estimating J-R Curve From CVN Upper Shelf Energy and its Application". In 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64618.

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Accuracy in predictions of burst pressures for cracks in pipelines has significant impact on the pipeline integrity management decisions. One of the fracture mechanics models used for failure pressure prediction is API 579 Level 3 FAD ductile tearing instability analysis that requires J-R curves, i.e., crack resistance curves, for the assessment. However, J-R curves are usually unavailable for most pipelines. To overcome this technical barrier, efforts have been made to estimate the J-R curve indirectly from commonly available toughness data, such as the Charpy V-notched Impact Energy CVN values, by correlating the upper-shelf CVN value (energy) to the ductile fracture resistance J-R curve. In this paper, the theoretical background and studies made by various researchers on this topic are reviewed. Attempts made by the present study to establish correlations between CVN and J-R curves for linepipe materials are then presented. Application of this CVN-JR correlation to API 579 Level 3 FAD tearing instability assessment for failure pressure predictions is demonstrated with examples. The accuracy of the correlation is analyzed and reported.

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Zhu, Xian-Kui, e Poh-Sang Lam. "Deformation Versus Modified J-Integral Resistance Curves for Ductile Materials". In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78729.

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The J-integral resistance curve (or J-R curve) has been widely used as material property in fracture mechanics methods for structural integrity assessment. ASTM E1820 provides the standard fracture toughness test methods to measure JIc and J-R curves. The conventional J-R curve utilizes the J-integral parameter proposed by Rice [1] based on the deformation theory of plasticity. Due to crack-tip constraint effect, J-R curves of a material depend on specimen size, geometry type and crack length. In order to obtain size-independent resistance curves, Ernst [11] introduced a modified J-integral or Jm to minimize the size dependence and to characterize the resistance curve for large crack extensions beyond the limitation of deformation J-R curves. In the late 1980s and in the early 1990s, different experimental results showed the modified Jm-R curves were still size-dependent and may even behave worse than the deformation J-R curves. However, to date, the Jm-R curves are still regarded as “size-independent” in fracture mechanics analysis. To clarify this, the present paper gives a brief historical review of ductile resistance curves in terms of deformation J-integral and the modified Jm-integral, and evaluates the size dependence using experimental results for various steels and specimens, including A285 carbon steel and SENB specimens. A suggestion how to use the resistance curves is made accordingly.

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Zhu, Xian-Kui, Sebastian Cravero e Claudio Ruggieri. "Determination of J-R Curve for X60 Pipeline Steel Using SENT Specimens and Normalization Method". In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-78089.

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The normalization method is adopted in this paper to determine J-R curves for X60 pipeline steel using single-edge notched tension (SENT) specimens. A resistance curve procedure associated with the normalization method is developed to estimate crack extension, calculate crack growth corrected J-integral and generate a J-R curve directly using load-displacement data from a single test on SENT specimens. Based on experimental data for a typical pin-loaded SENT specimen, J-R curve for X60 pipeline steel is obtained by the normalization method and the conventional elastic unloading compliance method. The results show that the normalization method is simple and cost-effective, and can obtain J-R curves equivalent to the unloading compliance method in use of SENT specimens.

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Yue, Hongda, Longfa Pan, Yuejing Bin e Ken Chen. "Optical density curve model for CD-R dye coating". In Optical Storage (ISOS 2002), a cura di Fuxi Gan e Zuoyi Li. SPIE, 2003. http://dx.doi.org/10.1117/12.510114.

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Villanueva, Nora M., Marta Sestelo, Javier Roca-Pardiñas, Theodore E. Simos, George Psihoyios, Ch Tsitouras e Zacharias Anastassi. "An R Package For Analyzing Factor-By-Curve Interactions". In NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2011: International Conference on Numerical Analysis and Applied Mathematics. AIP, 2011. http://dx.doi.org/10.1063/1.3636960.

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Zhu, Xian-Kui, Tom McGaughy, Fabian Orth e Jon Jennings. "Review of Low-Constraint Fracture Resistance Testing With SENT Specimens". In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-24281.

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Fracture resistance is an important material property and characterized by a J-integral resistance curve (J-R curve) or a crack-tip opening displacement (CTOD) resistance curve. ASTM standard specimens with deep cracks are subject to bending dominant forces, leading to high crack-tip constraint conditions and conservative fracture resistance curves. Actual cracks occurring in line pipes and welds are often shallow ones dominated by tensile forces, resulting in low constraint conditions. Shallow cracks have been shown to generate elevated fracture resistance curves in comparison to standard deep-crack results. To reduce the over-conservatism of standard resistance curves and to produce more realistic toughness properties to meet the needs of strain-based design approaches for pipelines, different procedures and technologies have been developed over the years to determine the low-constraint fracture resistance curves by use of the single edge-notched tension (SENT) specimens. This includes the multiple specimen method developed and standardized by DNV for J-R curve testing, the single specimen method developed by CanMet for J-R and CTOD-R curve testing, and the single-specimen method developed by ExxonMobil for CTOD-R curve testing. This paper delivers a technical review of existing fracture test methods using SENT specimens, and discusses the advantages and limitations of each method.

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Zhu, Xian-Kui, e Brian N. Leis. "Application of Constraint Corrected J-R Curves to Fracture Analysis of Pipelines". In ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71202.

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Fracture properties of API X80 pipeline steel have been developed using a set of single edge notched bend (SENB) and single edge notched tension (SENT) specimens with shallow and deep cracks to generate different crack-tip constraint levels. The test data show that the J-R curves for X80 pipeline steel are strongly constraint dependent. To facilitate transfer of the experimental J-R curves to those for actual cracked components, like flawed pipeline, constraint corrected J-R curves are developed. The two-parameter J-A2 formulation is adopted to quantify constraint effect on the crack-tip fields and the J-R curves. The constraint parameter A2 is extracted by matching the J-A2 solution with finite element results for a specific crack configuration. A constraint corrected J-R curve is then formulated as a function of the constraint parameter A2 and crack extension Δa. A general method and procedure to transfer the experimental J-R curves from laboratory to actual cracked components are proposed. Using the test data of J-R curves for the SENB specimens, a mathematical expression representing a family of the J-R curves is constructed for X80. It is shown that the predicted J-R curves developed in this paper match well with experimental data for both SENB and SENT specimens. To demonstrate its application in assessing flaw instability, a pipeline with an axial surface crack is considered. For a crack depth of 50% of the wall thickness, the predicted J-R curve is found to be higher than that for the SENB specimen with the same crack length to width ratio. From this predicted J-R curve and crack driving force obtained by finite element analysis, the failure pressures of the pipeline at the crack initiation and instability are determined and discussed.

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Olson, Richard, e Ben Thornton. "Semi-Closed-Form Displacement Equations for Calculating J-R Curves From Pipe Fracture Experiments". In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45571.

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The equations to generate a J-R curve from a four-point bend test on circumferentially cracked pipe have been known for many years. Given the experimental pipe load-displacement record and crack growth, the only impediment to routinely calculating pipe J-R curves is the requirement to know the non-cracked pipe elastic and plastic displacements. Traditionally, finite element analyses are used to find these displacements. This paper presents a semi-closed-form solution for the total (elastic plus plastic) non-cracked pipe displacements that eliminates the need to perform finite element analyses to calculate a pipe J-R curve. Using a Ramberg-Osgood nonlinear representation of the stress-strain curve and the assumption that plane sections remain plane, beam bending equations can be written to find nonlinear beam displacements for pipe bend geometries with a base metal crack. Building on this result, the solution is extended to the dissimilar metal weld (DMW) case with five nonlinear materials. The non-cracked pipe displacement solutions are presented as well as comparisons using these equations between compact tension specimen J-R toughness curves and J-R curves from pipe experiments.

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Rapporti di organizzazioni sul tema "R-curve"

Grutzik, Scott Joseph, Kevin Strong e Steve Xunhu Dai. Investigation of R-Curve Behavior in Glass Ceramic Materials. Office of Scientific and Technical Information (OSTI), settembre 2019. http://dx.doi.org/10.2172/1568986.

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Mangin, Christophe. R-Curve Behavior for Silicon Carbide Whisker Reinforced Aluminum Oxide Composites. Fort Belvoir, VA: Defense Technical Information Center, gennaio 1990. http://dx.doi.org/10.21236/ada233958.

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Clowers, Logan N., Alberto Esteban Linares e Xiang Chen. Technical Manual for Automated J-R Curve Analysis Program Based on the ASTM E1820-18 Normalization Method. Office of Scientific and Technical Information (OSTI), ottobre 2018. http://dx.doi.org/10.2172/1484983.

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Singh, J. P., C. Y. Chu, C. Murphy e D. Singh. Microstructure / mechanical-property relationships and R-curve behavior in Si{sub 3}N{sub 4}/Si{sub 3}N{sub 4}(w) composites. Office of Scientific and Technical Information (OSTI), giugno 1992. http://dx.doi.org/10.2172/10185016.

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Eason, E. D., e E. E. Nelson. Improved model for predicting J-R curves from charpy data: Final report. Office of Scientific and Technical Information (OSTI), aprile 1989. http://dx.doi.org/10.2172/6301451.

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