1,721,035 research outputs found
Crack propagation in porous hardening metals
No full textSteady-state and quasi-static rectilinear crack propagation is analyzed in porous elastoplastic solids obeying the Gurson yield condition and flow-law. Both plane strain and plane stress conditions are considered under Mode I and Mode II loading conditions. The asymptotic crack-tip fields are obtained with reference to the incremental small strain theory in the case of linear isotropic hardening behavior of the matrix material. The porosity of the material is assumed constant, therefore the elastoplastic constitutive operator results in being self-adjoint.Elastic unloading and plastic reloading on crack flanks are taken into account
Asymptotic solution for Mode III crack growth in J2-elasto-plasticity with mixed isotropic-kinematic strain hardening
No full textMode III fracture propagation is analyzed in a J2-flow theory elastoplastic material characterized by a mixed isotropic/kinematic law of hardening. The asymptotic stress, back stress and velocity fields are determined under small-strain, steady-state, fracture propagation conditions. The increase in the hardening anisotropy is shown to be connected with a decrease in the thickness of the elastic sector in the crack wake and with an increase of the strength of the singularity. A second order analytical solution for the crack fields is finally proposed for the limiting case of pure kinematic hardening. It is shown that the singular terms of this solution correspond to fully plastic fields (without any elastic unloading sector), which formally are identical to the leading order terms of a crack steadily propagating in an elastic medium with shear modulus equal to the plastic tangent modulus in shea
Response to: Comments on E. Radi, D. Bigoni and D. Capuani, Effects of pre-stress on crack-tip fields in elastic, incompressible solids [International Journal of Solids and Structures 39 (2002) 3971-3996]
No full textWe sincerely thank A.N. Guz for having brought to our attention his large contribution to the topic analyzed by us, of which we were obviously unaware [with the exception mentioned in our footnote (2)].As far as the initial observations made by A.N. Guz are concerned, we specify that our formulation pertains to small deformations superimposed upon arbitrary large, homogeneous initial deformation. The similarity of the localization patterns found by us to real experiments [see for instance Vasko, G.M., Leo,P.H. and Shield T.W., Prediction and observation of crack tip microstructure in shape memory CuAlNi single crystals, J. Mech. Phys. Solids 50 (2002) 1843–1867] points out the physical sense of our results
Steady crack-growth in elastic-plastic fluid-saturated porous media
No full textAn asymptotic solution is obtained for stress and pore pressure fields near the tip of a crack steadily propagating in an elastic-plastic fluid-saturated porous material displaying linear isotropic hardening. Quasi-static crack growth is considered under plane strain and Mode I loading conditions. In particular, the effective stress is assumed to obey the Drucker-Prager yield condition with associative or non-associative flow-rule and linear isotropic hardening is assumed. Both permeable and impermeable crack faces are considered. As for the problem of crack propagation in poroelastic media, the behavior is asymptotically drained at the crack-tip. Plastic dilatancy is observed to have a strong effect on the distribution and intensity of pore water pressure and to increase its flux towards the crack-tip
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Buckling of Structures Under Tensile Dead Loading
No full textPossibility of bifurcations for structures subjected to tensile loads are investigated.
Examples of such structures are shown.
Theoretical findings are succesfully compared to experimental results
Cones of localized shear strain in incompressible elasticity with prestress: Green's function and integral representations
No full textThe infinite-body three-dimensional Green’s function set (for incremental displacement and mean stress) is derived for the incremental deformation of a uniformly strained incompressible, nonlinear elastic body. Particular cases of the developed formulation are the Mooney–Rivlin elasticity and the J2-deformation theory of plasticity. These Green’s functions are used to develop a boundary integral equation framework, by introducing an ad hoc potential, which paves the way for a boundary element formulation of three-dimensional problems of incremental elasticity. Results are used to investigate the behaviour of a material deformed near the limit of ellipticity and to reveal patterns of shear failure. In fact, within the investigated three-dimensional framework, localized deformations emanating from a perturbation are shown to be organized in conical geometries rather than in planar bands, so that failure is predicted to develop through curved and thin surfaces of intense shearing, as can for instance be observed in the cup–cone rupture of ductile metal bars
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