Evolving discontinuities and cohesive fracture

Multi-scale methods provide a new paradigm in many branches of sciences, including applied mechanics. However, at lower scales continuum mechanics can become less applicable, and more phenomena enter which involve discon- tinuities. The two main approaches to the modelling of discontinuities are briefly reviewed, followed by an in-depth discussion of cohesive models for fracture. In this discussion emphasis is put on a novel approach to incorporate triaxi- ality into cohesive-zone models, which enables for instance the modelling of crazing in polymers, or of splitting cracks in shear-critical concrete beams. This is followed by a discussion on the representation of cohesive crack models in a continuum format, where phase-field models seem promising

JGraphT -- A Java library for graph data structures and algorithms

Mathematical software and graph-theoretical algorithmic packages to efficiently model, analyze and query graphs are crucial in an era where large-scale spatial, societal and economic network data are abundantly available. One such package is JGraphT, a programming library which contains very efficient and generic graph data-structures along with a large collection of state-of-the-art algorithms. The library is written in Java with stability, interoperability and performance in mind. A distinctive feature of this library is the ability to model vertices and edges as arbitrary objects, thereby permitting natural representations of many common networks including transportation, social and biological networks. Besides classic graph algorithms such as shortest-paths and spanning-tree algorithms, the library contains numerous advanced algorithms: graph and subgraph isomorphism; matching and flow problems; approximation algorithms for NP-hard problems such as independent set and TSP; and several more exotic algorithms such as Berge graph detection. Due to its versatility and generic design, JGraphT is currently used in large-scale commercial, non-commercial and academic research projects. In this work we describe in detail the design and underlying structure of the library, and discuss its most important features and algorithms. A computational study is conducted to evaluate the performance of JGraphT versus a number of similar libraries. Experiments on a large number of graphs over a variety of popular algorithms show that JGraphT is highly competitive with other established libraries such as NetworkX or the BGL.Comment: Major Revisio

Influence of the internal yarn nesting (shifting) on the local structural response of a satin weave composite: an experimental and numerical overview

The current paper emphasizes on the effect of internal yarn nesting (shifting) on the local structural response, such as, local stress - strain and the local damage of a satin weave composite. Detailed study of the variation of the local stress – strain behavior in the plies of a satin weave composite leads to the following conclusions: 1) local longitudinal strain in the plies of a satin weave composite is not influenced by the internal yarn nesting of the adjacent plies (position of the ply in the laminate); 2) local transverse stress as well as the weft yarn transverse damage is sensitive to the position of the ply in the laminate

Determination of the magnetic penetration depth in a superconducting Pb film

Under the terms of the Creative Commons Attribution (CC BY) license to their work.By means of scanning Hall probe microscopy technique, we accurately map the magnetic field pattern produced by Meissner screening currents in a thin superconducting Pb stripe. The obtained field profile allows us to quantitatively estimate the Pearl length ¿ without the need of pre-calibrating the Hall sensor. This fact contrasts with the information acquired through the spatial field dependence of an individual flux quantum where the scanning height and the magnetic penetration depth combine in a single inseparable parameter. The derived London penetration depth λL coincides with the values previously reported for bulk Pb once the kinetic suppression of the order parameter is properly taken into account.This work was partially supported by the Fonds de la Recherche Scientique-FNRS, the Methusalem Funding of the Flemish Government, the Fund for Scientic Research-Flanders (FWO-Vlaanderen), and the ARC Grant 13/18-08 for Concerted Research Actions, financed by the Wallonia-Brussels Federation. J.B. acknowledges support from FRS-FNRS (Research Fellowship). J.V.d.V. acknowledges support from FWO-Vl. The work of A.V.S. was partially supported by “Crédit de demurrage,” U.Lg.Peer Reviewe