Arbitrary bi-dimensional finite strain crack propagation

In the past two decades numerous numerical procedures for crack propagation have been developed. Lately, enrichment methods (either local, such as SDA or global, such as XFEM) have been applied with success to simple problems, typically involving some intersections. For arbitrary finite strain propagation, numerous difficulties are encountered: modeling of intersection and coalescence, step size dependence and the presence of distorted finite elements. In order to overcome these difficulties, an approach fully capable of dealing with multiple advancing cracks and self-contact is presented (see Fig.1). This approach makes use of a coupled Arbitrary Lagrangian-Eulerian method (ALE) and local tip remeshing. This is substantially less costly than a full remeshing while retaining its full versatility. Compared to full remeshing, angle measures and crack paths are superior. A consistent continuationbased linear control is used to force the critical tip to be exactly critical, while moving around the candidate set. The critical crack front is identified and propagated when one of the following criteria reaches a material limiting value: (i) the stress intensity factor; or (ii) the element-ahead tip stress. These are the control equations. The ability to solve crack intersection and coalescence problems is shown. Additionally, the independence from crack tip and step size and the absence of blade and dagger-shaped finite elements is observed. Classic benchmarks are computed leading to excellent crack path and load-deflection results, where convergence rate is quadratic

An embedded formulation with conforming

Use of strong discontinuities with satisfaction of compatibilit

Mixed-mode fracture and load misalignment on the assessment of FRP-concrete bond connections

Considerable dispersion is usually found in experimental data concerning the material properties of FRP-concrete bond connections. In pure shear models, the direction of FRP loading is assumed to be parallel to the axis of the concrete specimen. However, in practice, it is very difficult to prevent load misalignment. This fact can have important consequences on the derivation of material properties from experimental data. This is why a parametric study is herein undertaken to thoroughly identify the role of the load misalignment in the behaviour of the connection. It is concluded that the load capacity of the connection significantly decreases in the case of a misaligned load pointing outwards the reinforced surface. It is also found that this effect is less relevant for thick laminates when compared to thin FRP sheets.Australian Research Council Discovery Early Career Researcher Award (DE150101703); Faculty of Engineering & Information Technologie

Modelling the behaviour of steel fibre reinforced concrete using a discrete strong discontinuity approach

The use of Fibre Reinforced Concrete (FRC) is gradually wide-spreading due to the significant advantages relatively to Normal Concrete (NC). In the case of steel fibres, the quasi-brittle behaviour of plain concrete structures can be modified into an enhanced ductile behaviour as a direct result of this addition. Since the mechanical properties of both FRC and NC can be significantly different, this work aims at developing a finite element formulation to specifically address the simulation of the behaviour of FRC members up to failure. For this purpose, the Conforming Generalised Strong Discontinuity Approach (CGSDA) is adopted with steel fibres explicitly introduced in the finite element mesh. The resulting formulation has the following main characteristics: i) variational consistency; ii) fibre elements automatically considered regardless of the presence of cracks; and iii) no additional degrees of freedom are required. The proposed formulation is validated using experimental results from tests conducted with different dosages of steel fibres.FCOMP-01-0124-FEDER-020275, FCT PTDC/ECM/119214/2010, FCT SFRH/BD/85922/2012, ARC DE150101703

A discrete strong discontinuity approach

http://www.sciencedirect.com/science/article/B6V2R-4VGX7RY-1/2/08a2ca3ad849c1cb32c40baa9e5ca1f