stefano secchi | Consiglio Nazionale delle Ricerche (CNR) (original) (raw)

Papers by stefano secchi

Traditional phenomenological constitutive relationships sometimes fail in the description of mech... more Traditional phenomenological constitutive relationships sometimes fail in the description of mechanical behaviour of plain concrete. In such circumstances more refined models are necessary, which takes into account the multiphase structure of the material. This paper presents a generalised finite element formulation, which incorporates solid and fluid phases together with a temperature field. The model is developed to obtain time-dependent solutions of 2-D cases, such as concrete gravity dams subjected to loading-unloading cycles, non-homogeneous specimens subjected to thermo-mechanical effects, etc. A fully coupled cohesive-fracture discrete model, which includes thermal and hydraulic loads, is adopted to describe crack nucleation and propagation. The evolution of fractures leads to continuous topological changes of the domain and these are handled by systematic local remeshing of the domain and by a continuous change of fluid and thermal boundary conditions. In the adopted approac...

Bookmarks Related papers MentionsView impact

This paper presents a numerical procedure for cohesive hydraulic fracture propagation. The quasi ... more This paper presents a numerical procedure for cohesive hydraulic fracture propagation. The quasi static problem of crack nucleation and/or advancement is solved by successive remeshing when domain changes are originated and projections are required in a backward solution scheme. This projection is directly applied to residual nodal vectors (forces and fluxes) of the previous step. This vector is projected using the element shape functions of the old mesh, hence ensuring the fulfilment of the balance equations. The resulting procedure is simple, however checks have to be made on its capability of conserving the energy.

Bookmarks Related papers MentionsView impact

Wind and Structures, 2002

ABSTRACT

Bookmarks Related papers MentionsView impact

Icf11 Italy 2005, May 24, 2013

Bookmarks Related papers MentionsView impact

Lecture Notes in Applied and Computational Mechanics, 2012

Bookmarks Related papers MentionsView impact

$Research paper thumbnail of Hydraulic fracturing and its peculiarities$

Asia Pacific Journal on Computational Engineering, 2014

Bookmarks Related papers MentionsView impact

$Research paper thumbnail of Cohesive fracture in thermoelastic medium: a coupled analysis$

The paper presents a fully-coupled numerical model for the analysis of fracture initiation and pr... more The paper presents a fully-coupled numerical model for the analysis of fracture initiation and propagation in a two dimensional non-homogeneous elastic medium driven by a transient thermal field. Cohesive crack behaviour is assumed for the solid. The solution of the coupled problem is obtained using the finite element method. Evolution of the process zone results in continuous changes of the domain topology. This is accounted for by updating the boundary geometry and successive remeshing of the domain. Optimality of the shape of the finite elements generated is controlled and the mesh density is adjusted adaptively on the basis of an error indicator which is calculated using the solution at previous steps. A numerical test case is presented, which demonstrate the effectiveness of the proposed procedure.

Bookmarks Related papers MentionsView impact

IABSE Symposium, Seoul 2001: Cable-Supported Bridges - Challenging Technical Limits, 2001

... [3] DIANA G. and CHELI F., Dinamica e vibrazione dei sistemi meccanici, 2° Vol., UTET Libreri... more ... [3] DIANA G. and CHELI F., Dinamica e vibrazione dei sistemi meccanici, 2° Vol., UTET Libreria, Torino, 1993. ... 12, Ed. Pubblicemento, Rome, 1998. [9] MARQUES DA SILVA F. and SARAIVA JG, On the aerodynamic stability of the new Tagus bridge on Lisbon, Proc. ...

Bookmarks Related papers MentionsView impact

Journal of Materials Processing Technology, 1997

Bookmarks Related papers MentionsView impact

$Research paper thumbnail of A method for 3-D hydraulic fracturing simulation$

International Journal of Fracture, 2012

Bookmarks Related papers MentionsView impact

Poromechanics V, 2013

Simulation of 2D and 3D hydraulic fracturing in fully saturated porous media is presented. The di... more Simulation of 2D and 3D hydraulic fracturing in fully saturated porous media is presented. The discrete fracture/s is/are driven by the fluid pressure. A cohesive fracture model is adopted where in the 3D case the fracture follows the face of the element around the fracture tip which is closest to the normal direction of the maximum principal stress at the tip while in the 2D setting the fracture follows directly the direction normal to the maximum principal stress. No predetermined fracture path is needed. This requires continuous updating of the mesh around the crack tip to take into account the evolving geometry. The updating of the mesh is obtained by means of an efficient mesh generator based on Delaunay tessellation. The governing equations are written in the framework of porous media mechanics and are solved numerically in a fully coupled manner. Numerical examples dealing with well injection in a geological setting and hydraulic fracture in a concrete dam conclude the paper.

Bookmarks Related papers MentionsView impact

Frontiers of Architecture and Civil Engineering in China, 2011

Bookmarks Related papers MentionsView impact

ABSTRACT

Bookmarks Related papers MentionsView impact

$Research paper thumbnail of Mesh adaptation and transfer schemes for discrete fracture propagation in porous materials$

International Journal for Numerical and Analytical Methods in Geomechanics, 2007

This paper presents a numerical procedure for cohesive hydraulic fracture problems in a multiphas... more This paper presents a numerical procedure for cohesive hydraulic fracture problems in a multiphase system. The transient problem of crack nucleation and/or advancement, with the ensuing topological changes, is solved by successive remeshing and projection of the field variables required in the time marching scheme. The projection is directly applied to the nodal vector of the previous step and is performed by means of a suitable mapping operator which acts on nodal forces and fluxes. This hence ensures ‘a priori’ the local fulfilment of the balance equations (equilibrium and mass conservation). The resulting procedure is computationally simple; however checks have to be made on its capability of conserving strain energy of the system. The latter property together with the accuracy of the solution is heuristically assessed on the basis of numerical benchmarks. Copyright © 2007 John Wiley & Sons, Ltd.

Bookmarks Related papers MentionsView impact

$Research paper thumbnail of Cohesive fracture growth in a thermoelastic bimaterial medium$