prof. Schrefler's seminar at SISSA

[Emanuele Tuillier Illingworth]

MATHLAB SEMINAR ANNOUNCEMENT


Speaker: Prof. B.A. Schrefler (University of Padua - Department of 
Civil, Environmental and Structural Engineering)

Date: Tuesday, 23 September, 2014 - 16:00

Room: SISSA - Santorio A - room 137

Abstract: Fracture tip advancement and pressure distribution of fracture 
in 2D and 3D fully saturated porous media is investigated in detail 
because of their peculiar features [1, 2, 3]. A cohesive fracture model 
is adopted for this purpose together with a discrete crack and without 
predetermined fracture path. The Rankine criterion is used for fracture 
nucleation and advancement. The solution method is based on standard 
Finite Elements where in a 2D setting the fracture follows directly the 
direction normal to the maximum principal stress while in the 3D case 
the fracture follows the face of the element around the fracture tip 
closest to the normal direction of the maximum principal stress at the 
tip. This procedure requires continuous updating of the mesh around the 
crack tip to take into account the evolving geometry. The updated mesh 
is obtained by means of an efficient mesh generator based on Delaunay 
tessellation [4, 5]. Some comparison is made with the XFEM method. The 
governing equations for both approaches are written in the framework of 
porous media mechanics and are solved numerically in a fully coupled 
manner. Numerical examples dealing with well injection (constant inflow) 
in a geological setting, hydraulic fracture in 2D and 3D concrete dams 
(increasing pressure) and a peeling test for a fully saturated porous 
medium are shown and stepwise tip advancement and pressure oscillations 
are evidenced.

REFERENCES
[1] F. Tzschichholz, H.J. Herrmann, Simulations of pressure fluctuations 
and acoustic emission in hydraulic fracturing. Physical Review E, Vol. 
5, pp 1961-1970, 1995.
[2] B.A. Schrefler, S. Secchi, L. Simoni, On adaptive refinement 
techniques in multifield problems including cohesive fracture. Comp 
Methods Appl Mech Engrg, Vol. 195, pp 444-461, 2006.
[3] F. Pizzocolo, J.M. Hyughe, K. Ito, Mode I crack propagation in 
hydrogels is stepwise. Engineering Fracture Mechanics, Vol. 97, pp 
72-79, 2013.
[4] S. Secchi, L. Simoni, An improved procedure for 2-D unstructured 
Delaunay mesh generation. Advances in Engineering Software, Vol. 34, pp 
217-234, 2003.
[5] S. Secchi, B.A. Schrefler, A method for 3-D hydraulic fracturing 
simulation. Int J Fracture, Vol. 178, pp 245-258, 2012.