An EXtended Finite Element Model (XFEM) for Predicting Crack Propagation within Infrastructure Materials

Thursday, Jan. 12
Time: 4-5 p.m.
Location: Dow 642

Public is welcome

Presenter: Kenny Ng, Ph.D. candidate, Department of Civil and Environmental Engineering, (Adviser: Dr. Qingli Dai).

Abstract: The object of this study is to employ XFEM and image analysis techniques to numerically investigate crack propagation within infrastructure materials. The XFEM has been recently developed to eliminate remeshing by allowing crack propagation within continuous elements. The discontinuous crack and inclusion enrichment functions with level set method (LSM) were addressed in the XFEM. The crack growth angle and stress intensity factors (SIFs) were also formulated to predict the crack growth direction. The XFEM was developed with MATLAB program for predicting micro-crack behavior with Compact Tension (CT), single-edge notched beam (SEB) and indirect tension (IDT) tests. The developed XFEM was firstly validated with CT and SEB tests on a homogeneous sample. In order to capture the real material microstructure, the digital samples were generated with imaging processing and ellipse fitting techniques. The predicted crack propagation with XFEM simulation on digital samples was compared with fracture pattern of lab-tested SEB and IDT specimens. The comparison results on open-mode middle-notched and mixed-mode offset-notched SEB and IDT tests indicate the developed XFEM has the ability to accurately predict fracture behavior within heterogeneous infrastructure materials. In addition, the internal frost-induced damage within an idealized pore system was also analyzed and simulated using XFEM.

Lautala member of site visit committee

Pasi Lautala, research assistant professor (CEE) and director of the Rail Transportation Program (RTP), a part of the Michigan Tech Transportation Institute (MTTI), was a member of a site visit committee of the Natural Sciences and Engineering Research Council of Canada. The committee evaluated the University of Alberta’s proposal to establish an industrial research chair in railway geomechanics. Lautala’s recent visit took him to Edmonton.