TRAJECTORIES OF UNSTABLY GROWING CRACKS IN MIXED-MODE I-II LOADING OFMARBLE BEAMS

XEIDAKIS GS SAMARAS IS ZACHAROPOULOS DA PAPAKALIATAKIS GE

Gs. Xeidakis et al., TRAJECTORIES OF UNSTABLY GROWING CRACKS IN MIXED-MODE I-II LOADING OFMARBLE BEAMS, Rock mechanics and rock engineering, 30(1), 1997, pp. 19-33

15

INGLESE

Article

Geosciences, Interdisciplinary","Engineering, Civil

Rock mechanics and rock engineering → ACNP

0723-2632

30

1

1997

19 - 33

ISI

0723-2632(1997)30:1<19:TOUGCI>2.0.ZU;2-5

The knowledge of the stress field under which a crack in an engineerin g material or a rock is propagated and the trajectory it follows durin g its growth, is very important. In this paper the prediction of the c rack growth trajectory and its initial angle theta(c) under mixed mode I-II loading is studied experimentally in marble beams. The three poi nt bending test is used, together with the strain energy density theor y (SED) of Linear Elastic Fracture Mechanics (LEFM). Experimental resu lts are compared with theoretical predictions. The experimental result s showed that: marble behaved as a brittle material; crack propagation was unstable and its trajectory followed, mainly, the grain boundarie s; the prediction of the critical angle theta(c) and the first part of the trajectory, from the crack tip up to the point G, where a global minimum of the strain energy density is reached, can satisfactorily be made with the SED theory. Beyond point G, the initial stress field is different, and for application of the SED theory, the boundary condit ions need redefinition.