PSI - Issue 13

Ermioni D. Pasiou et al. / Procedia Structural Integrity 13 (2018) 2101–2108 E. D. Pasiou, S. K. Kourkoulis , M. G. Tsousi, Ch. F. Markides/ Structural Integrity Procedia 00 (2018) 000–000

2105

5

(a) (b) Fig. 2. (a) Detailed view of the ISRM loading device with a typical specimen with d=R o /2 and θ=45

ο . The loci used for post processing of the

DIC data are clearly visible; (b) An overview of the experimental set up. Preliminary analysis of the raw data provided by the DIC indicated that the out of plane displacements (i.e. these normal to the plane of the specimens) were almost negligible. Therefore, from here on attention is paid to the in-plane displacement components, i.e., along the loading axis (u y ) and normally to it (u x ). For the comparison between all classes of specimens to be possible, a relatively low load level was chosen equal to P c =2.5 kN, ensuring also that the material is in its linear portion. All figures and graphs from this point on refer to the specific load level. Typical distributions of the u x and u y components of the displacement field (in which both the rigid body displacement and rotation have been removed) are shown in Fig.3b, for the ring, and a “φ0_d12.50” and “φ90_d12.50” type specimen. It is clear that the displacement fields share some common qualitative characteristics for all cases. Indeed, the extreme values of u x (red and purple areas at the first column of Fig.3b, respectively) are developed normally to the loading axis approaching the boundary of the hole while the respective ones of u y are observed at the specimen-jaw interface.

10.0

Ring φ0_d6.25 φ0_d12.50 φ0_d25.00 φ90_d6.25 φ90_d12.50 φ90_d25.00

7.5

5.0

Load [kN]

2.5

0.0

0.0

0.5

1.0

1.5

2.0

Displacement [mm]

(a) (b) Fig. 3. (a) Typical load-displacement curves; (b) The displacement components along the x- and y-axis for the ring (first raw), the “φ0_d12.50” specimen (middle row) and “φ90_d12.50” specimen (last row). Rigid body motions have been removed.