Elastic properties of 3D-printed physical models: Fluid substitution observations in cracked media
Long Huang, Nikolay I. Dyaur, Robert R. Stewart · 2015
Summary New 3D printing techniques using different materials and structures, provide opportunities to understand porous or fractured materials and fluid effects on their elastic properties. We use a 3D printer (Stratasys Dimension SST 768) to print one 'solid' cube model and another cube model with penny-shaped cracks. The printing material is ABS thermoplastic with a density of 1.04 g/cc, a P-wave velocity of 2179 m/s and a shear-wave velocity of 887 m/s. The solid cube has porosity of about 4%. We use ultrasonic transducers (500 kHz) to measure both P- and shear-wave velocities. P-wave velocity of the solid cube ranges from 1941 to 1952 m/s in the bedding plane. The velocity of the fast shear-wave traveling in the bedding plane ranges from 898 m/s to 901 m/s and the slow shear-wave velocity ranges from 849 m/s to 853 m/s. In the direction normal to bedding plane, the P-wave velocity is about 1835 m/s and shear-waves ranges from 839 m/s to 843m/s. The cracked model, gives a density of 0.79 g/cc and a porosity of about 24%. This model is closer to VTI symmetry with a P-wave velocity of 1438 m/s parallel to symmetry direction and 1638 m/s in the bedding plane. The fast and slow S-wave velocities are 825 m/s and 665 m/s respectively. Q factors for P- and S-waves in different directions are also estimated using spectral ratio method and we observe QP ranges from 14.9 to 16.7 and QS ranges from 23.8 to 29.9 assuming a VTI symmetry. A fluid substitution experiment is performed and an increase (26% to 38%) in P-wave velocities and a decrease (4% to 10%) in S-wave velocities are observed. 3D printed material has promising properties for seismic physical modeling which may vary depending on goal of scientific research.