Abstract

In this work, 3D printing (3DP) technology is applied to study rock fracturing behaviors in Brazilian disc tests. First, uniaxial compression tests were performed to identify the most suitable 3DP material from five available 3DP materials, i.e., ceramics, gypsum, PMMA (poly methyl methacrylate), SR20 (Acrylic copolymer) and resin (accura® 60), to simulate hard and brittle rocks. The experimental results demonstrated that the transparent resin produced via Stereolithography (SLA) was the best 3DP material for mimicking rocks. Then, static and dynamic Brazilian disc tests were carried out on the resin-based 3DP rocks and the corresponding prototype rocks. The testing results show that the fracturing behaviours of the 3DP rocks agreed well with those of the prototype rocks, which confirms the feasibility and validity of using 3DP to study rock fracturing behaviors in tensile tests. This work facilitates the application of 3DP to rock mechanics.

1. Introduction

Rock fracturing has been traditionally studied in the laboratory using natural rocks. However, at present, the experimental study of rocks is encumbered by three problems:

  1. rocks are both heterogeneous and unrepeatable;

  2. rock cores collected from deep underground are difficult and expensive; and

  3. manmade rock specimens with internal structures are difficult to fabricate. To solve these problems, identifying and developing some alternative materials and techniques are needed.

Three-dimensional printing (3DP), also called additive manufacturing, may help to address the rock sample preparation problem. 3DP has advantages over conventional manufacturing in fast and flexible preparation, high repeatability, and preparation of complex internal defects [1]. Due to these benefits, 3DP has been widely applied in biomedicine [2] and materials science [3] etc.

However, the application of 3DP in rock mechanics is in its infancy. By combination of the CT scan, 3D reconstruction and 3DP technologies, Ju et al. [4] produced a physical model to replicate natural coal rock. Jiang and Zhao [5] produced 3DP samples with polylactic acid (PLA) using fused deposition manufacturing (FDM) technique. Fereshtenejad and Song [6] studied the means of enhancing the compressive strength of the 3D printed gypsum samples. However, in these studies, the 3DP samples failed/yielded with low compressive strength, i.e., between 1 to 30 MPa, exhibiting ductile behavior. Therefore, a more brittle and strengthened 3DP material should be used to effectively mimic hard and brittle rocks.

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