Fracture of Compressed Brittle Bodies with a Crack

Abstract

The fracture of brittle specimens with an initial crack under uniaxial compression is studied experimentally. The effect of the crack orientation on the fracture of the specimens is examined. It is established that the crack nucleates and advances mainly in the loading direction (longitudinal fracture being predominant). The brittle material is modeled taking into account the difference between the compressive and tensile strengths of the material, the accumulation of damage, and the degradation of strength. The results obtained with the model in analyzing the fracture of brittle specimens with an initial crack under uniaxial compression are in satisfactory agreement with experimental data Introduction. It is very difficult to analytically describe the stability of compressed brittle bodies with an initial crack because of the complexity and diversity of the associated processes. The analytic solutions found in (3-6, 15, 18) are based on some assumptions and in many cases inadequately describe the real fracture behavior of brittle bodies with cracks. The stability of brittle bodies with an initial crack is addressed in many experimental studies (2, 6, 16, 19). Some of them are concerned with the limiting state of a brittle solid under various types of loading, and some with the stability of thin glass or polymethylmethacrylate plates with an initial crack under tension. There are very few experimental studies of the stability of brittle bodies with an initial crack under uniaxial compression. This problem is of importance for studying the fracture of rocks. The reason why the problem has not been studied adequately is the difficulty of fabricating specimens so that they do not buckle under compression. Therefore, the numerical simulation of the fracture of solids and the analysis of the accompanying phenomena were performed in many studies. A considerable advance in this field was made in (11-14, 17, 20). In view of the above, we set out here to develop a procedure for preparing brittle specimens with an initial crack, to experimentally study the fracture of such specimens under uniaxial compression, and to develop a brittle material model that would provide as real as possible (being in best agreement with experimental observations) description of the fracture of loaded