A novel direct tension-based loading framework for accurate Mode I fracture toughness determination in brittle geomaterials

This study investigates the tensile fracture toughness (Mode I) and crack propagation mechanisms in brittle geomaterials by introducing and validating a novel experimental-numerical framework. The core novelty of this research lies in the development of a unique direct tensile testing configuration for Edge Notched Cubic Samples (ENCS), where an external compressive force is internally converted into a pure tensile field. To ensure the reliability of this proposed method, results were systematically validated against Notched Brazilian Disc (NBD) tests and comprehensive numerical simulations using Abaqus. Unlike conventional methods, this integrated ENCS–NBD approach provides a more controlled environment for analyzing stress distribution and crack initiation. Findings indicate that ENCS specimens exhibited reduced fracture toughness values, which can be attributed to the more uniform distribution of pure tensile stress on the fracture surface compared to traditional indirect methods. The high degree of correlation between the experimental fracture patterns and numerical outcomes highlights the effectiveness of the proposed conversion-based tensile loading. This study concludes that the integrated methodology offers a superior and more accurate alternative for determining Mode I fracture toughness and understanding crack propagation in brittle geomaterials.