Design of a novel bonded-SENB specimen for determining the pure modes and the mixed-mode cohesive fracture energies in brittle and quasi-brittle adhesives

Abstract

Integrating fracture and damage mechanics with numerical methods in commercial software is essential for predicting the failure of structural adhesive joints. These joints often face complex loading conditions and fracture in a mixed-mode (tensile/shear) manner. Understanding the fracture energy of the adhesive in all loading conditions is crucial and requires precise measurement methods. While various laboratory specimens with different shapes and loading configurations have been proposed to study cracking behavior and fracture energy under pure modes or mixed-mode loading, some have practical limitations. This research introduces a new test configuration, bonded-SENB, for measuring the full range of fracture energies in brittle and quasi-brittle adhesive joints. This specimen is easy to prepare and test. A data reduction scheme based on the contour integral framework in ABAQUS is employed to investigate the effects of crack length and loading span on the fracture parameters. The fracture envelopes from this specimen are compared with results from conventional methods like double-cantilever beam (DCB) and end-notched flexure (ENF) tests, yielding strong agreement with standard fracture energy measurements.