Fracture toughness of glasses as measured by the SCF and SEPB methods

The fracture toughness, K-IC, of six glasses was measured by the surface crack in flexure (SCF) and single edged precracked beam (SEPB) methods. Results depended upon the loading rate as well as the test environment. Environmentally-assisted slow crack growth affects the results for tests done in air. Dry nitrogen testing is preferred. Crack healing may be a severe complicating factor with precracked flexure bar type specimens if the specimens are unloaded between the precracking and final fracture test. Success in K-IC, testing depends to a large degree on upon the ability to make good precracks. (C) 2017 Elsevier Ltd. All rights reserved.