Computer Design of a Controlled Fracture Test

This paper describes a new method of fracture toughness testing devised specifically to determine the crack growth resistance curves of brittle materials. With the aid of computer modelling, using a finite element program, a suitable test-piece shape and loading arrangement were predicted. Using this, stable cracks were propagated under increasing load in graphite test-pieces. The graphite was found to have an increasing resistance to crack growth as the crack propagated. The results compared favourably with those obtained in three point bending. The simple geometry of the arrangement provided a quick, inexpensive, but effective method of obtaining more nearly complete fracture toughness data without the need for a stiff testing machine and loading apparatus.