Abstract:

The improvement of the testing technique for the measurement of the Mode I ductile crack propagation resistance
is reported. The test consists of a side-grooved Double Cantilever Beam (DCB) specimen being loaded via pins.
A necking zone model, with the necking zone (total width = dn ) present along both sides of the path of the
crack propagating under plane stress conditions, is used to model ductile crack propagating problems. The test
shows that the average strain in the necking zone is related only to the property of the material and the thickness
of the specimen. An engineering approach based on this model to calculating the crack propagation resistance is
derived. A series of experiments on mild steel was conducted to improve the design of the DCB specimens and to
examine the reliability of the necking zone model.

Key words: Ductile fracture, Cantilever beam, Specimens, Neck model, Mild steel