A novel method to extract the fracture resistance by analysis of the 3D displacement field around a propagating crack has been applied to irradiated nuclear graphite. The ability to test small specimens is essential for irradiated materials, due to both safety and limited availability of material.
The usual analytical expressions that might be used to obtain fracture toughness are shown to be inaccurate in these specimens. The new method, which applies synchrotron tomography, digital volume correlation and finite element analysis, provides reliable data, and demonstrates R-curve behaviour in radiolytic oxidised nuclear graphite (ie rising toughness with crack propogation) due to the interaction of the crack with the porous microstructure.
Read the paper in full in Carbon.