A T-stress controlled specimen for mixed mode fracture experiments on brittle materials

In this paper, the compact tension-shear (CTS) specimen is studied using three-dimensional finite element analysis. The values of T-stress are calculated for the complete range of mode mixities from pure mode I to pure mode II. The results show that the magnitude of T-stress is negligible for entire combinations of mode I and mode II when the crack length is about half of the CTS specimen width. Subsequently, an innovative approach is proposed by introducing some modifications in the CTS specimen for producing desired amplitudes of T-stress. It is shown that the new test specimen can provide a wide range of positive and negative T-stresses relative to the stress intensity factors KI and KII. The proposed specimen is very suitable for mixed mode fracture experiments on brittle materials, because three-parameter fracture criteria (based on KI, KII, and T) have been proven to be more accurate in estimating the mixed mode fracture resistance of engineering materials.

► The values of T-stress are calculated for the compact tension-shear specimen.
► An innovative approach is suggested for producing desired values of T-stress.
► A new test specimen is proposed which can provide a wide range of T-stresses.
► The specimen provides more accurate states of stress and strain near the crack tip.