Experimental determination of material parameters in Cuntze's Failure-Mode-Concept-based UD strength failure conditions

The paper deals with the experimental determination of material properties required as model parameters in Cuntze's invariant-based Failure-Mode-Concept, applied to transversely-isotropic UD materials. For the envisaged 3D strength failure conditions (criteria) of this material, 5 strengths and 2 friction values must be determined. So far, no concept for the determination of the physically necessary internal friction values has been agreed to. In this publication bi-axial ARCAN tests are performed to obtain the friction values from data points on the inter-fiber failure fracture curve. The initiation of inter fiber failure is identified through sudden strain changes, recorded with strain gauges and digital image correlation. Further, the strength values for one specific material (M21/T700GC) are determined. To obtain the necessary shear strength three different shear test setups are investigated: the ±45°-Tension, the IOSIPESCU and the ARCAN test. They are compared considering the smoothness quality of their stress field distribution. The presented methodology enables to determine the two internal friction values.