MIFACRIT aimed at developing a failure criterion for fiber reinforced polymer (FRP) structures. This criterion allowed reliability and lifetime assessments of structural parts and systems made of several stack configurations. It shall be deduced from mechanical effects within the microstructure of the FRP structures in order to cover various mechanical loading situations. This ambitious goal was approached by a symbiotic combination of experimental test and analysis work with in-depth assessment and evaluation based on numerical simulation applying fracture / damage mechanics concepts. The material tests comprised visco-elastic characterisation and stress tests applying constant strain rate and cyclic loads, respectively. The tests were performed at different temperatures and frequencies. Most importantly, they included a variety of loading situations such as tensile and bending loads but also combinations of normal and shear components.

The analysis determined the visco-elastic material properties and the micro-structural effects responsible for damage and failure of the FRP structure in a comprehensive way. The in-depth analysis of the damage and failure effects by means of numerical simulation applied a two stage (global / local) sub-modelling strategy. The essential model parameters were calibrated by measured data and the simulation results were verified by the experimental findings. Combining experiment and simulation this way, the common link between the failure effects caused by the various loading situations were shown and explained by means of an objective mechanical criterion, which was identified and validated throughout the MIFRACRIT project. In addition, threshold quantities were determined for the criterion found to ultimately provide the means for precise lifetime predictions based on this physics of the failure approach.