Fracture behavior of HT-90 structural foam – A three-dimensional analysis

The present work is concerned with the problem of the static fracture behavior of HT-90 rigid foam. Compact tension (CT) specimens were tested under displacement control in a laboratory environment, using a constant crosshead speed of 2 mm/min. The crack propagated along the direction of the initial crack. Loads and displacements were recorded automatically. A traveling microscope was used to measure the crack extension during the testing. A three-dimensional linear-elastic finite element model was developed in order to analyze the CT fracture test data. The model was verified through comparisons between simulated and measured load–displacement behavior of the CT specimen. The critical strain energy release rate was calculated using the virtual crack closure technique. The results obtained were conformed using the crack closure technique. The finite element analysis showed that the strain energy release rate is distributed non-uniformly along the crack front with maximum at the centre of the crack front. The critical stress intensity factor distribution was also analyzed. Three-dimensional model results were compared with results obtained using a modified three-dimensional model of the CT specimen with enforced plane strain boundary conditions. It was shown that the three-dimensional model represents a more accurate tool for analysis of the mode I static fracture behavior of the foam considered.