Fracture study of rigid foam using single edge notched bend specimens with inclined notch

Abstract

This paper presents results from a study of fracture behavior of rigid foam. Various mixed-modes I/II loading conditions were generated by the aid of single edge notched three point bending (SENB) test specimens containing an inclined notch as an initial crack. Three-dimensional finite element models of the SENB specimens were developed for analyzing the fracture test data. From the experimentally measured crack growth initiation loads various mixed-mode I/II critical strain energy release rates were computed by the virtual crack closure technique. The analysis revealed that besides mode I and mode II, there was also insignificant mode III component of the critical strain energy release rate. The variation of the critical strain energy release rate mode components with increase of the notch inclination was studied. It was found that the relative amount of the mode II component progressively decreases with increasing the notch inclination. It was concluded that the considered version of the SENB test specimen can be used for investigating fracture behavior of rigid foams in a function of the mixed-mode ratio over an interval of 0 G a IIC /G a C 0.413. It was found also that the theory of Sih can be applied successfully for analysis of mixed-mode I/II fracture in rigid foams.