Micromechanical transverse tensile crack propagation of unidirectional fiber reinforced epoxy SMC slice imbedded in a TDCB specimen

A mode-I type of crack propagation and branching on account of fracture energy failure mechanisms methodology is investigated in unidirectional (UD) fiber reinforced epoxy sheet molding compounds (SMC). In order to eliminate the influence of structural boundary conditions with various crack lengths on tip K (stress intensity factor) value to a greatest extent, a tapered double cantilever beam (TDCB) tensile sample is selected as the far-field boundary, the SMC slices with pre-cracks are embedded into TDCB samples, which are referred to as the embedded TDCB (E-TDCB) geometries. By applying the transvers tensile load to E-TDCB, embedded SMC is provided with far-field driving force for crack propagation, so as to obtained a great agreement between stable crack propagation and minor tip K oscillation. Both E-TDCB and dummy TDCB (d-TDCB) samples were selected for experimental test with comparation. The dynamic crack propagation parameters (work components of far-field driving force as well as crack length and Crack tip open displacement et al.) were measured and analyzed with progressive damage criterion. Although in disparate principle, the numerical prediction with proposed constitutive law correlates well with experimental results.