Failure behavior of an epoxy matrix under different kinds of static loading

The yield and fracture behavior of an unreinforced epoxy resin has been inv estigated. The parabolic Mohr failure criterion was applied to experimental results under different loading conditions. From a plain resin slab., spec imens for tensile, torsion and compression tests were manufactured and the failure behavior of the resin was tested and discussed in detail. The resul ts of the mechanical tests and a fractographic study of the fracture surfac es were correlated with the stress-state-dependent strength and fracture st ress of the epoxy resin. This plays an important role in fiber-reinforced c omposites because just after cooling to room temperature the resin matrix i s under a tri-axial residual stress state. From the mechanical properties o f the plain resin and by using the parabolic failure criterion it is possib le to explain the low strain to failure of unidirectional laminates under t ransverse tensile loading. (C) 2001 Elsevier Science Ltd. All rights reserv ed.