Mode I fracture testing of pultruded glass fiber reinforced epoxy rods: Test development and influence of precracking method and manufacturing

Pultruded glass fiber polymer-matrix composite rods are industrially produced for various applications. The development of a quasi-static mode I delamination test for these rods using a modified Double Cantilever Beam specimen is described. Issues for investigation were size and shape of test specimens, type of load introduction, and different pre-cracking methods. When the test procedure was applied to rods with different lengths, a dependence of the R-curve behavior on the specimen length was revealed. This is attributed to the strong fiber bridging that was observed in the tests. There are also indications for manufacturing effects on scatter.