Mixed-mode I/II fracture behavior for adhesively-bonded pultruded GFRP joint under four-point bending

Abstract

The experimental investigation of mixed-mode I/II fracture behavior for the adhesively-bonded pultruded GFRP joint was performed with the four-point single leg bending (4SLB) test. Cracks initiated and propagated in mat layer of the pultruded GFRP laminate for 4SLB specimens with three different thicknesses of upper adherend. The compliances of 4SLB specimens were experimentally and numerically determined. The extended global method was used for providing the simple closed-form solutions of the mixed-mode I/II fracture toughness in initiation and propagation stages, which was compared with the obtained results using virtual crack closure technique (VCCT). Combined with the pure mode-I and mode-II fracture toughness determined by using double cantilever beam (DCB) test, four-point end-notched flexure (4ENF) test, respectively, the mixed-mode fracture criteria of adhesively-bonded pultruded GFRP joint were constructed. Then, the load–displacement curves of 4SLB specimens obtained by VCCT were compared to experimental results for validating the accuracy and applicability of the developed fracture criteria of adhesive GFRP joint.