Characterising mode I/mode II fatigue delamination growth in unidirectional fibre reinforced polymer laminates

Abstract

In this paper, fatigue life estimation for delamination growth of laminated fibre reinforced polymer (FRP) composite structures in mode I and mode II based on fracture mechanics is presented. The proposed method was applied to delamination of glass/epoxy laminated composite. Both the threshold energy release rate ( ) and the delamination propagation based on Paris' law were studied. The double cantilever beam (DCB) specimen for mode I and 3 points End-Notched Flexure (3ENF) specimen for mode II were used for monotonic fracture tests and the resistance and as a function of delamination length were determined. For DCB tests, the fatigue onset life test was conducted and the threshold energy release rate, , was found for the subcritical region. Constant amplitude, displacement controlled cyclic fatigue test for both modes was conducted and the delamination crack growth rate ( ) as a function of maximum cyclic energy release rate and for DCB and 3ENF specimens were determined, respectively. From curve fitting to the experimental data, the Paris' law material constants C and m for mode I and mode II were obtained. Finally, the SEM fractography studies of delaminated surfaces of 3ENF static and fatigued specimens have been done and the different features observed on these surfaces were discussed.

Experimental Studies of Stiffness Degradation and Dissipated Energy in Glass Fibre Reinforced Polymer Composite under Fatigue Loading

“…Delamination is a serious detriment to the stiffness and compressive load carrying capability of a FRP composite laminate [3,4] and this area has been investigated for new advanced nanomaterial to enhance the fracture toughness of FRP materials [5]. Manjunatha et al [6] studied the stress-controlled constant amplitude tensile fatigue tests at stress ratio R=0.1 on rubber modified GFRP composites.…”

Onset-of-growth behavior of mode II delamination in a carbon fiber composite under spectrum fatigue loads

“…The predicted results are non-conservative and also there is difference compared to experimental values. The delamination studies under static and fatigue loads have been shown to exhibit some significant scatter in test results [3,8,11,12]. The constant amplitude data shown in Fig.…”

“…Hojo et al [9,10] studied the effect of Z-direction stitching on the fatigue behavior of CFRP under mode I delamination and showed that up to 5 times higher fatigue threshold could be obtained by stitching. The mode I delamination growth under fatigue loading was investigated by several others [3,11,12] to characterize the growth behavior.…”

A study of the mechanism of delamination fracture in bainitic magnetic yoke steel

“…Lucchini et al [15] studied the delamination mechanism of metal/polymer electrical interconnects with S-shaped planar meanders. Al-Khudairi et al [16] characterized the mode I and mode II delamination fatigue delamination growth in laminated fibre reinforced polymer (FRP) composite structures.…”