Experimental study on flexural fatigue behavior of glass fibers/epoxy hybrid composites with statistical analysis

Abstract

Flexural fatigue behaviors were investigated experimentally for unidirectional glass fiber (U)/random glass fiber (R)/epoxy hybrid composite laminates. Three different hybrid composites, i.e. [0.5R/U/U]S, [U/0.5R/U]S and [U/U/0.5R]S were fabricated using hand lay-up technique with 37% total fiber volume fraction ( VfT), unidirectional glass fiber relative volume fraction ( VfU/ VfT) = 0.8 and of 5.5 ± 0.2 mm thickness. Flexural fatigue tests were performed at zero mean stress. A 20% reduction of the flexural stiffness was taken as a failure criterion. The effects of layer stacking sequences on both initial stress–no. of cycles to failure relationships and the relative surface temperature increase of the mentioned composites were investigated. The specimen failure modes have been recorded and discussed. The S–N curves and fatigue safe workability areas for the fabricated hybrid composites have been constructed as design curves. Two-parameter Weibull distribution function was used to obtain the scatter in the experimental results and to construct the reliability graphs for the fabricated hybrid composites.