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

摘要

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 (V_(fT)), unidirectional glass fiber relative volume fraction (V_(fU)/V_(fT)) = 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.