Through-the-thickness distribution of strains in laminated composite plates subjected to bending

In this paper, the through-the-thickness deformation of laminated composite plates subjected to out-of-plane line and concentrated loads is studied experimentally and numerically using different span to depth ratios. Experimental inspection of the specimens is carried out by combining two different techniques: embedded fibre Bragg grating sensors for internal strain measurements and surface-mounted resistive strain gauges for surface strain measurements at selected locations. To eliminate the contribution due to the strain concentration in the vicinity of the loading point and highlight that due to shear effects, measurements are carried out at various distances from the load application by displacing the specimens in the loading frame. A departure from linearity in the through-the-thickness strain distribution is highlighted for small span to depth values. Results are compared to numerically calculated values from finite-element simulations using both laminated-shell and solid elements.