Delamination resistance of fibre reinforced polymer (FRP) plate subjected to out-of-plane loading

Delamination resistance of fibre-reinforced polymer (FRP) was characterized directly from plates that were Subjected to out-of-plane loading. Plate specimens used in the study were designed to be mainly unidirectional (0 degrees), with a single layer containing fibre in the orthogonal direction (90 degrees) inserted at the mid-thickness. The test set-up followed the description given in ASTM D3763-02, but using indenter of large radius to minimize the indentation damage. The Study found that the out-of-plane loading on the top surface generated firstly a flexural splitting crack in the 0 degrees direction from the bottom half of the plate. The splitting crack facilitated the delamination growth, resulting in a peanut-shaped area in the interlaminar region underneath the 90 degrees layer. The delamination resistance was characterized using the rate of energy loss per unit area of delamination growth, of which the value was found to be consistent with that determined previously, using flexural tests on beam-type specimens.