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Glass/Vinylester composite laminates are comprehensively characterised to assess its impact response behaviour under moisture exposure in marine structures. An instrumented drop weight impact machine is utilised to determine the impact responses of dry and immersed specimens in normal, salted and sea water. The specimens, which had three different thicknesses, were subjected to water exposure for a very long period of over 20 months before tested in a low-velocity impact experiment. Water uptake was measured primarily to study the degradation profiles of GRP laminates after being permeated by water. Matrix dissolution and interfacial damage observed on the laminates after prolonged moisture exposure while the absorption behaviour was found typically non-Fickian. The weight of the composite plates firstly increased because of water diffusion up to month 15 and then decreased due to matrix degradation. The specimens with 3, 6 and 9 mm thickness exhibited maximum water absorption corresponding to 2.6%, 0.7% and 0.5% weight gain, respectively. In general, the results indicated that water uptake and impact properties were affected by thickness and less by water type. Impact properties of prolonged immersed specimens reduced remarkably, and intense failure modes detected almost in all cases. The least sensitive to impact damage were wet specimens with 9 mm thickness as they indicated similar maximum load and absorbed energy for different impact energies.

To obtain the flexural response and the load-carrying capacity of composite plates with delamination, an efficient closed-form analytical solution is presented. Layerwise Higher-order Shear Deformation Theory and Rayleigh-Ritz approximation technique are applied. Fracture analysis is used to obtain the load-carrying capacity and primary steps of delamination propagation. The results include continuous functions. Furthermore, a considerable experimental study has been performed with specimens of various geometries and delamination types. The experimental investigation includes the fabrication procedure, tension experiments to obtain material properties and three-point bending tests of the delaminated plates.

A Layerwise Higher Order Shear Deformation Theory is developed for plates containing rectangular embedded delaminations undergoing non negligible lateral deflections. The effects of different parameters of the composite laminate and delaminated area are investigated analytically under buckling load and the results are compared with the three dimensional finite element analysis. The results demonstrate the effects of different geometrical parameters of the delaminated area and thickness on the deflection of a composite laminate. Also the initiation of debonding in opening and sliding fracture modes is predicted using the developed formulation.

The effects of different boundary conditions on the composite laminate containing embedded and through-the-width delamination under bending load are investigated analytically based on a developed Layerwise Higher Order Shear Deformation Theory (LHSDT) and the results are compared with the three-dimensional Finite Element Method (FEM). Contact energy has been calculated. The results demonstrate the ability of the presented method of predicting the displacement fields of a composite laminate containing delamination and obtaining stress-strain curves in bending condition. Moreover, strain energy release rate can be achieved using the obtained displacements to evaluate the initiation of delamination propagation around the boundaries of the considered delaminated region. Furthermore, the failure of the laminate will be predicted using conventional theories such as Tsai-Wu.

The effects of different parameters of the composite laminate and delaminated area are investigated analytically under buckling load based on a developed Layerwise Higher Order Shear Deformation Theory and the results are compared with the three dimensional Finite Element Analysis. The results demonstrate the consequences of different geometrical parameters of the delaminated area, lay-up sequences and thickness of the laminate on the deflection of a composite plate containing through-the-width delamination.

The mechanical properties of a sandwich panel and its skin, which are the main components of a steel-composite balcony overhang, are compared before and after the failure of the large-scale hybrid joint specimen subjected to imposed shear and bending loads. For this purpose, unidirectional tensile and three-point bending tests are performed on the extracted specimens from the failed balconies. The results include load-deflection and stress-strain curves and tables containing the strength and elasticity modulus for all extracted specimens. Repeating the tensile and flexural tests regarding to ASTM standards and comparing the results with the initial values of properties, contributed to find that the core shear modulus and the flexural strength of the skin reduce remarkably.

An improved and efficient analytical solution is proposed to predict the behaviour and the ultimate strength of composite laminates containing delamination. For this purpose, a Layerwise Higher order Shear Deformation Theory based on polynomial shape functions using Rayleigh–Ritz approximation technique are utilized. The ultimate strength and initial stages of propagation of the delaminated zone are determined using fracture analysis. The results demonstrate continuous functions to calculate in-plane and out-of-plane displacements, rotations, strains, stresses, energy and load carrying capacity under in-plane compressive loading. Moreover, a significant experimental investigation has been carried out for specimens with cross-ply stacking sequence and various material properties, geometries, delamination type and boundary conditions. The experimental study includes fabrication process, tensile tests to determine material properties and buckling test of the defected specimens.