Optimal design and testing of laminated light-weight composite structures with local reinforcements considering strength constraints part I: Design

The paper reports on a strength improvement method based on the recently published Ghost-Layer concept by Schläpfer and Kress [1] for identifying local reinforcements to a composite structure which is simulated with the finite element method. A pseudo-strength function (PSF) unifies the failure indices of the laminate layers of each finite element and allows for semi-analytical calculation of sensitivities with respect to layer thickness changes. Local reinforcements are generated by assigning a thickness value to parts of the virtual Ghost-Layers based on the sensitivity information. The method, manufacturing of test specimens, and validation are presented. High strength increase can be achieved with small amounts of additional mass. Details of the measurement techniques are presented in part II of this paper.