Numerical and experimental analyses of the structural behaviour of braided composite materials

This paper presents the results of numerical and experimental analyses for the prediction of the mechanical properties of triaxial braided composite materials. Numerical analyses were performed by the finite element method using a general purpose element library. The aim was to focus on the limits of this type of modelling in the prediction of moduli, as these an often of more interest in typical composite applications. A parallel experimental activity was developed to validate numerical results, but difficulties in performing tests and the inability of standard testing methods only allowed a partial validation. For this reason, in the determination of certain properties, numerical models proved to be of major importance. The material object of the investigations is characterized by an important presence of open cells to obtain very low structural weight; this fact makes the structural analysis complex because of the increase of stress concentration phenomena. For a correct interpretation of local stresses, non-linear analyses were performed, but convergence problems occurred.