Parametric analyses on multiscale elastic behavior of 3D braided composites with pore defects

The manufacturing-induced pore defects are inevitable, and show detrimental effects on the mechanical behavior of 3D braided composites. In this paper, two different multiscale modeling methods of pore defects are established to investigate the void type on the elastic behavior of 3D braided composites. The multiscale elastic responses under various loading conditions are also discussed. The parametric analyses have been conducted including the void characteristics (i.e. void distribution and void content), and braiding features (i.e. fiber content and braiding angles). Also, a homogenization method has been proposed to simplify the calculation of effective constants considering pore defects. Results show that the void type and void distribution have negligible effects on the elastic properties of yarns and braided composites. Oppositely, the void content shows the decisive influences. The fiber distribution has limited effects on the elastic behavior of yarns, but the opposite conclusion has been obtained for the fiber content and braiding angles. The matrix, fibers, axial and braiding yarns show diverse load-bearing responses under various loadings across scales. The present multiscale homogenization scheme is effective to predict the effective elastic constants of 3D braided composites. This method can simplify the elastic analyses of 3D braided composites considering pore defects.