Draping Behavior of Carbon Non-Crimp Fabrics and Its Effects on Mechanical Performance of the Hemispherical Composites

In order to investigate the draping behavior of non-crimp fabrics（NCFs）, two types of carbon NCFs with tricot-chain stitches or chain stitches were formed on a hemispherical mould via a stretch forming process. The shear angle and forming defects of the fabrics were measured on the hemisphere, under different blank holder forces（BHFs）. The results showed that increasing BHF could enhance the shear angle slightly, reduce the asymmetry for the deformation of the fabrics, and change the main type of the process-induced defects. Besides, compression tests were performed on the corresponding composite components. By analyzing the change of fiber volume fraction and structural parameters of the textile reinforcements, the effects of draping behavior of NCFs on the mechanical performance of the composites were studied. The results reveal that draping process has distinguishable impacts on the mechanical properties of the final components, which is closely related to the stitching pattern of the NCFs.

Analytical Solution for Predicting In-plane Elastic Shear Properties of 2D Orthogonal PWF Composites

This paper proposes a new analytical solution to predict the shear modulus of a two-dimensional（2D） plain weave fabric（PWF） composite accounting for the interaction of orthogonal interlacing strands with coupled shear deformation modes including not only relative bending but also torsion,etc.The two orthogonal yarns in a micromechanical unit cell are idealized as curved beams with a path depicted by using sinusoidal shape functions.The internal forces and macroscopic deformations carried by the yarn families,together with macroscopic shear modulus of PWFs are derived by means of a strain energy approach founded on micromechanics.Three sets of experimental data pertinent to three kinds of 2D orthogonal PWF composites have been implemented to validate the new model.The calculations from the new model are also compared with those by using two models in the earlier literature.It is shown that the experimental results correlate well with predictions from the new model.

Fractography and morphology of shear bands of a Zr-based bulk metallic glass

Bulk metallic glasses（BMGs）have attracted considerable attention in the last few decades particularly triggered by their potential applications as novel structural and/or functional materials,owing to their superior strength,large elastic strain limit and relatively low Young′s modulus etc.compared to their crystalline counterparts.Here,a 3Dreconstruction application to the fractography and the morphology of shear bands was reported for a ductile Zr_（56）Co_（28）Al_（16）（at.%）BMG through a Phenom series desktop scanning electron microscope.The results of the 3Dreconstruction and the following contour analysis indicate a typical shear fracture mode for the investigated alloy.It is inferred that the fractography and the morphology of shear bands might be dependent on their composition,structure states,and loading conditions for BMGs.