Longitudinal deformation of fibre reinforced metals: influence of fibre distribution on stiffness and flow stress

Abstract

A computational analysis of the longitudinal deformation of continuous fibre reinforced metals is presented. Elastic and elastic-plastic matrix behaviour are considered. Analytical approaches are confronted with finite element analyses (FEA) for varying fibre distributions, ranging from single fibre unit cells to complex cells. Analysis of microfields shows that the main cause for deviation from the equistrain rule of mixtures is a stiffening effect of matrix confinement when surrounded by touching fibres arranged as ''rings''. Comparison with FEA shows that HillÕs [J. Mech. Phys. Solids 12 (1964) 199, 213] bounds, although best possible in terms of volume fraction, are of limited value in so far as HillÕs upper bound lies far above any practical limit for a fibre reinforced material, whereas HillÕs lower bound loses its bounding property when extended to non-linear behaviour via an incremental scheme. This latter effect can be corrected by changing slightly HillÕs derivation in a way that preserves the bounding property. Finally, implications are given for the derivation of in situ matrix flow stress curves from experimental tensile curves on fibre reinforced composites. It is suggested that linear three-point bounds can in practice be used for this purpose.

Statistical analysis of real and simulated fibre arrangements in unidirectional composites

“…Fibre arrangements in unidirectional (UD) composites are typically non-uniform and nonperiodic. Effects of the non-uniform fibre distribution on the composite overall behaviour have been extensively studied in the literature [1][2][3][4][5][6][7]. It is generally agreed that periodic fibre distributions lead to incorrect predictions of the elastic-plastic behaviour under transverse loading conditions [8][9][10].…”

The influence of the representative volume element (RVE) size on the homogenized response of cured fiber composites

“…In this study, the focus is on the state of a cured matrix and the fibers within a fiber tow. It has been noted in previous related studies that the macroscopic response of a fiber tow is dependent on the shape and packing of the fibers [13,14]. Therefore, the objective of this paper is to understand the state of stress evolution within a fiber tow representative volume element (RVE) due to curing as a function of fiber packing.…”

Investigation on the Primary Si Phase Solidification and the Properties of SiC_w/Al-18Si Composites

“…Both SiC whisker and Sr addition can change the solidification behaviors of Al-18Si significantly, increase the degree of supercooling and refine the average size of Si phase of Al-18Si. On the other hand, SiC whisker has effect on the bearing of load and the restraining of crack tip opening, and benefits properties of Al-18Si [6]. These improve tensile strength, Young's modulus and mechanical properties of the composites [7].…”