Abstract
Essentially, every failure of a short fiber reinforced composite (SFRC) under tension is induced from a matrix failure, the prediction of which is of fundamental importance. This can be achieved only when the homogenized stresses of the matrix are converted into true values in terms of stress concentration factors (SCFs) of the matrix in an SFRC. Such an SCF cannot be determined in the classical way. In this paper, a closed-form formula for the longitudinal tensile SCF in the SFRC is derived from the matrix stresses determined through an elastic approach. The other directional SCFs in an SFRC are the same as those in a continuous fiber composite already available. A bridging model was used to calculate the homogenized stresses explicitly, and a failure prediction of the SFRC with arbitrary fiber aspect ratio and fiber content was made using only the original constituent strength data. Results showed that the volume fraction, the aspect ratio, and the orientation of the fiber all have significant effect on the tensile strength of an SFRC. In a certain range, the tensile strength of an SFRC increases with the increase in fiber aspect ratio and fiber volume content, and the strength of the oriented short fiber is higher than that of the random short fiber arrangement. Good correlations between the predicted and the available measured strengths for a number of SFRCs show the capability of the present method.
Highlights
Short fiber and particle reinforced composites have been widely used in industries, due to their excellent machinability and good mechanical performance [1,2,3]
When the fiber aspect ratio changes, an short fiber reinforced composite (SFRC) can be degraded to a continuous fiber composite or a particle reinforced composite, the study of SFRCs is of universal significance
It can be found that when the fiber aspect ratio is large enough, e.g., ξ = 429, the longitudinal tensile stress concentration factors (SCFs) is always near to unity no matter what the fiber volume fraction is; if the fiber aspect ratio is moderate, e.g., ξ = 25, the longitudinal tensile SCF noticeably differs from unity
Summary
Short fiber (standing for the reinforcement) and particle reinforced composites have been widely used in industries, due to their excellent machinability and good mechanical performance [1,2,3]. Combined the shear-lag model with the laminate analogy method to predict the failure and strength of two-dimensional, randomly oriented SFRCs. the shear-lag theory was used to determine the longitudinal strength of a single-layer SFRC. The shear-lag theory was used to determine the longitudinal strength of a single-layer SFRC This model only calculates a longitudinal stress transfer, and can only predict the axial tensile strength. Whereas the tensile failure a UA SFRC can be assessed in terms of the true stresses, the strength of an SFRC with random fiber orientation can be predicted by subdividing the random SFRC into a series of UA SFRCs. Good correlation between the predicted results of this model and the existing experimental data for a number of SFRCs indicates that this model is valid for the strength prediction of such composites
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