Zusammenfassung
This article develops a methodology to predict the elastic properties
of long-fiber injection-molded thermoplastics (LFTs). The corrected
experimental fiber length distribution and the predicted and experimental
orientation distributions were used in modeling to compute the elastic
properties of the composite. First, from the fiber length distribution
(FLD) data in terms of number of fibers versus fiber length, the
probability density functions were built and used in the computation.
The two-parameter Weibull's distribution was also used to represent
the actual FLD. Next, the Mori—Tanaka model that employs the Eshelby's
equivalent inclusion method was applied to calculate the stiffness
matrix of the aligned fiber composite containing the established
FLD. The stiffness of the actual as-formed composite was then determined
from the stiffness of the computed aligned fiber composite that was
averaged over all possible orientations using the orientation averaging
method. The methodology to predict the elastic properties of LFTs
was validated via experimental verification of the longitudinal and
transverse moduli determined for long glass fiber injection-molded
polypropylene specimens. Finally, a sensitivity analysis was conducted
to determine the effect of a variation of FLD on the composite elastic
properties. Our analysis shows that it is essential to obtain an
accurate fiber orientation distribution and a realistic fiber length
distribution to accurately predict the composite properties.
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