Improved Mean Value‐Amplitude Method for Determination of Orientation‐Dependent Modulus of Short Fiber‐Reinforced Thermoplastics

Abstract

Short fiber‐reinforced thermoplastics such as 30% by weight glass fiber‐reinforced polyamide 46 (PA46GF30) are considered as substitute material for lightweight metallic parts. Despite the short fiber length, a distinct fiber orientation caused by local shear flow conditions during injection molding is obtained. This results in anisotropic material properties, which should be considered in the design phase of a component. Material properties are obtained by mechanical testing, e.g., tensile tests of specimens. These specimens have their own inherent microstructure consisting of different layers with different fiber orientations. The recently proposed mean value‐amplitude method enables the correlation of the Young's modulus to the eigenvalues of the fiber orientation tensor. The study presented herein applies a physically based improvement of the mean value‐amplitude method by consideration of the real fiber length. The results are very accurate for the description of the anisotropic material behavior and can be implemented in simulation tools for component design very easily.