2017 Volume 43 Issue 3 Pages 81-89
The bonding property of interfaces between matrix polymers and fibers directly affects mechanical properties of injection molded parts of short-fiber reinforced thermoplastics. The bonding property is an important factor for predicting accurate deformation of the parts. Hence, we have evaluated micromechanics models proposed by Nairn et al. and Hashin, which can consider a degree of the bonding by defining a spring constant on the interface. In this paper, the Nairn–Hashin (NH) models are examined using injection molded square plates of short glass fiber reinforced polypropylene. The spring constants and the tensors of fiber orientation are first identified by measuring the elastic moduli for small specimens cut out from several locations and directions in the molded plates. Stiffness matrices are then calculated from the spring constants and the tensors with the NH models. By using the stiffness matrices, finite element analyses are finally performed for bending specimens cut out from the molded plates. The values for the simulated bending loads of the specimens almost agreed with the measured ones.
