Fiber Length and Orientation in Long-Fiber Injection-Molded Thermoplastics — Part I: Modeling of Microstructure and Elastic Properties

Abstract

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

Prediction of the Fiber Orientation State and the Resulting Structural and Thermal Properties of Fiber Reinforced Additive Manufactured Composites Fabricated Using the Big Area Additive Manufacturing Process

“…In Jack and Smith [22] closed form expressions for the stiffness expectation and variance were derived using complex spherical harmonics. Nguyen et al [36] performed a comparison between the E 1 and E 2 predicted by the IRD-RSC model and tensile tests. Recently Nguyen et al [31] used the ARD model to predict the fiber orientation and the subsequent stress response for an injection molded long fiber thermoplastic.…”

PNNL Technical Support to The Implementation of EMTA and EMTA-NLA Models in Autodesk? Moldflow? Packages

“…The predicted flow (18030 MPa) and cross-flow (13071 MPa) moduli at the center of the plaque agree with the experimental results (16100 MPa and 11400 MPa) within 15%. A similar analysis was conducted for an edge-gated 40%-weight-fraction long-glassfiber/polypropylene plaque (90 mm x 80 mm x 3mm) studied in [1][2][3]. Figures 5(a) and 5(b) present the contours of fiber orientation tensor components A 11 and A 22 in a core layer of this plaque.…”

“…The first application illustrates the ASMI analysis of a large 50%-weight-fraction long-glassfiber/polyamide 6,6 (PA6,6) plaque (305 mm x 305 mm x 2.8 mm") from injection molding simulation to elastic properties prediction using the EMTA elastic model accounting for fiber length and orientation distribution [1]. Figure 1 shows the ASMI finite element mesh for the injection molding simulation of this plaque.…”

Comportamiento de Sistemas Provisionales de Protección de Borde de polietileno de alta densidad frente a cargas estáticas y de impacto

“…More specifically, the addition of glass fiber in cut threads to a HDPE matrix produces a compound material of longitudinal elasticity module and fracture strength higher for HDPE under static loads (7,8), lower fluency coefficients (9) and greater impact strength (10).…”

“…En particular la adición de fibra de vidrio en forma de hilos cortados a una matriz de PEAD produce un material compuesto con valores de módulo de elasticidad longitudinal y tensión de rotura superiores a los del PEAD bajo cargas estáticas (7,8), menores coeficientes de fluencia (9) y mayor resistencia a impacto (10).…”