Fiber distribution of long fiber reinforced polyamide and effect of fiber orientation on mechanical behavior

Abstract

The objective of this paper is to research fiber distribution and mechanical behavior (tensile, flexural, and Charpy impact properties) of long fiber reinforced thermoplastic (LFT) plates made by injection molding. The plates were made of long glass fiber reinforced polyamide 6,6 granules and injected using two types of molds, including center‐gated and end‐gated injecting modes, to obtain different fiber orientation state. In addition, end‐gated plate was cut along three directions (0°/45°/90°) to main flow path, in order to experimentally investigate the effects of fiber orientation on mechanical properties. It is found that there is skin‐shell‐transition‐core structure across thickness of plate, resulted from different fiber orientation. Furthermore, end‐gated plate has more obvious fiber orientation at shell and core regions than center‐gated plate. The experimental results demonstrate that fiber orientation has significant effects on modulus, strength, toughness, and full‐field strain evolution. Tensile and flexural properties decrease by over 50%, as the cutting angle with respect to flow direction changes from 0° to 90° in end‐gated plate. Moreover, unnotched and notched strength drops by 66% and 33%, respectively, from 0° to 90° off‐axis angle. These results show apparent mechanical anisotropy of LFT. Shell‐core structure also significantly influences strain distribution and fracture morphology.

Three‐dimensional polymer composite flow simulation and associated fiber orientation prediction for large area extrusion deposition additive manufacturing

“…With the above results, we show that our present 3D flow model and associated fiber orientation analysis can provide useful information in correlating the MEAM processing parameters to the explanation of the fiber orientation formation in the deposition composites. Prior studies have showed the importance of an accurate fiber orientation in understanding the mechanical performances of fiber reinforced composites [52][53][54][55] . Our results can be further implemented in the micromechanical models of fiber filled composites to analyze their macro and micro anisotropic material behaviors (i.e., an important topic in large-format MEAM applications 3 ).…”

Comparative Analysis of the Impact of Additively Manufactured Polymer Tools on the Fiber Configuration of Injection Molded Long-Fiber-Reinforced Thermoplastics

“…Parveen et al [37] achieved comparable results to Hou et al on a disc geometry (2 mm; 75 mm D) and stated that a higher fiber length leads to a wider core region with more fibers aligned transverse to the flow direction at the end of the flow path. Zhu et al [38] compared a centered and an end-gated injecting model. It is found that the end-gated plate has a more defined shell area of 55%, where the fibers align along the main flow direction and a core region of 20%, with fibers aligned perpendicular to it.…”

Effect of process parameters on the mechanical properties of fiber‐reinforced thermoplastics fabricated by direct fiber feeding injection molding

“…In recent years, many scholars have studied the effect factors of the mechanical properties of composites fabricated by DFFIM. [12][13][14] The composites consisting of GF/CF/ABS were fabricated by Hisakura through DFFIM, respectively, and properties comparison and scanning electron microscopy (SEM) observation results revealed that adding low content of CF helped to improve the fiber aggregation phenomenon and enhance the mechanical properties of the composite. 15 Nakao et al completed the direct injection molding experiment of CF-reinforced PA66 by improving the screw and barrel according to DFFIM technology.…”

“…The properties of FRTP are closely related to many factors such as fiber length, fiber content, orientation, distribution and interface bonding, etc. In recent years, many scholars have studied the effect factors of the mechanical properties of composites fabricated by DFFIM 12–14 . The composites consisting of GF/CF/ABS were fabricated by Hisakura through DFFIM, respectively, and properties comparison and scanning electron microscopy (SEM) observation results revealed that adding low content of CF helped to improve the fiber aggregation phenomenon and enhance the mechanical properties of the composite 15 .…”