TITLE:
Effect of Needle Punching Process on a Chopped Strand Mat Composite with an Open Hole
AUTHORS:
Daiki Ichikawa, Hiroyuki Hamada, Akio Ohtani
KEYWORDS:
Fiber-Reinforced Plastic, Needle Punch, Chopped Strand Mat, Open Hole, Characteristic Distance
JOURNAL NAME:
Open Journal of Composite Materials,
Vol.8 No.3,
July
19,
2018
ABSTRACT: The
easiest and most reliable joining method is the mechanical joint with a bolt
and nut or rivet. However, in the case of composite laminates, mechanical joint
properties decrease because of lower interlaminar properties compared to
in-plane properties around hole.This study investigated needle punching process with the aim of
improving the mechanical properties in the thickness direction of
fiber-reinforced plastic composite laminates with an open hole. Needle punching
process was applied to glass fiber chopped strand matused as the reinforcement
for the composite laminates. Open-hole tensile tests and observations of end
cross-sections after the tests were performed. The tensile properties and
fracture mechanism of the specimens subjected to needle punching process were
investigated. In addition, characteristic distance (a parameter for evaluating
resistance to fracture in open-hole tensile test specimens) was also calculated
to examine the effects of needle punching process conditions on fracture toughness.
Tensile strength was improved by more than 15% by needle punching process.
However, when a certain needle punching density was exceeded, the mechanical
properties worsened. In addition, characteristic distance increased with
increasing needle punching density. Thus, these results suggest that there is
an optimal needle punching density with respect to strength and characteristic
distance.