Results
Title

Fatigue Properties of Carbon Fiber–Reinforced Foams and Experimental Observation of the Damage Growth Mechanism.

Authors

Sano, Ryuto; Koga, Yuta; Sato, Yusuke; Kikuchi, Takuto; Hosoi, Atsushi; Kawahara, Kota; Takebe, Yoshiki; Kawada, Hiroyuki

Abstract

Carbon fiber–reinforced foams (CFRFs) are expanded thermoplastic composite materials reinforced with three‐dimensional discontinuous carbon fibers. Herein, the effects of their unique internal structure on fatigue properties were investigated. Through tension‐tension fatigue tests and the digital image correlation (DIC) method, distinct stiffness reduction behavior was observed across the entire specimen and at the fracture points. The results suggest that local stiffness reduction behavior affects the fatigue properties. From the DIC method, damage was observed by scanning electron microscopy and the fiber tortuosity, and the void fraction were quantified using X‐ray computed tomography scans. In the case of three‐dimensional oriented fibers, stress was concentrated at fiber ends, fiber intersections, and bent fibers, resulting in fiber pull‐outs and matrix cracks. In the case of voids, the void size affected damage development, and the stress concentration around the voids caused fiber fracture and matrix cracks.

Subjects

THERMOPLASTIC composites; POROSITY; DIGITAL image correlation; CARBON foams; STRESS concentration

Publication

Fatigue & Fracture of Engineering Materials & Structures, 2025, Vol 48, Issue 2, p967

ISSN

8756-758X

Publication type

Academic Journal

DOI

10.1111/ffe.14518