Evaluation of very high cycle fatigue properties for transverse crack initiation in cross‐ply carbon fiber‐reinforced plastic laminates
Tsuyoshi Miyakoshi, Takeru Atsumi, Kensuke Kosugi, Atsushi HOSOI, Terumasa Tsuda, Hiroyuki KAWADA
Abstract
Abstract This paper investigates the transverse crack initiation behaviors of carbon fiber‐reinforced plastics (CFRPs) in the high‐cycle and very high cycle regimes. To accelerate the fatigue test up to the very high cycle fatigue (VHCF) regime, an ultrasonic fatigue testing system that can apply the specimen ultrasonic load at a frequency of 20 kHz was used. The fatigue behavior of cross‐ply CFRP laminates formed with T800S/2592 prepreg was investigated. The fatigue behaviors at N = 10 3 –10 7 cycles and N = 10 8 –10 9 cycles were obtained by hydraulic and ultrasonic fatigue tests, respectively. The slope of the S – N diagram for transverse crack initiation showed a linear decrease in the region of N = 10 3 –10 6 cycles and leveled off over N = 10 6 cycles. Furthermore, no cracks occurred in any specimen tested under the 90°‐layer stress σ 90°max = 44 MPa up to a maximum of N = 6.56 × 10 9 cycles.