Experimental investigation of the very high cycle fatigue of GFRP [90/0]s cross-ply specimens subjected to high-frequency four-point bending

Very High Cycle Fatigue (VHCF) Characteristics of Carbon Fiber Reinforced Plastics (CFRP) under Ultrasonic Loading

“…After a suitable cooling method was determined, the CFRP specimens were ultrasonically loaded and a stress ratio R of 0.2 and 0.35 was used. During the loading of the specimen, the test was stopped if the resonance frequency decreased by more than 10 Hz/s, the cycle number was >10 9 , or the temperature of the specimen surface was >90 °C. Figure 7 shows the corresponding fatigue S-N curve.…”

“…However, most of the current research on composite materials focuses on the static failure or the low cycle fatigue, whereas experimental research on high cycle fatigue (HCF) and very high cycle fatigue (VHCF) is still very scarce [8]. The testing frequency [9] and the heating of the specimen [10] are key factors restricting the fatigue study of composite materials. Carlile et al [11] and Curtis et al [12] considered these issues to reduce the fatigue strength of APC-2/AS4 laminates.…”

“…In 1997, Couillard et al [13] studied the fatigue performance of CFRP under low frequency loading. In 2006, Silvain et al [14] studied carbon fiber composite materials at low frequencies within 0.5-10 Hz and high frequencies within 57-158 Hz and extended the loading cycles to over 10 9 . They concluded that damage still occurs in the VHCF regime.…”

“…Their results showed that the specimens break perpendicularly to the ply direction in the VHCF regime and cause a significant decrease in stiffness. In 2014, Adam et al [9] completed a very high cycle fatigue study of [90/0] s glass fiber braided composites with cyclic four point bending at frequencies within 50-80 Hz. Their results indicated that the crack propagation along the direction of the thickness was retarded under a low load and that delamination was delayed.…”

Textile‐Reinforced Thermoplastics for Compliant Mechanisms – Application and Material Phenomena

“…As expected, a significant dependency of stiffness degradation from the maximum stress can be recognized. [8,9] Here, a time-dependent creep like behavior due to mean stresses gains more importance and acts as a driver of degradation. Usually the first phase of degradation is related to the initiation and growth of inter fiber cracks in off-axis layers or textile filaments, respectively.…”