Strength Evaluation of Unidirectional Carbon Fiber Reinforced Plastic Laminates Based on Tension–Compression Biaxial Stress Tests

Keita GOTO, Masahiro ARAI, Masaomi NISHIMURA, Kazuki DOHI
2017 Journal of the Japan Society for Composite Materials  
Biaxial stress tests ofcarbon fiber reinforced plastic (CFRP)laminates were performed to investigate a failure criterion under biaxial loading. Specimens of unidirectional CFRP prepreg sheets were subjected to a tensile load in the longitudinal fiber direction and a compressive load in the transverse fiber direction. A dedicated jig was used to perform biaxial stress tests with a commonly-used single-axis testing machine. Measurements were obtained by controlling the displacement ratio,theratio
more » ... ment ratio,theratio between compressiveand tensiledisplacements.Themaximum tensileand compressive stresses were then calculated using a constitutive equation. Longitudinal tensile strength markedly dropped with increasing compressive stress in the transverse direction. The failurecriterion ofthebiaxialstress tests was expressed as an ellipse,ofwhich themajorand minor axes were the longitudinal tensile strength and transverse compressive strength, respectively. Moreover,scanning electron microscopy(SEM)observations suggest that fiber/matrix interfacial debonding occurred due to compressive stress, and such debonding could decrease the tensile strength in the longitudinal fiber direction.
doi:10.6089/jscm.43.48 fatcat:xmlkclvtnrec3jgyyy6c3vef2u