It is generally accepted that fracture toughness of fiber-reinforced polymer composites is affected by strain rate in an atmospheric pressure condition. For a present study, the strain rate effect on the fracture toughness of fiber-reinforced laminated composites in the hydrostatic pressure condition was investigated. For this purpose, fracture tests have been conducted using graphite/epoxy laminated composites applying three steps of the strain rate at 270 MPa hydrostatic pressure condition. The strain rates applied were 0.05 %/sec, 0.25 %/sec, and 0.55 %/sec. Fracture toughness was determined from the work factor approach as a function of applied strain rate. The result showed that fracture toughness decreased as the strain rate increased. Specifically, the fracture toughness decreased 12% as the strain rate increased from 0.05 %/sec to 0.55 %/sec.
