Effects of Tensile Prestress Level on Impact Value of 50 vol% Continuous Unidirectional 0 Degree Oriented Carbon Fiber Reinforced Epoxy Polymer (CFRP)

Abstract

Effects of tensile prestress level on Charpy impact value (a_uc) of 50 vol% continuous unidirectional 0 degree oriented carbon fiber reinforced epoxy polymer (CFRP) were investigated. Experimental results showed the a_uc at mid-fracture probability P_f = 0.50 induced by a large prestress of 17.6 MPa (109 kJm⁻²) was increased 30% over that (84 kJm⁻²) of slight prestress of 0.25 MPa. The statistically lowest impact value a_s at P_f = 0 calculated by 3-parameter Weibull equation was raised 26% from 73 to 92 kJm⁻² showing increased reliability of part strength. Fracture surface observation showed a flat surface extending through the thickness from the impact side generally extends deeper as prestress level was raised. This may be due to the transition depth in the specimen thickness from compression to tension is deeper during impact as prestress level was increased acting to raise the impact values.