Experimental study on carbon fiber/epoxy laminates under dynamic tensile and their damage analysis

Tensile tests were carried out on two kinds of carbon fiber/epoxy laminates specimen ( (45/-45)_4S and (0/45/90/-45)_2S) at quasi-static (strain rate 10^-5~10^-4 s^-1)，intermediate (strain rate 10^-1~10¹ s^-1) and  high strain rate (strain rate 10²~10⁴ s^-1) using the MTS material machine and tensile split Hopkinson bar. A damage constitutive model based on the damage energy release rate was derived within a thermodynamic framework to analyze the dynamic failure of carbon fiber/epoxy. Three damage evolution laws associated with three damage mechanisms (fiber breakage，matrix cracking and shear in plane) were proposed. A procedure resembling the regularization used in viscoplasticity was adopted to take the strain rate into account on damage evolution. The model was coded and implemented into finite element software. The tests were simulated using the model，and the results verify that the model can simulate the dynamic tensile failure well for carbon fiber/epoxy laminates.