Characterizing viscoelastic properties of carbon fiber/epoxy composites using vector fitting method

In this work, mechanical properties of a T800 carbon fiber/modified epoxy composite material were researched by using a dynamic mechanical analyzer (DMA) operated under flexural mode. The dynamic mechanical behavior was investigated by DMA at a fixed frequency of 1 Hz. Because mechanical properties of the material were influenced by both time and temperature, its viscoelastic modulus was also considered and accomplished by conducting DMA multiple‐frequency dynamic mechanical experiments. Based on the experimental data, master curves of the storage (E′) and the loss moduli (E″) at a pre‐selected reference temperature were constructed as a function of frequency. The shift factor along the frequency axis was also determined as a function of temperature. Expression of the relaxation modulus in the time domain at the reference temperature was obtained by using vector fitting method. The numerical algorithm result showed excellent correlation to experimental data over the entire range of relaxation. POLYM. COMPOS., 39:E2000–E2005, 2018. © 2017 Society of Plastics Engineers