Effect of Temperature and Strain Rate on Damage Accumulation Behavior of Unidirectional CFRP

Abstract

Carbon Fiber reinforced plastics (CFRP) is consisted with the carbon fiber and matrix resin. It has reported to consider that the matrix resin’s properties also depends on CFRP’s mechanical properties in the recent research. Matrix resin’s considerable mechanical property is viscoelasticity that depends on time and temperature. In this study, we focused on the effect of temperature and strain rate on the damage accumulation behavior of unidirectional CFRP laminate, and tensile tests with acoustic emission technique were carried out at three different temperature with three different strain rate. As the results of tensile tests, lower temperature and higher strain rate showed higher tensile strength, that is, it is understood that tensile strength depended on the matrix’s viscoelastic properties. Crack initiation behavior, which was defined at the point of rapid increase in cumulative AE energy, was depended on the temperature and strain rate. To understand the details of AE information, the frequency analysis was done. In the frequency analysis, the resonant frequency of AE sensors effects on the frequency properties of the detected signals, so we tried to erase the effect of sensors by deconvolution of AE sensor’s frequency properties from detected signals. As the results of deconvolution, we could distinguished the failure modes as matrix cracking, fiber/matrix interfacial debonding and fiber breaking. Using these results, matrix cracking, fiber/matrix interfacial debonding were effected by temperature and strain rate, however, fiber breaking was not affected. Consequently, the crack accumulation behavior of each failure mode depended on the temperature and strain rate as the same tendency of matrix’s viscoelastic properties.