An iterative method for identification of temperature and amplitude dependent material parameters of fiber-reinforced polymer composites

Abstract

Temperature and amplitude dependent material properties have been observed for fiber-reinforced polymer composites (FRPCs) in previous studies. Accurate identification of the nonlinear material parameters is the basis of evaluation and optimization design of FRPCs. This paper proposes an iterative method based on differential evolution algorithm (DEA) for identifying the amplitude and temperature dependent material parameters of FRPCs. Initially, the expressions of complex elastic and shear moduli of FRPCs involving temperature and amplitude dependent fitting coefficients are proposed, upon which the iterative identification principle for nonlinear elastic and shear moduli and loss factors of FRPCs are clarified. Then, a series of dynamic experiments are conducted on FRPC plate specimens in thermal vibration environment from 20°C to 160°C with the excitation amplitude varied from 0.1g to 1.2g. The experimental data are adopted to identify the unknown fitting coefficients. Finally, the nonlinear elastic and shear moduli as well as loss factors of another specimen are determined via the proposed method, upon which the natural frequencies and damping ratios are achieved and compared to the measured results to validate the proposed identification approach. The effects of DEA key parameters on the iterative accuracy and efficiency are also discussed. From comparisons of identification results and experimental data, it can be seen the calculation errors of natural frequencies and damping ratios associated with the first four modes of FRPC plate are no more than 6.98 % and 13.34 %, respectively, which is acceptable for engineering applications.