Inverse determination of elastic constants of composite materials

Abstract

Vibration testing, combined with a numerical method, is a potential alternative approach for determining elastic constants of materials because of its nondestructive characteristic, single test, and producing average properties. To simplify the modeling processes and to find better results, the numerical method of combining finite element analysis and a hybrid genetic algorithm is proposed to inversely determine the elastic constants from the vibration testing data in this work. As verified from the available data of literatures, the repeatability and accuracy of the proposed inverse determination method are confirmed. Four composite specimens with different stacking sequence and thickness are used to determine their elastic constants. As applied to obtain the four or five elastic constants of composite materials, the performance of the proposed method is excellent. To obtain the four elastic constant for thin composite plates, it is better to use unidirectional and thick enough laminates. To determine the five elastic constants for thick composite plates, it is suggested to use unidirectional laminates with the length‐to‐thickness ratio less than or equal to 50. To conquer the effect of measurement error or missing frequencies, it is necessary to carefully exclude these frequencies in the objective function, and reasonable results could be obtained by the proposed method. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

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