Determination of Dynamic Flexural and Shear Moduli of Thick Composite Beams Using Natural Frequencies

Based on natural frequencies, a simple and stable inverse calculation scheme for characterizing the dynamic flexural moduli, the dynamic in-plane shear modulus and the dynamic transverse shear modulus of thick fiber-reinforced composite beams is developed, and is verified by experimental testing. Expressions are derived for the errors in the characterized moduli to the geometry and material properties of the beam samples. The stability of the inverse scheme is validated by two finite element (FE) composite beam models. Impact modal tests are employed to obtain the flexural vibration frequencies of the free-free supported beam sample. The measured frequencies are subsequently used in the inverse scheme to tune the flexural and shear moduli of a Timoshenko beam model.