Abstract
In this work we present for the first time an approach for identifying the geometric and material characteristics of layered composite structures through an inverse wave and finite element approach. More specifically, this Non-Destructive Evaluation (NDE) approach is able to recover the thickness, density, as well as all independent mechanical characteristics such as the tensile and shear moduli for each layer of the composite structure under investigation. This is achieved through multi-frequency single shot measurements. It is emphasized that the success of the approach is independent of the employed excitation frequency regime, meaning that both structural dynamics and ultrasound frequency spectra can be employed. It is demonstrated that more efficient convergence of the identification process is attained closer to the bending-to-shear transition range of the layered structure. Since a full FE description is employed for the periodic composite, the presented approach is able to account for structures of arbitrary complexity. The procedure is applied to a sandwich panel with composite facesheets and results are compared with two wave-based characterization techniques: the Inhomogeneous Wave Correlation method and the Transition Frequency Characterization method. Numerical simulations and experimental results are presented to verify the robustness of the proposed method.
Highlights
Composites are widely used in modern industry, due to their low density and high dynamic and static performances
The Wave and Finite Element (WFE) method was introduced in [7, 8] in order to facilitate the post-processing of the eigenproblem solutions
The identified Young’s modulus for the skins of the laminate and the shear modulus of the honeycomb core in the direction under investigation are computed as: EWFE = 69.5 GPa and GWFE = 37.1 MPa which are both in very good agreement with the values provided by the other methods mentioned above, experimentally validating the exhibited computational scheme
Summary
Composites are widely used in modern industry, due to their low density and high dynamic and static performances. Many methods have been developed to perform material characterization in composites. FE-based wave propagation within periodic structures was firstly considered in [6]. The WFE has recently found applications in predicting the vibroacoustic and dynamic performance of composite panels and shells [9,10,11] , with complex periodic structures [12, 13] having been investigated. The principal novel contribution of this work is the development of a comprehensive methodology coupling periodic structure theory to FE in order to identify the characteristics of each individual layer of a composite structure through experimental measurements on the entire structure. The paper is organised as follows: In Sec. the FE computational scheme for predicting wave propagation in multilayered structures is presented.
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