Non-destructive technique for determining the elastic properties in carbon-reinforced polymer laminates using modal frequencies

This work presents a non-destructive technique for determining the elastic properties in carbon-reinforced polymer laminates using modal frequencies. The proposed method combines data from vibration tests with finite element modeling and global optimization. The purpose of the study is to identify the elastic moduli and Poisson’s ratios of orthotropic materials from vibration tests and compare them with some static tests. In the first stage, a design-of-experiments approach is used to construct a plan that includes the elastic properties of the composite lamina. Then, using the ANSYS software package, each design point is analyzed to determine the natural frequencies and mode shapes of the rectangular plate. In the second stage, response surface models are developed to approximate the structural behavior of the composite plate. In parallel, the natural frequencies and mode shapes of a free rectangular composite plate are obtained from experiments using POLYTEC equipment. In the final stage, the material properties are identified by minimizing the error between the numerical and experimental frequencies. Additionally, the elastic modulus of the composite specimens is determined from static tensile tests and compared with the values obtained from the dynamic identification procedure. The results show that the material properties obtained from vibration and static methods may differ. Therefore, this method should be regarded as a partial identification approach, focused on the most significant parameters from a dynamic perspective.