Uncertainty characterization of guided ultrasonic wave properties in composite materials

Guided ultrasonic wave-based methods are promising for structural health monitoring of isotropic and composite materials and structures. The technology has seen a lot of attention in the research community over the past decades, and many analytical and numerical methods have been developed to describe different aspects of guided wave propagation and scattering phenomena as well as damage detection. However, very little research was geared towards the influence of the uncertainty in the material properties for the calculation of the dispersion curves. The lack of knowledge of the exact material properties together with manufacturing tolerances could lead to erroneous conclusions. Hence, in this study, an uncertainty analysis for the material properties of fiber-reinforced composites is conducted to quantify the effect of uncertain material constants on the dispersion curves. A fuzzy arithmetical approach based on the Transformation Method is used to generate the dispersion curves with uncertain parameters in conjunction with a root-finding algorithm. The uncertain parameters are modeled as linear fuzzy numbers. Using triangular membership functions, both the nominal value and the worst-case interval are adequately combined into one fuzzy number. Furthermore, it is shown that the measure of influence for the uncertain material parameters on the group velocities of the considered Lamb waves is not equally weighted. These findings might allow for the development of efficient, nondestructive material characterization techniques in the future.