Anomalous dispersion of flexural guided waves in clad rods

In clad rods, the dispersion properties of firstorder flexural [F(1, 1)] modes can differ from other modes. Normal and Stoneley modes and the existence criteria for four F(1, 1) modes are investigated. We focus on low-frequency anomalous dispersion, which occurs only in F(1, 1) modes and is sensitive to shear velocity.