Toroidal wave in multilayered spherical curved plates

For the purpose of ultrasonic nondestructive inspection of layered spherical curved plates, characteristics of guided waves in multilayered spherical curved plates are studied using an improved orthogonal polynomial series method. Conventional polynomial series method has been used to solve wave motion in the multilayered flat plate for about four decades. However, it can deal with the layered structure only when the material properties of two adjacent layers do not change significantly. It also can not obtain correct and continuous normal stress profiles. Numerical comparisons verify that the improved polynomial method overcomes these drawbacks. Then, the influences of radius to thickness ratio, volume fraction and stacking sequence on dispersion curves and stress distributions are discussed. It is found that the radius to thickness ratio, the wave speed of component material and the position of the component material determine the distribution of mechanical energy at higher frequencies.