Acoustic scattering from submerged laminated composite cylindrical shells

The scattering of an oblique plane progressive monochromatic acoustic field upon a laminated composite cylindrical shell is studied based on the three-dimensional exact equations of anisotropic elasticity. Each layer of laminated structure is made of helically filament wound (fiber reinforced) homogeneous material whose degree of anisotropy is considered as monoclinic type. An approximate laminate model along with the local transfer matrix solution is used to solve the state space governing formulation within each layer. Considering the perfect bonding between the adjacent layers, the global transfer matrix is constructed as the product of the local transfer matrices employed to solve for the unknown scattering coefficients. The so-called back-scattered form function amplitude is evaluated for two cases of (strong anisotropy) Graphite/Epoxy and (weak anisotropy) Glass/Epoxy multilayered cylindrical shells, for different number of layers and different stacking sequence. Furthermore, the axisymmetric and non-axisymmetric dynamic behavior of the composite shells are studied by evaluating the directivity patterns of the far-field form function amplitude at the selected resonance frequency corresponding to the first overtone of n = 2 vibration mode. Some limiting cases are considered and good agreements with the solutions available in the literature are obtained.