Free vibration analysis of multilayered composite plates and shells with the natural approach Original Research Article

Natural curved triangular shell element NATCOP developed in [1] is employed to vibration mode analysis of multilayered composite plates and shells. The shells can be either symmetric or unsymmetric. The spectral transformation Lanczos method with selective or full orthogonalization is used to solve the eigenvalue problem of a pencil (K, M). Proper shifting of the eigenvalues is essential for the success of this method; certain problems associated with the shift are discussed. Several numerical examples, including symmetric and unsymmetric composite plates and unsymmetric composite conical shells, are tested and show that element NATCOP is also efficient and reliable for free vibration analysis.