SIMULTANEOUS RESONANCE CASES IN A PITCH – ROLL SHIP MODEL. PART 2: NUMERICAL ANALYSIS
- 1 Faculty of Naval Electro mechanics, Maritime University of Constanta, Romania
In a companion paper, the response of a two-degrees-of-freedom ship model with nonlinear coupled pitch and roll modes under sinusoidal harmonic excitation was studied analytically by means of the Multiple Scales method for the case where the pitch frequency is twice the roll frequency. Five resonant cases were analysed and the governing equations for the transition towards the steady-state solutions, the first-order approximations for these solutions and the frequency-amplitude relationships were derived. The present contribution aimed to verify the accuracy of the analytical results by contrasting them with the numerical results provided by direct integration of the equations of motion. The two sets of results were found to be in excellent or, at least, in decent agreement every time the system parameters were selected without a flagrant violation of the order’s magnitude.