By virtue of the comparability between the wave superposition method and the dynamic analysis of structures, a general format for overcoming the non-uniqueness of solution induced by the wave superposition method at t...By virtue of the comparability between the wave superposition method and the dynamic analysis of structures, a general format for overcoming the non-uniqueness of solution induced by the wave superposition method at the eigenfrequencies of the corresponding interior problems is proposed. By adding appropriate damp to the virtual source system of the wave superposition method, the unique solutions for all wave numbers can be ensured. Based on this thought, a novel method-wave superposition method with complex radius vector is constructed. Not only is the computational time of this method approximately equal to that of the standard wave superposition method, but also the accuracy is much higher compared with other correlative methods. Finally, by taking the pulsating sphere and oscillating sphere as examples, the results of calculation show that the present method can effectively overcome the non-uniqueness problem.展开更多
Ocean boundaries present a significant effect on the vibroacoustic characteristics and sound propagation of an elastic structure in practice.In this study,an efficient finite element/wave superposition method(FE/WSM)f...Ocean boundaries present a significant effect on the vibroacoustic characteristics and sound propagation of an elastic structure in practice.In this study,an efficient finite element/wave superposition method(FE/WSM)for predicting the three-dimen-sional acoustic radiation from an arbitrary-shaped radiator in Pekeris waveguides with a lossy seabed is proposed.The method is based on the FE method(FEM),WSM,and sound propagation models.First,a near-field vibroacoustic model is established by the FEM to obtain vibration information on a radiator surface.Then,the WSM based on the Helmholtz boundary integral is used to pre-dict the far-field acoustic radiation and propagation.Furthermore,the rigorous image source method and complex normal mode are employed to obtain the near-and far-field Green’s function(GF),respectively.The former,which is based on the spherical wave decomposition,is adopted to accurately solve the near-field source strength,and the far-field acoustic radiation is calculated by the latter and perturbation theory.The simulations of both models are compared to theoretical wavenumber integration solutions.Finally,numerical experiments on elastic spherical and cylindrical shells in Pekeris waveguides are presented to validate the accuracy and efficiency of the proposed method.The results show that the FE/WSM is adaptable to complex radiators and ocean-acoustic envi-ronments,and are easy to implement and computationally efficient in calculating the structural vibration,acoustic radiation,and sound propagation of arbitrarily shaped radiators in practical ocean environments.展开更多
After borrowing the idea of precise integration method, a precise integration transfer matrix method （PITMM） is proposed by modifying traditional transfer matrix method. The submarine hull can be modeled as joined c...After borrowing the idea of precise integration method, a precise integration transfer matrix method （PITMM） is proposed by modifying traditional transfer matrix method. The submarine hull can be modeled as joined conical- cylindrical-spherical shells. By considering the effect of the ring-stiffeners, the field transfer matrixes of shells of revolution are obtained accurately by PITMM. After assembling the field transfer matrixes into an entire matrix, the dynamic model is established to solve the dynamic responses of the joined shell. By describing the sound pressure in fluid by modified wave superposition method （MWSM） and collocating points along the meridian line of the joined shell, finally the structural and acoustic responses of a finite stiffened submarine hull can be predicted by coupled PITMM and MWSM. The effectiveness of the present method has been verified by comparing the structural and acoustic responses of the spherical shell with existing results. Furthermore, the effects of the model truncation, stiffness and thickness on the structural and acoustic responses of the submarine hull are studied.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 10172038).
文摘By virtue of the comparability between the wave superposition method and the dynamic analysis of structures, a general format for overcoming the non-uniqueness of solution induced by the wave superposition method at the eigenfrequencies of the corresponding interior problems is proposed. By adding appropriate damp to the virtual source system of the wave superposition method, the unique solutions for all wave numbers can be ensured. Based on this thought, a novel method-wave superposition method with complex radius vector is constructed. Not only is the computational time of this method approximately equal to that of the standard wave superposition method, but also the accuracy is much higher compared with other correlative methods. Finally, by taking the pulsating sphere and oscillating sphere as examples, the results of calculation show that the present method can effectively overcome the non-uniqueness problem.
基金financially supported by the National Key Research and Development Plan of China (No. 2016YFC1401203)the National Natural Science Foundation of China (Nos. 42006168 and 11404079)
文摘Ocean boundaries present a significant effect on the vibroacoustic characteristics and sound propagation of an elastic structure in practice.In this study,an efficient finite element/wave superposition method(FE/WSM)for predicting the three-dimen-sional acoustic radiation from an arbitrary-shaped radiator in Pekeris waveguides with a lossy seabed is proposed.The method is based on the FE method(FEM),WSM,and sound propagation models.First,a near-field vibroacoustic model is established by the FEM to obtain vibration information on a radiator surface.Then,the WSM based on the Helmholtz boundary integral is used to pre-dict the far-field acoustic radiation and propagation.Furthermore,the rigorous image source method and complex normal mode are employed to obtain the near-and far-field Green’s function(GF),respectively.The former,which is based on the spherical wave decomposition,is adopted to accurately solve the near-field source strength,and the far-field acoustic radiation is calculated by the latter and perturbation theory.The simulations of both models are compared to theoretical wavenumber integration solutions.Finally,numerical experiments on elastic spherical and cylindrical shells in Pekeris waveguides are presented to validate the accuracy and efficiency of the proposed method.The results show that the FE/WSM is adaptable to complex radiators and ocean-acoustic envi-ronments,and are easy to implement and computationally efficient in calculating the structural vibration,acoustic radiation,and sound propagation of arbitrarily shaped radiators in practical ocean environments.
基金supported by the National Natural Science Foundation of China(Grant No.51409200)China Postdoctoral Science Foundation(Grant No.2015M582290)
文摘After borrowing the idea of precise integration method, a precise integration transfer matrix method （PITMM） is proposed by modifying traditional transfer matrix method. The submarine hull can be modeled as joined conical- cylindrical-spherical shells. By considering the effect of the ring-stiffeners, the field transfer matrixes of shells of revolution are obtained accurately by PITMM. After assembling the field transfer matrixes into an entire matrix, the dynamic model is established to solve the dynamic responses of the joined shell. By describing the sound pressure in fluid by modified wave superposition method （MWSM） and collocating points along the meridian line of the joined shell, finally the structural and acoustic responses of a finite stiffened submarine hull can be predicted by coupled PITMM and MWSM. The effectiveness of the present method has been verified by comparing the structural and acoustic responses of the spherical shell with existing results. Furthermore, the effects of the model truncation, stiffness and thickness on the structural and acoustic responses of the submarine hull are studied.
