To study the stiffness distribution of girder and the method to identify modal parameters of cable-stayed bridge, a simplified dynamical finite element method model named three beams model was established for the gird...To study the stiffness distribution of girder and the method to identify modal parameters of cable-stayed bridge, a simplified dynamical finite element method model named three beams model was established for the girder with double ribs. Based on the simplified model four stiffness formulae were deduced according to Hamilton principle. These formulae reflect well the contribution of the flexural, shearing, free torsion and restricted torsion deformation, respectively. An identification method about modal parameters was put forward by combining method of peak value and power spectral density according to modal test under ambient excitation. The dynamic finite element method analysis and modal test were carried out in a long-span concrete cable-stayed bridge. The results show that the errors of frequencies between theoretical analysis and test results are less than 10% mostly, and the most important modal parameters for cable-stayed bridge are determined to be the longitudinal floating mode, the first vertical flexural mode and the first torsional mode, which demonstrate that the method of stiffness distribution for three beams model is accurate and method to identify modal parameters is effective under ambient excitation modal test.展开更多
The armored cable used in a deep-sea remotely operated vehicle(ROV) may undergo large displacement motion when subjected to dynamic actions of ship heave motion and ocean current. A novel geometrically exact finite el...The armored cable used in a deep-sea remotely operated vehicle(ROV) may undergo large displacement motion when subjected to dynamic actions of ship heave motion and ocean current. A novel geometrically exact finite element model for two-dimensional dynamic analysis of armored cable is presented. This model accounts for the geometric nonlinearities of large displacement of the armored cable, and effects of axial load and bending stiffness. The governing equations are derived by consistent linearization and finite element discretization of the total weak form of the armored cable system, and solved by the Newmark time integration method. To make the solution procedure avoid falling into the local extreme points, a simple adaptive stepping strategy is proposed. The presented model is validated via actual measured data. Results for dynamic configurations, motion and tension of both ends of the armored cable, and resonance-zone are presented for two numerical cases, including the dynamic analysis under the case of only ship heave motion and the case of joint action of ship heave motion and ocean current. The dynamics analysis can provide important reference for the design or product selection of the armored cable in a deep-sea ROV system so as to improve the safety of its marine operation under the sea state of 4 or above.展开更多
The coupled model of a four-cylinder internal combustion engine and a dash panel was constructed to analyze the relationship between the engine noise and interior noise of an automobile. Finite element analysis, flexi...The coupled model of a four-cylinder internal combustion engine and a dash panel was constructed to analyze the relationship between the engine noise and interior noise of an automobile. Finite element analysis, flexible multi-body dynamics, and boundary element analysis were integrated to obtain the tetrahedron-element models, structural vibration response, and radiated noise,respectively. The accuracy of the finite-element model of the engine was validated by modal analysis via single-input multi-output technology, while the dash panel was validated by sound transmission loss experiment. The block was optimized to reduce the radiated acoustic power from the engine surface. The acoustic transfer path between the engine cabin and passenger compartment was then established. The coupled analysis results reveal that the interior noise is optimized due to the engine noise reduction.展开更多
基金Project(50608008) supported by the National Natural Science Foundation of Chinaproject(20050536002) supported by the Specialized Research Fund for the Doctoral Program of Higher Education
文摘To study the stiffness distribution of girder and the method to identify modal parameters of cable-stayed bridge, a simplified dynamical finite element method model named three beams model was established for the girder with double ribs. Based on the simplified model four stiffness formulae were deduced according to Hamilton principle. These formulae reflect well the contribution of the flexural, shearing, free torsion and restricted torsion deformation, respectively. An identification method about modal parameters was put forward by combining method of peak value and power spectral density according to modal test under ambient excitation. The dynamic finite element method analysis and modal test were carried out in a long-span concrete cable-stayed bridge. The results show that the errors of frequencies between theoretical analysis and test results are less than 10% mostly, and the most important modal parameters for cable-stayed bridge are determined to be the longitudinal floating mode, the first vertical flexural mode and the first torsional mode, which demonstrate that the method of stiffness distribution for three beams model is accurate and method to identify modal parameters is effective under ambient excitation modal test.
基金Project(2008AA09Z201)supported by the National High Technology Research and Development Program of China
文摘The armored cable used in a deep-sea remotely operated vehicle(ROV) may undergo large displacement motion when subjected to dynamic actions of ship heave motion and ocean current. A novel geometrically exact finite element model for two-dimensional dynamic analysis of armored cable is presented. This model accounts for the geometric nonlinearities of large displacement of the armored cable, and effects of axial load and bending stiffness. The governing equations are derived by consistent linearization and finite element discretization of the total weak form of the armored cable system, and solved by the Newmark time integration method. To make the solution procedure avoid falling into the local extreme points, a simple adaptive stepping strategy is proposed. The presented model is validated via actual measured data. Results for dynamic configurations, motion and tension of both ends of the armored cable, and resonance-zone are presented for two numerical cases, including the dynamic analysis under the case of only ship heave motion and the case of joint action of ship heave motion and ocean current. The dynamics analysis can provide important reference for the design or product selection of the armored cable in a deep-sea ROV system so as to improve the safety of its marine operation under the sea state of 4 or above.
基金Project(2011BAE22B05)supported by the 12th Five-year National Key Projects of Science and Technology Support Plan,China
文摘The coupled model of a four-cylinder internal combustion engine and a dash panel was constructed to analyze the relationship between the engine noise and interior noise of an automobile. Finite element analysis, flexible multi-body dynamics, and boundary element analysis were integrated to obtain the tetrahedron-element models, structural vibration response, and radiated noise,respectively. The accuracy of the finite-element model of the engine was validated by modal analysis via single-input multi-output technology, while the dash panel was validated by sound transmission loss experiment. The block was optimized to reduce the radiated acoustic power from the engine surface. The acoustic transfer path between the engine cabin and passenger compartment was then established. The coupled analysis results reveal that the interior noise is optimized due to the engine noise reduction.
