The Experts below are selected from a list of 90 Experts worldwide ranked by ideXlab platform
Jian Liu - One of the best experts on this subject based on the ideXlab platform.
-
probabilistic interval perturbation methods for hybrid uncertain acoustic field prediction
Journal of Vibration and Acoustics, 2013Co-Authors: Baizhan Xia, Jian LiuAbstract:For the hybrid uncertain acoustic field prediction with random and interval variables, the random interval Dynamic Equilibrium Equation is established and two hybrid probabilistic interval perturbation methods, named as hybrid perturbation Monte Carlo method (HPMCM) and hybrid perturbation vertex method (HPVM), are present. In HPMCM, the intervals of expectation and variance of sound pressure are calculated by a combination of the random interval matrix perturbation method, the random interval moment method and Monte Carlo method. In HPVM, the intervals of expectation and variance of sound pressure are calculated by a combination of the random interval matrix perturbation method, the random interval moment method and the vertex method. Numerical results on a 2D acoustic tube, the 2D acoustic cavity of a car and a 3D acoustic cavity verify the effectiveness and the high efficiency of HPVM when compared with HPMCM. HPVM can be considered as an effective engineering method to quantify the effects of parametric uncertainty on the sound pressure response.
-
Interval and subinterval perturbation methods for a structural-acoustic system with interval parameters
Journal of Fluids and Structures, 2013Co-Authors: Baizhan Xia, Jian LiuAbstract:Abstract Interval and subinterval perturbation methods have been widely applied in response analyses of the uncertain structure with interval parameters. In this paper, based on the characteristics of structural-acoustic systems, the interval and subinterval perturbation methods are extended to calculate the frequency response intervals of a structural-acoustic system with interval parameters. In the extended methods, the interval Dynamic Equilibrium Equation of the structural-acoustic system is established, and interval operations are implemented at an element-by-element level in the finite element framework. The numerical results for two structural-acoustic models verify the accuracy and effectiveness of the proposed methods.
Baizhan Xia - One of the best experts on this subject based on the ideXlab platform.
-
modified interval perturbation finite element method for a structural acoustic system with interval parameters
Journal of Applied Mechanics, 2013Co-Authors: Baizhan XiaAbstract:For the frequency response analysis of the structural-acoustic system with interval parameters, a modified interval perturbation finite element method (MIPFEM) is proposed. In the proposed method, the interval Dynamic Equilibrium Equation of the uncertain structural-acoustic system is established. The interval structural-acoustic Dynamic stiffness matrix and the interval force vector are expanded by using the first-order Taylor series; the inversion of the invertible interval structural-acoustic Dynamic stiffness matrix is approximated by employing a modified approximate interval-value Sherman–Morrison–Woodbury formula. The proposed method is implemented at an element-by-element level in the finite element framework. Numerical results on a shell structural-acoustic system with interval parameters verify the accuracy and efficiency of the proposed method.
-
probabilistic interval perturbation methods for hybrid uncertain acoustic field prediction
Journal of Vibration and Acoustics, 2013Co-Authors: Baizhan Xia, Jian LiuAbstract:For the hybrid uncertain acoustic field prediction with random and interval variables, the random interval Dynamic Equilibrium Equation is established and two hybrid probabilistic interval perturbation methods, named as hybrid perturbation Monte Carlo method (HPMCM) and hybrid perturbation vertex method (HPVM), are present. In HPMCM, the intervals of expectation and variance of sound pressure are calculated by a combination of the random interval matrix perturbation method, the random interval moment method and Monte Carlo method. In HPVM, the intervals of expectation and variance of sound pressure are calculated by a combination of the random interval matrix perturbation method, the random interval moment method and the vertex method. Numerical results on a 2D acoustic tube, the 2D acoustic cavity of a car and a 3D acoustic cavity verify the effectiveness and the high efficiency of HPVM when compared with HPMCM. HPVM can be considered as an effective engineering method to quantify the effects of parametric uncertainty on the sound pressure response.
-
Interval and subinterval perturbation methods for a structural-acoustic system with interval parameters
Journal of Fluids and Structures, 2013Co-Authors: Baizhan Xia, Jian LiuAbstract:Abstract Interval and subinterval perturbation methods have been widely applied in response analyses of the uncertain structure with interval parameters. In this paper, based on the characteristics of structural-acoustic systems, the interval and subinterval perturbation methods are extended to calculate the frequency response intervals of a structural-acoustic system with interval parameters. In the extended methods, the interval Dynamic Equilibrium Equation of the structural-acoustic system is established, and interval operations are implemented at an element-by-element level in the finite element framework. The numerical results for two structural-acoustic models verify the accuracy and effectiveness of the proposed methods.
Joao Manuel R S Tavares - One of the best experts on this subject based on the ideXlab platform.
-
physical simulation using fem modal analysis and the Dynamic Equilibrium Equation
CompIMAGE, 2006Co-Authors: Patricia C T Goncalves, Raquel Ramos Pinho, Joao Manuel R S TavaresAbstract:This paper presents a physical approach to simulate objects deformation in images. To physically model the given objects the finite element method is used, and to match the objects’ nodes modal analysis is considered. The desired displacement field is estimated through the Dynamic Equilibrium Equation. To solve this differential Equation different integration methods can be used. In this paper we present and discuss the results obtained using four numerical integration methods: central difference, Newmark’s and mode superposition allied with the former two. Some improvements are introduced in this work to allow the physical simulation even when not all of the objects nodes are successfully matched.
-
a physical simulation of objects behaviour by finite element method modal matching and Dynamic Equilibrium Equation
2004Co-Authors: Joao Manuel R S TavaresAbstract:This paper presents a physical approach to simulate image represented objects’ behaviour. The Finite Element Method (FEM) is employed to physically model the given objects, then modal analysis is used to match some objects’ nodes (by solving the related eigenvalue/vector problem and analysing each node displacement in the respective modal space (Sclaroff, Tavares)), and finally the Dynamic Equilibrium Equation is solved to estimate the object’s displacement field. To solve the Dynamic Equilibrium Equation different integration methods can be used, therefore the obtained results may differ. In this paper we briefly present the used approach and focus on the results obtained by three numerical integration methods: Central Difference, Newmark’s and Mode Superposition (Cook). The foremost method has first order precision, as the mass and stiffness matrixes are not diagonal and the damping effect is non-negligible, and we used an algorithm where the velocity is delayed in half time step. On the other hand, with Newmark’s method the Equation resolution can be unconditionally stable, with no numerical damping but with second order precision. The latter method was solved either with the Central Difference Method (usual algorithm used because the Mode Superposition transformed mass and stiffness matrixes are diagonal) or with Newmark’s Method. For an experimental result, we can consider the initial surface α represented in figure 1, obtained from a real pedobarography image (Tavares), and the target surface β in figure 2, obtained from α by applying a rigid transformation, with all nodes (124) successfully matched. With all mentioned integration methods, four intermediate shapes can be obtained: The Central Difference method’s last shape approaches the target surface in less than 700 pixels (which means than in average each node is less than 6 pixels away from its final position), figure 3. The closest approach of the target surface obtained by Newmark’s method is at 1600 pixels from β , figure 4. When the Mode Superposition method is used with 75% of the model’s modes, the Central Difference’s last shape is 1800 pixels from β , figure 5, while with the Newmark’s method is 1700 pixels, figure 6. Figure 1: Surface α . Figure 2: Surface β . Figure 3: Last shape obtained with Central Difference Method. Figure 4: ... with Newmark’s method. Figure 5: ... with Mode Superposition Method and Central Difference Method when 75% of the model’s modes are used. Figure 6: ... with Mode Superposition Method and Newmark’s method when 75% of the model’s modes
-
resolution of the Dynamic Equilibrium Equation to simulate objects movement deformation
2003Co-Authors: Raquel Ramos Pinho, Joao Manuel R S TavaresAbstract:The Dynamic Equilibrium Equation can be used between objects’ images to physically simulate their transformation. Given two images of the same object or images of different objects, a temporal estimation of the represented deformation can be made, according to the properties of the used virtual material and also attending to the applied charges on the built model. This methodology allows also the estimation of the local and global strain energy involved, which can be used to translate the existent transformation.
Xinzhi Wang - One of the best experts on this subject based on the ideXlab platform.
-
on the nonlinear vibration of heated corrugated circular plates with shallow sinusoidal corrugations
International Journal of Mechanical Sciences, 2008Co-Authors: Yonggang Wang, Xinzhi WangAbstract:Abstract The large amplitude free vibration of corrugated circular plates with shallow sinusoidal corrugations under uniformly static temperature changes is investigated. Based on the nonlinear bending theory of thin shallow shells, the governing Equations for corrugated plates are established from Hamilton's principle. These partial differential Equations are reduced to corresponding ordinary ones by elimination of the time variable with Kantorovich averaging method following an assumed harmonic time mode. Then by introducing the Green's function, the resulting Dynamic compatible Equation and corresponding boundary conditions are converted into equivalent integral Equations. Taking the central maximum amplitude of the plate as the perturbation parameter, the perturbation-variation method is used to Dynamic Equilibrium Equation with the aid of Computer Algebra Systems, Maple, from which, the third-order approximate characteristic relation of frequency vs. amplitude for nonlinear vibration of heated corrugated plates is obtained, and the frequency–amplitude characteristic curve is plotted for some specific values of temperature and geometrical parameters. It is found that the rise in temperature will decrease the frequency and vice versa. The nonlinear effect weakens when corrugations become deeper and dense. The present method can easily be expanded for the analysis of nonlinear vibration problem for other heated thin plates and shells.
Pengfei Jia - One of the best experts on this subject based on the ideXlab platform.
-
analysis on the Dynamic characteristic of a tensioned double beam system with a semi theoretical semi numerical method
Composite Structures, 2018Co-Authors: Han Fei, Dan Danhui, Wei Cheng, Pengfei JiaAbstract:Abstract In this study, the Dynamic characteristic of an inclined and tensioned double-beam system is investigated. The double-beam system consists of two elastic beams, which are quite different in mass and stiffness, and are continuously connected by a layer of elastic springs. The beam with larger stiffness and mass is under a tensile axial loading. The oscillatory differential Equations of this double-beam system are established by considering the effects of sag, flexural rigidity, boundary conditions, inclined angle of real inclined beams, and other factors simultaneously. Based on the governing Equations, the element transverse Dynamic stiffness matrix and global transverse Dynamic stiffness matrix are derived to obtain the Dynamic Equilibrium Equation of the system in a Dynamic stiffness form. Using this, the system is simplified into a four degree-of-freedom simple oscillatory system and consequently the theoretical frequency characteristic Equation is proposed for this double beam system. A numerical Equation rooting approach is developed to solve the Dynamical properties of the proposed Equation. With the numerical case studies, the Dynamic characteristics and its variation laws of a double-beam system are investigated. It shows that the proposed semi theoretical semi numerical methods can give an accurate solution for the double beam system, and rules revealed in this study are help for comprehending the Dynamical behavior of double beam like engineering structures theoretically.
