A new method of elastic articulated objects (human bodies) modeling was presented based on a new conic curve. The model includes 3D object deformable curves which can represent the deformation of human occluding conto...A new method of elastic articulated objects (human bodies) modeling was presented based on a new conic curve. The model includes 3D object deformable curves which can represent the deformation of human occluding contours. The deformation of human occluding contour can be represented by adjusting only four deformation parameters for each limb. Then, the 3D deformation parameters are determined by corresponding 2D contours from a sequence of stereo images. The algorithm presented in this paper includes deformable conic curve parameters determination and the plane, 3D conic curve lying on, parameter determination.展开更多
Thermal effects are incorporated into developed discrete layer mechanics for two-dimensional cylindrical shells structures. Finite element equations are developed according to layerwise theory of laminated structure. ...Thermal effects are incorporated into developed discrete layer mechanics for two-dimensional cylindrical shells structures. Finite element equations are developed according to layerwise theory of laminated structure. Following the layerwise theory, a variable kinematic model that incorporates mechanics and thermal conditions is also presented. The new element has a field of displacement compatible with the cylindrical shell element or plate and it can be used as a rigid element for this structural element.ln the laminate model construction, adjacent layers are arranged as bonded layers. The layer has a unique constant thickness that can be different to each layer. The fiber reinforced is used and the fibers in a laminate may be oriented arbitrarily. The shear stress is adopted equal to zero because the thin thickness, on the other hand, the normal stress is maintained in order to ensure the compatibility of stress in material. The previously authors of this methods neglect the implications of thermal effects on cylindrical shells structures. Thermal effects become important when the structure has to operate in either extremely hot or cold temperature environments. These extreme conditions may severely affect the response of structure in two distinct ways： （1） induction of thermal stresses due to differences in the coefficients of thermal expansion between the various composite plies and layers and （2） temperature dependence of the elastic properties. Only a limited amount of work has been reported concerning this topic. All in all, the main contribution of this work is the consideration of this kinematic for cylindrical shells that incorporate mechanics and thermal conditions. In addition, numerical results are presented to demonstrate the capability of the current formulation to represent the behavior of cylindrical shells with these characteristics.展开更多
In this paper,a CFD/CSD model coupling N-S equations and structural equations of motion in the time domain is described for aeroelastic analysis of large wind turbines.The structural modes of blades are analyzed with ...In this paper,a CFD/CSD model coupling N-S equations and structural equations of motion in the time domain is described for aeroelastic analysis of large wind turbines.The structural modes of blades are analyzed with one-dimensional beam models.By combining point matched sliding grid for wind turbine rotation and deforming grid for structural vibrations,a hybrid dynamic grid strategy is designed for the multi-block structured grid system of a wind turbine.The dual time-stepping approach and finite volume scheme are applied to the three-dimensional unsteady preconditioned N-S equations,and DES approach is employed to simulate the unsteady massively separated flows.A modal approach is adopted to calculate the structural response,and a predictor-corrector scheme is used to solve the structural equations of motion.CFD and CSD solvers are tightly coupled via successive iterations within each physical time step.As a result,a time-domain CFD/CSD model for aeroelastic analysis of a large wind turbine is achieved.The presented method is applied to the NH1500 large wind turbine under the rated condition,and the calculated aeroelastic characteristics agree well with those of the prescribed vortex wake method.展开更多
基金the Postdoctoral Science Foundation of China(Grant No.20070421018)
文摘A new method of elastic articulated objects (human bodies) modeling was presented based on a new conic curve. The model includes 3D object deformable curves which can represent the deformation of human occluding contours. The deformation of human occluding contour can be represented by adjusting only four deformation parameters for each limb. Then, the 3D deformation parameters are determined by corresponding 2D contours from a sequence of stereo images. The algorithm presented in this paper includes deformable conic curve parameters determination and the plane, 3D conic curve lying on, parameter determination.
文摘Thermal effects are incorporated into developed discrete layer mechanics for two-dimensional cylindrical shells structures. Finite element equations are developed according to layerwise theory of laminated structure. Following the layerwise theory, a variable kinematic model that incorporates mechanics and thermal conditions is also presented. The new element has a field of displacement compatible with the cylindrical shell element or plate and it can be used as a rigid element for this structural element.ln the laminate model construction, adjacent layers are arranged as bonded layers. The layer has a unique constant thickness that can be different to each layer. The fiber reinforced is used and the fibers in a laminate may be oriented arbitrarily. The shear stress is adopted equal to zero because the thin thickness, on the other hand, the normal stress is maintained in order to ensure the compatibility of stress in material. The previously authors of this methods neglect the implications of thermal effects on cylindrical shells structures. Thermal effects become important when the structure has to operate in either extremely hot or cold temperature environments. These extreme conditions may severely affect the response of structure in two distinct ways： （1） induction of thermal stresses due to differences in the coefficients of thermal expansion between the various composite plies and layers and （2） temperature dependence of the elastic properties. Only a limited amount of work has been reported concerning this topic. All in all, the main contribution of this work is the consideration of this kinematic for cylindrical shells that incorporate mechanics and thermal conditions. In addition, numerical results are presented to demonstrate the capability of the current formulation to represent the behavior of cylindrical shells with these characteristics.
基金supported by the National Basic Research Program of China ("973" Project) (Grant No. 2007CB714600)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘In this paper,a CFD/CSD model coupling N-S equations and structural equations of motion in the time domain is described for aeroelastic analysis of large wind turbines.The structural modes of blades are analyzed with one-dimensional beam models.By combining point matched sliding grid for wind turbine rotation and deforming grid for structural vibrations,a hybrid dynamic grid strategy is designed for the multi-block structured grid system of a wind turbine.The dual time-stepping approach and finite volume scheme are applied to the three-dimensional unsteady preconditioned N-S equations,and DES approach is employed to simulate the unsteady massively separated flows.A modal approach is adopted to calculate the structural response,and a predictor-corrector scheme is used to solve the structural equations of motion.CFD and CSD solvers are tightly coupled via successive iterations within each physical time step.As a result,a time-domain CFD/CSD model for aeroelastic analysis of a large wind turbine is achieved.The presented method is applied to the NH1500 large wind turbine under the rated condition,and the calculated aeroelastic characteristics agree well with those of the prescribed vortex wake method.
