The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed w...The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed with innovative types of smoothing domains. These models are found having a number of important and theoretically profound properties. This article first provides a concise and easy-to-follow presentation of key formulations used in the S-FEM. A number of important properties and unique features of S-FEM models are discussed in detail, including 1) theoretically proven softening effects;2) upper-bound solutions;3) accurate solutions and higher convergence rates;4) insensitivity to mesh distortion;5) Jacobian?free;6) volumetric-locking-free;and most importantly 7) working well with triangular and tetrahedral meshes that can be automatically generated. The S-FEM is thus ideal for automation in computations and adaptive analyses, and hence has profound impact on Al-assisted modeling and simulation. Most importantly, one can now purposely design an S-FEM model to obtain solutions with special properties as wish, meaning that S-FEM offers a framework for design numerical models with desired properties. This novel concept of numerical model demand may drastically change the landscape of modeling and simulation. Future directions of research are also provided.展开更多
Abstract Recently, pH-sensitive hydrogels have been utilized in the diverse applications including sensors, switches, and actuators. In order to have continuous stress and defor- mation fields, a new semi-analytical a...Abstract Recently, pH-sensitive hydrogels have been utilized in the diverse applications including sensors, switches, and actuators. In order to have continuous stress and defor- mation fields, a new semi-analytical approach is developed to predict the swelling induced finite bending for a functionally graded (FG) layer composed of a pH-sensitive hydrogel, in which the cross-link density is continuously distributed along the thickness direction under the plane strain condition. Without considering the intermediary virtual reference, the initial state is mapped into the deformed configuration in a circular shape by utilizing a total deformation gradient tensor stemming from the inhomogeneous swelling of an FG layer in response to the variation of the pH value of the solvent. To enlighten the capabil- ity of the presented analytical method, the finite element method (FEM) is used to verify the accuracy of the analytical results in some case studies. The perfect agreement con- firms the accuracy of the presented method. Due to the applicability of FG pH-sensitive hydrogels, some design factors such as the semi-angle, the bending curvature, the aspect ratio, and the distributions of deformation and stress fields are studied. Furthermore, the tangential free-stress axes are illustrated in deformed configuration.展开更多
Homogenization is a promising approach to capture the behavior of complex structures like corrugated panels. It enables us to replace high-cost shell models with stiffness-equivalent orthotropic plate alternatives. Ma...Homogenization is a promising approach to capture the behavior of complex structures like corrugated panels. It enables us to replace high-cost shell models with stiffness-equivalent orthotropic plate alternatives. Many homogenization models for corrugated panels of different shapes have been proposed. However, there is a lack of investigations for verifying their accuracy and reliability. In addition, in the recent trend of development of smoothed finite element methods, the cell-based smoothed three-node Mindlin plate element (CS-MIN3) based on the first-order shear deformation theory (FSDT) has been proposed and successfully applied to many analyses of plate and shell structures. Thus, this paper further extends the CS-MIN3 by integrating itself with homogenization models to give homogenization methods. In these methods, the equivalent extensional, bending, and transverse shear stiftriess components which constitute the equivalent orthotropic plate models are represented in explicit analytical expressions. Using the results of ANSYS and ABAQUS shell simulations as references, some numerical examples are conducted to verify the accuracy and reliability of the homogenization methods for static analyses of trapezoidally and sinusoidally corrugated panels.展开更多
The hypercompressor is one of the core facilities in low density polyethylene production,with a discharge pressure of approximately 300 MPa.A packing cup is the basic unit of cylinder packing,assembled by the interfer...The hypercompressor is one of the core facilities in low density polyethylene production,with a discharge pressure of approximately 300 MPa.A packing cup is the basic unit of cylinder packing,assembled by the interference fit between an inner cup and an outer cup.Because the shrink-fitting prestresses the packing cup,serious design is needed to gain a favorable stress state,for example,a tri-axial compressive stress state.The traditional method of designing the interference fit value for packing cups depends on the shrink-fit theory for thickwalled cylinder subject to internal and external pressure.According to the traditional method,critical points are at the inner radii of the inner and external cup.In this study,the finite element method(FEM)has been implementcd to determine a more accurate stress level of packing cups.Different critical points have been found at the edge of lapped sealing surfaces between two adjacent packing cups.The maximum Von Mises equivalent stress in a packing cup increases after a decline with the rise of the interference fit value.The maximum equivalent stress initially occurs at the bore of the inner cup,then at the edge of lapped mating surfaces,and finally at the bore of the outer cup,as the interference radius increases.The traditional method neglects the influence of axial preloading on the interference mating pressure.As a result,it predicts a lower equivalent stress at the bore of the external cup.A higher interference fit value accepted by the traditional method may not be feasible as it might already make packing cups yield at the edge of mating surfaces or the bore of the external cup.Along with fatigue analysis,the feasible range of interference fit value has been modified by utilizing FEM.The modified range tends to be narrower and safer than the one derived from the traditional method,after getting rid of shrink-fit values that could result in yielding in a real packing cup.展开更多
文摘The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed with innovative types of smoothing domains. These models are found having a number of important and theoretically profound properties. This article first provides a concise and easy-to-follow presentation of key formulations used in the S-FEM. A number of important properties and unique features of S-FEM models are discussed in detail, including 1) theoretically proven softening effects;2) upper-bound solutions;3) accurate solutions and higher convergence rates;4) insensitivity to mesh distortion;5) Jacobian?free;6) volumetric-locking-free;and most importantly 7) working well with triangular and tetrahedral meshes that can be automatically generated. The S-FEM is thus ideal for automation in computations and adaptive analyses, and hence has profound impact on Al-assisted modeling and simulation. Most importantly, one can now purposely design an S-FEM model to obtain solutions with special properties as wish, meaning that S-FEM offers a framework for design numerical models with desired properties. This novel concept of numerical model demand may drastically change the landscape of modeling and simulation. Future directions of research are also provided.
文摘Abstract Recently, pH-sensitive hydrogels have been utilized in the diverse applications including sensors, switches, and actuators. In order to have continuous stress and defor- mation fields, a new semi-analytical approach is developed to predict the swelling induced finite bending for a functionally graded (FG) layer composed of a pH-sensitive hydrogel, in which the cross-link density is continuously distributed along the thickness direction under the plane strain condition. Without considering the intermediary virtual reference, the initial state is mapped into the deformed configuration in a circular shape by utilizing a total deformation gradient tensor stemming from the inhomogeneous swelling of an FG layer in response to the variation of the pH value of the solvent. To enlighten the capabil- ity of the presented analytical method, the finite element method (FEM) is used to verify the accuracy of the analytical results in some case studies. The perfect agreement con- firms the accuracy of the presented method. Due to the applicability of FG pH-sensitive hydrogels, some design factors such as the semi-angle, the bending curvature, the aspect ratio, and the distributions of deformation and stress fields are studied. Furthermore, the tangential free-stress axes are illustrated in deformed configuration.
基金the University of Science,Vietnam National University Hochiminh City (VNU-HCM) under grant number T2015-3.
文摘Homogenization is a promising approach to capture the behavior of complex structures like corrugated panels. It enables us to replace high-cost shell models with stiffness-equivalent orthotropic plate alternatives. Many homogenization models for corrugated panels of different shapes have been proposed. However, there is a lack of investigations for verifying their accuracy and reliability. In addition, in the recent trend of development of smoothed finite element methods, the cell-based smoothed three-node Mindlin plate element (CS-MIN3) based on the first-order shear deformation theory (FSDT) has been proposed and successfully applied to many analyses of plate and shell structures. Thus, this paper further extends the CS-MIN3 by integrating itself with homogenization models to give homogenization methods. In these methods, the equivalent extensional, bending, and transverse shear stiftriess components which constitute the equivalent orthotropic plate models are represented in explicit analytical expressions. Using the results of ANSYS and ABAQUS shell simulations as references, some numerical examples are conducted to verify the accuracy and reliability of the homogenization methods for static analyses of trapezoidally and sinusoidally corrugated panels.
文摘The hypercompressor is one of the core facilities in low density polyethylene production,with a discharge pressure of approximately 300 MPa.A packing cup is the basic unit of cylinder packing,assembled by the interference fit between an inner cup and an outer cup.Because the shrink-fitting prestresses the packing cup,serious design is needed to gain a favorable stress state,for example,a tri-axial compressive stress state.The traditional method of designing the interference fit value for packing cups depends on the shrink-fit theory for thickwalled cylinder subject to internal and external pressure.According to the traditional method,critical points are at the inner radii of the inner and external cup.In this study,the finite element method(FEM)has been implementcd to determine a more accurate stress level of packing cups.Different critical points have been found at the edge of lapped sealing surfaces between two adjacent packing cups.The maximum Von Mises equivalent stress in a packing cup increases after a decline with the rise of the interference fit value.The maximum equivalent stress initially occurs at the bore of the inner cup,then at the edge of lapped mating surfaces,and finally at the bore of the outer cup,as the interference radius increases.The traditional method neglects the influence of axial preloading on the interference mating pressure.As a result,it predicts a lower equivalent stress at the bore of the external cup.A higher interference fit value accepted by the traditional method may not be feasible as it might already make packing cups yield at the edge of mating surfaces or the bore of the external cup.Along with fatigue analysis,the feasible range of interference fit value has been modified by utilizing FEM.The modified range tends to be narrower and safer than the one derived from the traditional method,after getting rid of shrink-fit values that could result in yielding in a real packing cup.
