In this study,an iterative-based three-dimensional finite element lower bound in association with the second-order cone programming method is adopted to evaluate the limit load of a single pile embedded in cross-aniso...In this study,an iterative-based three-dimensional finite element lower bound in association with the second-order cone programming method is adopted to evaluate the limit load of a single pile embedded in cross-anisotropic soils under general loading condition.The lower bound solutions of the pile embedded in an anisotropic soil deposit can be found by formulating the element equilibrium,equilibrium of shear and normal stresses along discontinuities,boundary conditions,yield function,and optimizing the objective function through the second-order cone programming method in conjunction with an iterative-based update procedure.A general loading condition is considered to profile the expansion of the safe load in the vertical-horizontal-moment(V-H-M)space.The results of this study are compared and validated against three different cases including an isotropic lateral loading,anisotropic end bearing capacity,and a pile embedded in an isotropic soil deposit under general loading condition.A parametric study is conducted to evaluate the impact of different influencing factors.It was found that the effect of anisotropy on the variation of lateral limit load of a single pile is more pronounced than the corresponding vertical and bending moment limit loads,whereas the interface properties have more significant effects on the vertical and bending moment limit loads in comparison to the lateral limit load.展开更多
In this paper,the application of Abaqus-based particle finite element method(PFEM)is extended from static to dynamic large deformation.The PFEM is based on periodic mesh regeneration with Delaunay triangulation to avo...In this paper,the application of Abaqus-based particle finite element method(PFEM)is extended from static to dynamic large deformation.The PFEM is based on periodic mesh regeneration with Delaunay triangulation to avoid mesh distortion.Additional mesh smoothing and boundary node smoothing techniques are incorporated to improve the mesh quality and solution accuracy.The field variables are mapped from the old to the new mesh using the closest point projection method to minimize the mapping error.The procedures of the proposed Abaqus-based dynamic PFEM(Abaqus-DPFEM)analysis and its implementation in Abaqus are detailed.The accuracy and robustness of the proposed approach are examined via four illustrative numerical examples.The numerical results show a satisfactory agreement with published results and further confirm the applicability of the Abaqus-DPFEM to solving dynamic large-deformation problems in geotechnical engineering.展开更多
Rigid Finite Element Method (RFEM) was proposed to simulate the mechanical behavior of discontinuous structures such as rock and soil structures. The authors' work on the theory and applications of RFEM is summari...Rigid Finite Element Method (RFEM) was proposed to simulate the mechanical behavior of discontinuous structures such as rock and soil structures. The authors' work on the theory and applications of RFEM is summarized in this paper. Based on the theory of RFEM, the Elastic Body-Seams Model (EBSM) is proposed to take the deformation and damage of rock masses into account.展开更多
According to the lower-bound theorem of limit analysis the Rigid Finite Element Meth-od(RFEM)is applied to structural limit analysis and the linear programmings for limit analysis are deducedin this paper.Moreover,the...According to the lower-bound theorem of limit analysis the Rigid Finite Element Meth-od(RFEM)is applied to structural limit analysis and the linear programmings for limit analysis are deducedin this paper.Moreover,the Thermo-Parameter Method(TPM)and Parametric Variational principles(PVP)are used to reduce the computational effort while maintaining the accuracy of solutions.A better solution isalso obtained in this paper.展开更多
A new method of three-dimensional remeshing is proposed for rigid-plastic finiteelement analysis of a complicated forging process.The forging process of a cylindricalhousing has been simulated to show the effectivenes...A new method of three-dimensional remeshing is proposed for rigid-plastic finiteelement analysis of a complicated forging process.The forging process of a cylindricalhousing has been simulated to show the effectiveness of the scheme.The result ofsimulation shows that the computation can be effectively carried out by using the des-cribed remeshing scheme.展开更多
The effect of various process variables on the law of metal flow for semi-solid rolling 60Si2Mn was studied by finite element method. Semi-solid 60Si2Mn can be described as compressible rigid visco-plastic porous mate...The effect of various process variables on the law of metal flow for semi-solid rolling 60Si2Mn was studied by finite element method. Semi-solid 60Si2Mn can be described as compressible rigid visco-plastic porous material saturated with liquid. In terms of ther-mo-mechanical coupling condition, the distributions of stress, velocity and temperature were studied using software MARC. The simulation results show that the rigid visco-plastic model can accurately describe the semi-solid 60Si2Mn rolling process. The great deformation can achieve completely in view of low flow stress of semi-solid slurry.展开更多
The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/stra...The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.展开更多
Purpose: To analyse, and compare using finite element analysis, the biomechanical properties of the 1.7 mm miniplate fixation against 2 conventional fixation techniques (2.0 mm bi-cortical screws and 2.0 mm miniplate)...Purpose: To analyse, and compare using finite element analysis, the biomechanical properties of the 1.7 mm miniplate fixation against 2 conventional fixation techniques (2.0 mm bi-cortical screws and 2.0 mm miniplate) used in the mandibular sagittal split osteotomy. Methods: A 3-D virtual mandible model was constructed using images from CT scan. Sagittal split osteotomy was carried out virtually, and the fixation techniques were applied onto the model. 9 virtual models consisted of the 3 fixation techniques with mandibular movements of 3 mm setback, 3 mm advancement and 7 mm advancement were developed. Bite forces of 50, 75 and 100 N were applied for incisor bite simulation and 100, 200 and 300 N for molar biting force. Finite element analysis was carried out in Solidworks, and readings of stresses and displacement were recorded. Wilcoxon rank sum test was applied and P-value of 0.05 was set for statistical analysis. Results: In this manuscript the authors have compared 3 internal fixation techniques in mandibular sagittal split osteotomy. There was a statistically significant difference for both stress and displacement readings between the 1.7 mm miniplate, the 2.0 mm bi-cortical screws and the 2.0 mm miniplate for all mandibular movements. For the 1.7 mm miniplate vs 2.0 mm bi-cortical screws, the stress reading was (P = 3.063e-08, W = 314), and for displacement was (P = 5.811e-05, W = 282). For the 1.7 mm miniplate vs 2.0 mm miniplate, the stress reading was (P = 9.862e-4, W = 263) and for displacement was (2.05e-2, W = 235). Conclusion: The 1.7 mm miniplate has adequate strength to be used in mandibular sagittal split osteotomy, although statistically less rigid when compared to the conventional 2.0 mm miniplate and 2.0 mm bi-cortical screws, especially in larger movements.展开更多
Though the lengthened shrink-fit holder (LSFH) is widely applied in high speed milling of the parts characterized by deep cavities at present, its design and selection mainly depends on the experience and lacks a corr...Though the lengthened shrink-fit holder (LSFH) is widely applied in high speed milling of the parts characterized by deep cavities at present, its design and selection mainly depends on the experience and lacks a correct theoretical guidance. In this paper, attention is focus on the radial grip rigidity of the matching of LSFH and cutter in high speed milling. Based on the experiment modal analysis (EMA) technique, an accurate finite element model of the matching of LSFH and cutter is established firstly. Subsequently, the influence of different interference, grip length and spindle speed on the grip rigidity of LSFH are analyzed. The analysis results show that there is a reasonable interference and grip length between the LSFH and cutter so that to have a steepless grip and have a good radial grip rigidity and at the same time to avoid the strength of LSFH to exceed it’s yield limit which will reduce the precision and service life of LSFH, besides when spindle speed reach a extension the weakening influence of the centrifugal force on the radial grip rigidity of the matching of LSFH and cutter should been taken into account. Finally, the finite element analysis results are verified based on the construction of measurement method of the grip rigidity and the results fit very well. The studies provide a theoretical basis for the design, selection and the serialization and standardization of the matching of LSFH and cutter.展开更多
Flexible hinges are widely used in micro motion robotics. Its rigidity directly influences an organization's terminal localization. Its actual structure geometry size cannot satisfy the theoretical analysis completel...Flexible hinges are widely used in micro motion robotics. Its rigidity directly influences an organization's terminal localization. Its actual structure geometry size cannot satisfy the theoretical analysis completely in a theoretical supposition condition. In this paper, we analyzed the rotation rigidity of a corner-filleted straight beam flexible hinge in different parameters using finite element software ANSYS. The errors are discovered and compared with theoretical results. Through the graph of the flexible hinge parameters and its performance, an analysis of changes of parameters on the performance of a corner-filleted flexible hinge was carried out. The key manufacture parameters that affect the performance of a corner-filleted flexure hinge the most and rules of design are given, which can provide directions of design precision for the flexure hinge.展开更多
Basic assumptions are proposed for the continuity model of a tubular hollow slab combined with continuity analysis and calculation of a finite-element model;the continuity Equation of a tubular hollow slab at the mino...Basic assumptions are proposed for the continuity model of a tubular hollow slab combined with continuity analysis and calculation of a finite-element model;the continuity Equation of a tubular hollow slab at the minor axis supported at two ends of the hollow axle under a vertical even load is determined and solved. The overall equivalent flexural rigidity is then determined, which provides important conditions for the continuity analysis of tubular hollow floor supported along four sides.展开更多
This paper presents a numerical investigation on the structural performance of an innovative noise barrier consisting of poly-block, rigid polyurethane foam (RPF) and polyurea. The mechanical characteristics of RPF ...This paper presents a numerical investigation on the structural performance of an innovative noise barrier consisting of poly-block, rigid polyurethane foam (RPF) and polyurea. The mechanical characteristics of RPF as well as the flexural resistance of the proposed wall system (poly-wall) were established and presented in another study. The experimental results are used in the current study to develop, calibrate and verify 3D finite element (FE) models of the wall system. The components of the poly-wall including steel rebars, poly-blocks and RPF cores were simulated and then verified using the results of experiments conducted on the wall components. The results of numerical analysis exhibited a satisfactory agreement with the experimental outcomes for the entire wall system. The verified numerical models were then used to conduct a parametric study on the performance of poly-wall models under uniform wind load and gravity load. The findings of the current study confirmed that the structural performance of poly-wall is satisfactory for noise barrier application. Simulation techniques for improvement of the numerical analysis of multi-martial 3D FE models were discussed.展开更多
Taking double-die ironing for example, the plastic deformation behavior of theworkpiece in multidie ironing process is analysed by the rigid-plastic finite element method(RPFEM).Considering the strain hardening of the...Taking double-die ironing for example, the plastic deformation behavior of theworkpiece in multidie ironing process is analysed by the rigid-plastic finite element method(RPFEM).Considering the strain hardening of the material, the distrbutions of the effective strainrate and hydrostatic stress are obtained. Calculated results and the effect of die argles on thedeformation and ironing force are discussed. The companrson of calculated results with thcoe of ex-poriment shows a good agreement.展开更多
Wenchuan earthquake damage survey displayed the major structures of buildings suffered only small damages,but it was common that infill walls suffered heavy damages or even collapse. To study the failure forms and col...Wenchuan earthquake damage survey displayed the major structures of buildings suffered only small damages,but it was common that infill walls suffered heavy damages or even collapse. To study the failure forms and collapse mechanism of infill walls in an earthquake,the influence of opening or length-to-height ratio on shake-resisting capability of filling walls was analyzed,and measures to improve the anti-collapse ability of infill walls were put forwaed. The numerical simulations on collapse process in earthquake were carried out by using ABAQUS software. We used 5 single story and single span models. It is revealed that the rigidity and compressive capacity of infill walls are reduced because of the infill walls with holes and the increases of length-to-height ratios. Adding constructional columns and horizontal beams can ensure structural integrity and improve the anti-collapse ability of the wall.展开更多
Cohesive element is developed from the Dugdal-Barenblatt model in the field of fracture mechanics. The mechanical constitutive relation of cohesive element can be artificially assumed depending on the specific applica...Cohesive element is developed from the Dugdal-Barenblatt model in the field of fracture mechanics. The mechanical constitutive relation of cohesive element can be artificially assumed depending on the specific applications. It has been successfully applied in the study of crystal plasticity/brittle fracture process and decohesion between delaminations. In this paper, tensile experiments of large steel plate with different length of pre-existing cracks are conducted. Based on commercial software ABAQUS, cohesive element is adopted to simulate the tensile tests, and appropriate parameter values are obtained by fitting displacement-force curves. Using these parameters, a numerical method is presented by applying cohesive element to thermo-elastic-plastic finite element method (TEP-FEM) to simulate plate rigid restraint cracking (PRRC) tests. By changing constitutive relation of cohesive element, dimensions of the model and welding conditions, the influence of welding restraint intensity and welding conditions on the crack propagation are discussed, respectively. Three types of welding cold cracking are simulated. Significant influence of welding cold cracking on resistant stress in welding line is captured by this numerical method.展开更多
文摘In this study,an iterative-based three-dimensional finite element lower bound in association with the second-order cone programming method is adopted to evaluate the limit load of a single pile embedded in cross-anisotropic soils under general loading condition.The lower bound solutions of the pile embedded in an anisotropic soil deposit can be found by formulating the element equilibrium,equilibrium of shear and normal stresses along discontinuities,boundary conditions,yield function,and optimizing the objective function through the second-order cone programming method in conjunction with an iterative-based update procedure.A general loading condition is considered to profile the expansion of the safe load in the vertical-horizontal-moment(V-H-M)space.The results of this study are compared and validated against three different cases including an isotropic lateral loading,anisotropic end bearing capacity,and a pile embedded in an isotropic soil deposit under general loading condition.A parametric study is conducted to evaluate the impact of different influencing factors.It was found that the effect of anisotropy on the variation of lateral limit load of a single pile is more pronounced than the corresponding vertical and bending moment limit loads,whereas the interface properties have more significant effects on the vertical and bending moment limit loads in comparison to the lateral limit load.
基金the National Natural Science Foundation of China(Grant No.41807223)the Fundamental Research Funds for the Central Universities(Grant No.B210202096)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA 23090202).
文摘In this paper,the application of Abaqus-based particle finite element method(PFEM)is extended from static to dynamic large deformation.The PFEM is based on periodic mesh regeneration with Delaunay triangulation to avoid mesh distortion.Additional mesh smoothing and boundary node smoothing techniques are incorporated to improve the mesh quality and solution accuracy.The field variables are mapped from the old to the new mesh using the closest point projection method to minimize the mapping error.The procedures of the proposed Abaqus-based dynamic PFEM(Abaqus-DPFEM)analysis and its implementation in Abaqus are detailed.The accuracy and robustness of the proposed approach are examined via four illustrative numerical examples.The numerical results show a satisfactory agreement with published results and further confirm the applicability of the Abaqus-DPFEM to solving dynamic large-deformation problems in geotechnical engineering.
文摘Rigid Finite Element Method (RFEM) was proposed to simulate the mechanical behavior of discontinuous structures such as rock and soil structures. The authors' work on the theory and applications of RFEM is summarized in this paper. Based on the theory of RFEM, the Elastic Body-Seams Model (EBSM) is proposed to take the deformation and damage of rock masses into account.
基金The project supported by National Natural Science Foundation of China
文摘According to the lower-bound theorem of limit analysis the Rigid Finite Element Meth-od(RFEM)is applied to structural limit analysis and the linear programmings for limit analysis are deducedin this paper.Moreover,the Thermo-Parameter Method(TPM)and Parametric Variational principles(PVP)are used to reduce the computational effort while maintaining the accuracy of solutions.A better solution isalso obtained in this paper.
文摘A new method of three-dimensional remeshing is proposed for rigid-plastic finiteelement analysis of a complicated forging process.The forging process of a cylindricalhousing has been simulated to show the effectiveness of the scheme.The result ofsimulation shows that the computation can be effectively carried out by using the des-cribed remeshing scheme.
基金the National Natural Science Foundation of China (No.59995440).
文摘The effect of various process variables on the law of metal flow for semi-solid rolling 60Si2Mn was studied by finite element method. Semi-solid 60Si2Mn can be described as compressible rigid visco-plastic porous material saturated with liquid. In terms of ther-mo-mechanical coupling condition, the distributions of stress, velocity and temperature were studied using software MARC. The simulation results show that the rigid visco-plastic model can accurately describe the semi-solid 60Si2Mn rolling process. The great deformation can achieve completely in view of low flow stress of semi-solid slurry.
基金Project(50575143)supported by the National Natural Science Foundation of ChinaProject(20040248005)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.
文摘Purpose: To analyse, and compare using finite element analysis, the biomechanical properties of the 1.7 mm miniplate fixation against 2 conventional fixation techniques (2.0 mm bi-cortical screws and 2.0 mm miniplate) used in the mandibular sagittal split osteotomy. Methods: A 3-D virtual mandible model was constructed using images from CT scan. Sagittal split osteotomy was carried out virtually, and the fixation techniques were applied onto the model. 9 virtual models consisted of the 3 fixation techniques with mandibular movements of 3 mm setback, 3 mm advancement and 7 mm advancement were developed. Bite forces of 50, 75 and 100 N were applied for incisor bite simulation and 100, 200 and 300 N for molar biting force. Finite element analysis was carried out in Solidworks, and readings of stresses and displacement were recorded. Wilcoxon rank sum test was applied and P-value of 0.05 was set for statistical analysis. Results: In this manuscript the authors have compared 3 internal fixation techniques in mandibular sagittal split osteotomy. There was a statistically significant difference for both stress and displacement readings between the 1.7 mm miniplate, the 2.0 mm bi-cortical screws and the 2.0 mm miniplate for all mandibular movements. For the 1.7 mm miniplate vs 2.0 mm bi-cortical screws, the stress reading was (P = 3.063e-08, W = 314), and for displacement was (P = 5.811e-05, W = 282). For the 1.7 mm miniplate vs 2.0 mm miniplate, the stress reading was (P = 9.862e-4, W = 263) and for displacement was (2.05e-2, W = 235). Conclusion: The 1.7 mm miniplate has adequate strength to be used in mandibular sagittal split osteotomy, although statistically less rigid when compared to the conventional 2.0 mm miniplate and 2.0 mm bi-cortical screws, especially in larger movements.
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2009AA44302)Scientific Research Fund of Hunan Provincial Education Department, China (Grant No. 10C1259)+2 种基金Hunan Provincial Planned Science and Technology Project of China (Grant No. 2011FJ3231)National Natural Science Foundation of China (Grant No. 51005194)Open Innovation Platform of Hunan College Fund, China (Grant No. 10K063)
文摘Though the lengthened shrink-fit holder (LSFH) is widely applied in high speed milling of the parts characterized by deep cavities at present, its design and selection mainly depends on the experience and lacks a correct theoretical guidance. In this paper, attention is focus on the radial grip rigidity of the matching of LSFH and cutter in high speed milling. Based on the experiment modal analysis (EMA) technique, an accurate finite element model of the matching of LSFH and cutter is established firstly. Subsequently, the influence of different interference, grip length and spindle speed on the grip rigidity of LSFH are analyzed. The analysis results show that there is a reasonable interference and grip length between the LSFH and cutter so that to have a steepless grip and have a good radial grip rigidity and at the same time to avoid the strength of LSFH to exceed it’s yield limit which will reduce the precision and service life of LSFH, besides when spindle speed reach a extension the weakening influence of the centrifugal force on the radial grip rigidity of the matching of LSFH and cutter should been taken into account. Finally, the finite element analysis results are verified based on the construction of measurement method of the grip rigidity and the results fit very well. The studies provide a theoretical basis for the design, selection and the serialization and standardization of the matching of LSFH and cutter.
文摘Flexible hinges are widely used in micro motion robotics. Its rigidity directly influences an organization's terminal localization. Its actual structure geometry size cannot satisfy the theoretical analysis completely in a theoretical supposition condition. In this paper, we analyzed the rotation rigidity of a corner-filleted straight beam flexible hinge in different parameters using finite element software ANSYS. The errors are discovered and compared with theoretical results. Through the graph of the flexible hinge parameters and its performance, an analysis of changes of parameters on the performance of a corner-filleted flexible hinge was carried out. The key manufacture parameters that affect the performance of a corner-filleted flexure hinge the most and rules of design are given, which can provide directions of design precision for the flexure hinge.
文摘Basic assumptions are proposed for the continuity model of a tubular hollow slab combined with continuity analysis and calculation of a finite-element model;the continuity Equation of a tubular hollow slab at the minor axis supported at two ends of the hollow axle under a vertical even load is determined and solved. The overall equivalent flexural rigidity is then determined, which provides important conditions for the continuity analysis of tubular hollow floor supported along four sides.
文摘This paper presents a numerical investigation on the structural performance of an innovative noise barrier consisting of poly-block, rigid polyurethane foam (RPF) and polyurea. The mechanical characteristics of RPF as well as the flexural resistance of the proposed wall system (poly-wall) were established and presented in another study. The experimental results are used in the current study to develop, calibrate and verify 3D finite element (FE) models of the wall system. The components of the poly-wall including steel rebars, poly-blocks and RPF cores were simulated and then verified using the results of experiments conducted on the wall components. The results of numerical analysis exhibited a satisfactory agreement with the experimental outcomes for the entire wall system. The verified numerical models were then used to conduct a parametric study on the performance of poly-wall models under uniform wind load and gravity load. The findings of the current study confirmed that the structural performance of poly-wall is satisfactory for noise barrier application. Simulation techniques for improvement of the numerical analysis of multi-martial 3D FE models were discussed.
文摘Taking double-die ironing for example, the plastic deformation behavior of theworkpiece in multidie ironing process is analysed by the rigid-plastic finite element method(RPFEM).Considering the strain hardening of the material, the distrbutions of the effective strainrate and hydrostatic stress are obtained. Calculated results and the effect of die argles on thedeformation and ironing force are discussed. The companrson of calculated results with thcoe of ex-poriment shows a good agreement.
基金Funded by research programs in Jiangsu(JGJH2008-22)
文摘Wenchuan earthquake damage survey displayed the major structures of buildings suffered only small damages,but it was common that infill walls suffered heavy damages or even collapse. To study the failure forms and collapse mechanism of infill walls in an earthquake,the influence of opening or length-to-height ratio on shake-resisting capability of filling walls was analyzed,and measures to improve the anti-collapse ability of infill walls were put forwaed. The numerical simulations on collapse process in earthquake were carried out by using ABAQUS software. We used 5 single story and single span models. It is revealed that the rigidity and compressive capacity of infill walls are reduced because of the infill walls with holes and the increases of length-to-height ratios. Adding constructional columns and horizontal beams can ensure structural integrity and improve the anti-collapse ability of the wall.
文摘Cohesive element is developed from the Dugdal-Barenblatt model in the field of fracture mechanics. The mechanical constitutive relation of cohesive element can be artificially assumed depending on the specific applications. It has been successfully applied in the study of crystal plasticity/brittle fracture process and decohesion between delaminations. In this paper, tensile experiments of large steel plate with different length of pre-existing cracks are conducted. Based on commercial software ABAQUS, cohesive element is adopted to simulate the tensile tests, and appropriate parameter values are obtained by fitting displacement-force curves. Using these parameters, a numerical method is presented by applying cohesive element to thermo-elastic-plastic finite element method (TEP-FEM) to simulate plate rigid restraint cracking (PRRC) tests. By changing constitutive relation of cohesive element, dimensions of the model and welding conditions, the influence of welding restraint intensity and welding conditions on the crack propagation are discussed, respectively. Three types of welding cold cracking are simulated. Significant influence of welding cold cracking on resistant stress in welding line is captured by this numerical method.