A new type of steel moment resisting frame with bottom flange friction devices (BFFDs) has been developed to provide self-centering capacity and energy dissipation, and to reduce permanent deformations under earthqu...A new type of steel moment resisting frame with bottom flange friction devices (BFFDs) has been developed to provide self-centering capacity and energy dissipation, and to reduce permanent deformations under earthquakes. This paper presents a numerical simulation of self-centering beam-column connections with BFFDs, in which the gap opening/closing at the beam-column interfaces is simulated by using pairs of zero-length elements with compression-only material properties, and the energy dissipation due to friction is simulated by using truss elements with specified hysteretic behavior. In particular, the effect of the friction bolt bearing against the slotted plate in the BFFDs was modeled, so that the increase in lateral force and the loss of friction force due to the bolt bearing could be taken into account. Parallel elastic-perfectly plastic gap (ElasticPPGap) materials in the Open System for Earthquake Engineering Simulation (OpenSees) were used with predefined gaps to specify the sequence that each bolt went into the bearing and the corresponding increase in bending stiffness. The MinMax material in OpenSees is used to specify the minimum and maximum values of strains of the ElasticPPGap materials. To consider the loss of friction force due to bok bearing, a number of parallel hysteretic materials were used, and the failure of these materials in sequence simulated the gradual loss of friction force. Analysis results obtained by using the proposed numerical model are discussed and compared with the test results under cyclic loadings and the seismic loading, respectively.展开更多
Double?roller clamping spinning(DRCS) is a new process for forming a thin?walled cylinder with a complex surface flange. The process requires a small spinning force,and can visibly improve forming quality and producti...Double?roller clamping spinning(DRCS) is a new process for forming a thin?walled cylinder with a complex surface flange. The process requires a small spinning force,and can visibly improve forming quality and production e ciency. However,the deformation mechanism of the process has not been completely understood. Therefore,both a finite element numerical simulation and experimental research on the DRCS process are carried out. The results show that both radial force and axial force dominate the forming process of DRCS. The deformation area elongates along the radial direction and bends along the axial direction under the action of the two forces. Both the outer edge and round corner of the flange show the tangential tensile stress and radial compressive stress. The middle region shows tensile tangential stress and radial stress,while the inner edge shows compressive tangential stress and radial stress. Tan?gential tensile strain causes a wall thickness reduction in the outer edge and middle regions of the flange. The large compressive thickness strain causes material accumulation and thus,an increase in the wall thickness of the round corner. Because of bending deformation,the round corner shows a large radial tensile strain in addition. The inner edge of the flange shows small radial compressive strain and tensile strain in thickness. Thus,the wall thickness on the inner edge of the flange continues to increase,although the increment is small. Furthermore,microstructure analysis and tensile test results show that the flanged thin?walled cylinder formed by DRCS has good mechanical properties. The results provide instructions for the application of the DRCS process.展开更多
Flange earrings of strong anisotropic sheet metals in deep-drawing process are numerically analyzed by the elastic-plastic large deformation finite element formulation based on a discrete Kirchhoff triangle plate shel...Flange earrings of strong anisotropic sheet metals in deep-drawing process are numerically analyzed by the elastic-plastic large deformation finite element formulation based on a discrete Kirchhoff triangle plate shell element model. A Barlat-Lian anisotropic yield function and a quasi-flow corner theory are used in the present formulation. The numerical results are compared with the experimental ones of cylindrical cup drawing process. The focus of the present researches is on the numerical analysis and the constraining scheme of the flange earring of circular sheets with strong anisotropy in square cup drawing process.展开更多
Carbonic composite materials and ceramics appear to be excellent structural materials for parts subjected to very high temperatures in molten salt reactors(MSRs), in which the reactor core outlet temperature is normal...Carbonic composite materials and ceramics appear to be excellent structural materials for parts subjected to very high temperatures in molten salt reactors(MSRs), in which the reactor core outlet temperature is normally above 700℃. Because of the high temperature,there are major challenges in the sealing of flanged connections for tubes made of alloys and nonmetallic materials. In this study, an improved method for sealing bolted flange connections for tubes made of dissimilar materials at high temperature is analyzed. The study focuses on the compensation mechanism for the difference in thermal expansion between the bolts and the flanges. An angle is introduced for the sealing surface in the flanged connection to provide effective sealing. The arctangent of the angle is the ratio of the thickness between the theoretical core of the sealing surface and the outside end face of the flange to the distances between the axis of the flanged joint and the theoretical core of the sealing surface of the flange; the sealing surface of the flange, which is made of the same material as the fastening assemblies, faces the fastening assemblies. To ensure effective sealing, the frictional coefficient between the two sealing surfaces should not exceed the tangent of the angle. This result does not agree well with the solution given by previous researchers. Further, in the modified flanged connection, the compression of each bolt in the clamped condition is increased to maintain the compaction force unchanged without increasing the number of bolts on the flanged joint.展开更多
The wind turbine with a flanged-diffuser shroud—so called “wind-lens turbine”—is developed as one of high performance wind turbines by Ohya et al. In this paper, the wind turbine performance is investigated for bo...The wind turbine with a flanged-diffuser shroud—so called “wind-lens turbine”—is developed as one of high performance wind turbines by Ohya et al. In this paper, the wind turbine performance is investigated for both steady and unsteady winds. The compact-type wind lens turbine shows higher efficiency than the only rotor wind turbine. Also, the flow structure around the compact-type wind turbine is made clear by CFD and PIV in steady wind. Furthermore, the performances of the only rotor and the compact-type wind-lens turbines for unsteady wind are experimentally and numerically investigated. Experimental and numerical results are presented to demonstrate the dependence of frequency of the harmonic oscillating velocity wind on power coefficient. Consequently, the compact-type wind-lens turbine show better performance than the only rotor one in sinusoidally oscillating velocity wind. Furthermore, the numerical estimation can predict the power coefficient in the oscillating flows to an accuracy of 94% to 102%. In addition, the dependence of the turbine performance on turbulent intensity and vortex scale of natural fluctuating wind is presented.展开更多
A new method for the determination of effective flange width under uniform load on simply supported box girder bridges considering shear lag effect is proposed in this paper. Based on the Symplectic Elasticity method,...A new method for the determination of effective flange width under uniform load on simply supported box girder bridges considering shear lag effect is proposed in this paper. Based on the Symplectic Elasticity method, the flange slab of the box girder is simplified into a plane stress plate. Using equilibrium conditions of the plates, the Hamilton dual equations for top plate element is established. The analytical formulas of each plate element considering shear lag effect are derived. The closed polynomial effective width expression of flange slab under uniform load on the whole span length has been obtained. Through examples using the finite element method, the results obtained by the proposed method are examined and the accuracy of the proposed method is verified.展开更多
This study was conducted to investigate the maxillary denture bases and occlusal discrepancies using the Vertex Thermosens in comparison with the conventional polymethyl-methacrylate materials. Twenty maxillary dentur...This study was conducted to investigate the maxillary denture bases and occlusal discrepancies using the Vertex Thermosens in comparison with the conventional polymethyl-methacrylate materials. Twenty maxillary denture bases were prepared from the Vertex ThermoSens and a conventional heat-cured denture base materials. Acrylic maxillary second molars were arranged in their respective positions on the ridge. After curing of both types of denture bases, they were deflasked with their respective master casts. Reference points were prepared for measurements of the antero-posterior and cross-arch dimensions at the denture borders using caliper device. Furthermore, the teeth discrepancies were measured between reference points in the ligual aspect of the second maxillary molars. The recorded data was analyzed using SPSS statistical software version 20. The results showed initial shrinkage of both denture bases in the antero-posterior and cross-arch dimensions immediately after decasting. This contraction was compensated gradually during storage in water up to 2 weeks. Regarding the variable time, there was a significant difference between the tested materials. Moreover, the results revealed occlusal discrepancies and shifting of teeth inward immediately after decasting, followed by outward movement after storage in water for 2 weeks. Regarding the variables time and materials, there were significant differences. Both materials exhibited inward shrinkage in the antero-posterior and cross-arch dimensions immediately after decasting. Both denture bases showed inward shifting of teeth immediately after decasting, followed by outward movement after storage in water up to 2 weeks.展开更多
The Hill's quadric anisotropy yield function and the Barlat-Lian anisotropy yield func- tion describing well anisotropy sheet metal with stronger texture are introduced into a quadric-flow cor- ner constitutive th...The Hill's quadric anisotropy yield function and the Barlat-Lian anisotropy yield func- tion describing well anisotropy sheet metal with stronger texture are introduced into a quadric-flow cor- ner constitutive theory of elastic-plastic finite deformation suitable for deformation localization analy- sis.And then,the elastic-plastic large deformation finite element formulation based on the virtual power principle and the discrete Kirchhoff shell element model including the yield functions and the constitutive theory are established.The focus of the present research is on the numerical simulation of the flange earing of the deep-drawing of anisotropy circular sheets,based on the investigated results, the.schemes for controlling the flange earing are proposed.展开更多
The hollow flange beam(HFB) is a unique cold-formed steel section developed in Australia for use as a flexural member.It′s a particular cross section with two torsion rigid closed triangular flanges and a comparative...The hollow flange beam(HFB) is a unique cold-formed steel section developed in Australia for use as a flexural member.It′s a particular cross section with two torsion rigid closed triangular flanges and a comparatively flexible web,and it is a type of high efficient cross section.This paper presents two kinds of new cold-formed flange-closed welding sections named HF1 and HF2 according to different section component and parameters of HFB.Nonlinear finite element method has been adopted to investigate the mechanical properties such as buckling mode,deformation process,rigidity,ductility and correlation curve of two kinds of new section members which being subjected to axial compression,flexure,combined compression and bending.Systematical comparisons of the consumed steel quantities of per unit load carrying capacity between new section members and the same section dimensions of cold-formed C-section members have been carried out.Some conclusions can be drawn from above work that the new sections have some superior properties including higher load carrying capacity and section modulus,sufficient section stiffness,and difficult occurrence for the sub element local buckling.The new sections are suitable for bearing flexure,compression,combined compression and bending.The new sections′ consumed steel quantities of per unit load carrying capacity are almost half as those of the same dimension C-section members′.The experimental investigation is carried out further on the new cold-formed flange-closed welding section members and can be used in the practical engineering.展开更多
FEM is used to analyze the influence of interface friction on the material flow and the cause of forming defect in the cold upsetting of tube flange. Based on the FEM simulation results, the relationships between flan...FEM is used to analyze the influence of interface friction on the material flow and the cause of forming defect in the cold upsetting of tube flange. Based on the FEM simulation results, the relationships between flange width and the extreme friction factors are established. The concept of forming limit diagram for cold upsetting of tube flange is presented.展开更多
This study covers optimization of I-sectional flange beams. Scope of this study is limited to medium weight flange beams of Table 1 of IS 808:1983 but it can be further extended for the other sections of this code. Be...This study covers optimization of I-sectional flange beams. Scope of this study is limited to medium weight flange beams of Table 1 of IS 808:1983 but it can be further extended for the other sections of this code. Best possible geometric shape of the cross-section is found for maximum performance of the beam with minimum material consumption. All possible loading conditions are considered in the study for which a beam in flexure undergoes in its life. ANSYS software program is used for the analysis and optimizing the sections. It is found that sections MB 125, MB 300 and MB 400 of Table 1 of IS 808 are not the optimum sections but other alternative of these cross-sections is available which within the same material consumption performs better than these sections of IS code.展开更多
Compared with general circular flanges, flanges on conical shells have different configurations. In the Chinese national code GBISO, however, there are no related contents about flange design of this kind of type. So,...Compared with general circular flanges, flanges on conical shells have different configurations. In the Chinese national code GBISO, however, there are no related contents about flange design of this kind of type. So, it needs to study loads of flanges of this kind of type. This paper takes the flange connection of a wide angle diffuser in a transonic and supersonic wind tunnel as the background, according to the principles of flange design in Chinese national code GB150, combining the characteristics of flanges of a wide angle diffuser, the loads of flanges have been analyzed, and the equations of loads and their locations have been presented.展开更多
In this paper,a failure evaluation criterion was proposed for the bolted casing-flange structure under impact loading.Subsequently,ballistic tests with eighteen bolted casing-flange structure specimens were conducted ...In this paper,a failure evaluation criterion was proposed for the bolted casing-flange structure under impact loading.Subsequently,ballistic tests with eighteen bolted casing-flange structure specimens were conducted to validate the failure evaluation criterion.Parameter studies were then carried out using the validated FE models.Both the experimental and numerical results demonstrated the accuracy of the failure evaluation criterion.The failure evaluation criterion provided a quick and easy way to determine the failure mode of the casing connection area by using the materials and dimensions of the structure.Based on the failure evaluation criterion,designing the structural failure mode of the bolted casing-flange structure to be between flange failure and bolt failure can improve the impact resistance of the connection area of the aero-engine casings.This investigation revealed that the impact failure is not the unique criterion in evaluating the containment of the casing connection area,structural failure should also be involved in the evaluation criteria.展开更多
Flange joint part is the weak link of wind turbine tower.In view of the special structure,complex stress and easy failure of the connecting bolt of the wind turbine tower flange,the relationship between the external l...Flange joint part is the weak link of wind turbine tower.In view of the special structure,complex stress and easy failure of the connecting bolt of the wind turbine tower flange,the relationship between the external load of the tower section and the internal stress of the bolt is established by the finite element method,and the time series internal stress of the bolt is calculated by the Schmidt-Neuper algorithm.The S-N curve which is suitable for the connecting bolt material of the tower flange is selected by the GL2010 specification.On the basis of Miner’s fatigue cumulative damage theory and rain flow counting method,the fatigue strength of the whole ring bolt is roughly calculated,and the most dangerous part is determined.The axial symmetry model of screw connection is used for accurately calculating the fatigue cumulative damage of the bolt at the dangerous part.The results show that the fatigue life of the bolts in the most dangerous position can meet the requirements,the engineering algorithm has advantages in determining the dangerous part of the whole ring bolt,and the finite element method has high accuracy in predicting the fatigue life of the bolts in the dangerous part.The proposed method is feasible and effective in predicting the fatigue life of the flange joint bolts of the tower.展开更多
The heat transfer characteristics of feedthrough flange under high alternating current excitation were investigated by threedimensional finite element model.The correlations between the heat transfer behaviors and sys...The heat transfer characteristics of feedthrough flange under high alternating current excitation were investigated by threedimensional finite element model.The correlations between the heat transfer behaviors and system parameters including applied current,ceramic thickness and working time were discussed comprehensively.A remarkable absorbed power beyond 100 W in flange would be produced by the electromagnetic field from wires.Under natural cooling condition,there is an obvious temperature rise about 40℃in the flange center after 10 min of current excitation.Three types of water cooling solutions acting on flange surface,e.g.line type,circle type and S type solutions,were proposed to reduce the flange temperature under high alternating current and long working time condition.By the S type water cooling mode,the best cooling effect can be achieved that the maximum temperature rise is about 20℃and the average temperature rise is less than 5℃.展开更多
OBJECTIVE: To investigate the diagnostic significance of lingual flange protrusion for liver metastasis of patients with malignant neoplasia.METHODS: The data of 191 patients with malignant neoplasia were analyzed. Al...OBJECTIVE: To investigate the diagnostic significance of lingual flange protrusion for liver metastasis of patients with malignant neoplasia.METHODS: The data of 191 patients with malignant neoplasia were analyzed. All photos of patients' tongue image were recorded and lingual flange protrusion was the positive standard. χ~2 test for paired data and Kappa test were used to determine the diagnostic value of lingual flange protrusion for metastatic liver cancer. Mann-Whitney U test was used to compare the levels of liver serolog-ical markers. The area under receiver operating characteristic curve(ROC) and logistic regression model were used to analyze the predictive values of lingual flange protrusion, alkaline phosphatase(ALP), and lactate dehydrogenase(LDH) levels.RESULTS: Patients with lingual flange protrusion had a higher risk of liver metastasis than those without it(P < 0.001). There was no significant difference in diagnosis of liver metastasis between lingual flange protrusion and traditional diagnostic criteria(P = 0.541). Kappa was 0.738(P < 0.001). Lingual flange protrusion was significantly correlated with increased serum ALP and LDH levels(P < 0.01).Comparison of ROC curves showed that the diagnostic value of lingual flange protrusion is better than ALP, LDH and the combination of ALP and LDH(P < 0.01). Furthermore, the combined diagnostic values of lingual flange protrusion and ALP,lingual flange protrusion and LDH, and lingual flange protrusion, ALP and LDH are not better than lingual flange protrusion alone(P > 0.05).CONCLUSION: Lingual flange protrusion is a potential diagnostic marker for liver metastasis of patients with malignant neoplasia.展开更多
Jacking force is one of the important safety indicators during pipe jacking construction.Existing models for calculating jacking force are widely used in the calculation of jacking force for pipe with regular cross-se...Jacking force is one of the important safety indicators during pipe jacking construction.Existing models for calculating jacking force are widely used in the calculation of jacking force for pipe with regular cross-sections.In this paper,considering pipe-soil interaction,the cross-sectional characteristics and the distribution characteristics between pipe and soil,the calculation equations for the jacking force of circular steel pipe with flange plate were proposed based on the pressure arch theory.The proposed equations were applied to calculate the jacking force for the Olympic Sports Center Subway Station of Line 9 in Shenyang,China,and the results were compared with the field monitoring data to predict the accurate jacking force.Based on the proposed equations,the influences of the flange plate position and steel pipe diameter on earth pressure around the pipe were analyzed.The functional relationship between the earth pressure and the position of flange plate or the pipe diameter was obtained,which provides design basis and theoretical guidance for engineering practice.展开更多
基金National Natural Science Foundation of China Under Grant No. 51078075a grant from Southeast University (No. 3205000502)the financial support from the State Key Lab of Subtropical Building Science, South China University of Technology under Grant No. 2010KB05
文摘A new type of steel moment resisting frame with bottom flange friction devices (BFFDs) has been developed to provide self-centering capacity and energy dissipation, and to reduce permanent deformations under earthquakes. This paper presents a numerical simulation of self-centering beam-column connections with BFFDs, in which the gap opening/closing at the beam-column interfaces is simulated by using pairs of zero-length elements with compression-only material properties, and the energy dissipation due to friction is simulated by using truss elements with specified hysteretic behavior. In particular, the effect of the friction bolt bearing against the slotted plate in the BFFDs was modeled, so that the increase in lateral force and the loss of friction force due to the bolt bearing could be taken into account. Parallel elastic-perfectly plastic gap (ElasticPPGap) materials in the Open System for Earthquake Engineering Simulation (OpenSees) were used with predefined gaps to specify the sequence that each bolt went into the bearing and the corresponding increase in bending stiffness. The MinMax material in OpenSees is used to specify the minimum and maximum values of strains of the ElasticPPGap materials. To consider the loss of friction force due to bok bearing, a number of parallel hysteretic materials were used, and the failure of these materials in sequence simulated the gradual loss of friction force. Analysis results obtained by using the proposed numerical model are discussed and compared with the test results under cyclic loadings and the seismic loading, respectively.
基金Supported by National Natural Science Foundation of China(Grant No.51305333)Shaanxi Provincial Key Science and Technology Industrial Research Plan of China(Grant No.2014K07-23)Shaanxi Provincial Cooperation Project of China(Grant No.2014SJ-15)
文摘Double?roller clamping spinning(DRCS) is a new process for forming a thin?walled cylinder with a complex surface flange. The process requires a small spinning force,and can visibly improve forming quality and production e ciency. However,the deformation mechanism of the process has not been completely understood. Therefore,both a finite element numerical simulation and experimental research on the DRCS process are carried out. The results show that both radial force and axial force dominate the forming process of DRCS. The deformation area elongates along the radial direction and bends along the axial direction under the action of the two forces. Both the outer edge and round corner of the flange show the tangential tensile stress and radial compressive stress. The middle region shows tensile tangential stress and radial stress,while the inner edge shows compressive tangential stress and radial stress. Tan?gential tensile strain causes a wall thickness reduction in the outer edge and middle regions of the flange. The large compressive thickness strain causes material accumulation and thus,an increase in the wall thickness of the round corner. Because of bending deformation,the round corner shows a large radial tensile strain in addition. The inner edge of the flange shows small radial compressive strain and tensile strain in thickness. Thus,the wall thickness on the inner edge of the flange continues to increase,although the increment is small. Furthermore,microstructure analysis and tensile test results show that the flanged thin?walled cylinder formed by DRCS has good mechanical properties. The results provide instructions for the application of the DRCS process.
基金The project supported by the National Natural Science Foundation of China (19832020)Provincial Natural Science Foundation of Jilin, China (200000519)
文摘Flange earrings of strong anisotropic sheet metals in deep-drawing process are numerically analyzed by the elastic-plastic large deformation finite element formulation based on a discrete Kirchhoff triangle plate shell element model. A Barlat-Lian anisotropic yield function and a quasi-flow corner theory are used in the present formulation. The numerical results are compared with the experimental ones of cylindrical cup drawing process. The focus of the present researches is on the numerical analysis and the constraining scheme of the flange earring of circular sheets with strong anisotropy in square cup drawing process.
基金supported by the Chinese TMSR Strategic Pioneer Science and Technology Project(No.XDA02010000)the Frontier Science Key Program of Chinese Academy of Sciences(No.QYZDY-SSW-JSC016)
文摘Carbonic composite materials and ceramics appear to be excellent structural materials for parts subjected to very high temperatures in molten salt reactors(MSRs), in which the reactor core outlet temperature is normally above 700℃. Because of the high temperature,there are major challenges in the sealing of flanged connections for tubes made of alloys and nonmetallic materials. In this study, an improved method for sealing bolted flange connections for tubes made of dissimilar materials at high temperature is analyzed. The study focuses on the compensation mechanism for the difference in thermal expansion between the bolts and the flanges. An angle is introduced for the sealing surface in the flanged connection to provide effective sealing. The arctangent of the angle is the ratio of the thickness between the theoretical core of the sealing surface and the outside end face of the flange to the distances between the axis of the flanged joint and the theoretical core of the sealing surface of the flange; the sealing surface of the flange, which is made of the same material as the fastening assemblies, faces the fastening assemblies. To ensure effective sealing, the frictional coefficient between the two sealing surfaces should not exceed the tangent of the angle. This result does not agree well with the solution given by previous researchers. Further, in the modified flanged connection, the compression of each bolt in the clamped condition is increased to maintain the compaction force unchanged without increasing the number of bolts on the flanged joint.
文摘The wind turbine with a flanged-diffuser shroud—so called “wind-lens turbine”—is developed as one of high performance wind turbines by Ohya et al. In this paper, the wind turbine performance is investigated for both steady and unsteady winds. The compact-type wind lens turbine shows higher efficiency than the only rotor wind turbine. Also, the flow structure around the compact-type wind turbine is made clear by CFD and PIV in steady wind. Furthermore, the performances of the only rotor and the compact-type wind-lens turbines for unsteady wind are experimentally and numerically investigated. Experimental and numerical results are presented to demonstrate the dependence of frequency of the harmonic oscillating velocity wind on power coefficient. Consequently, the compact-type wind-lens turbine show better performance than the only rotor one in sinusoidally oscillating velocity wind. Furthermore, the numerical estimation can predict the power coefficient in the oscillating flows to an accuracy of 94% to 102%. In addition, the dependence of the turbine performance on turbulent intensity and vortex scale of natural fluctuating wind is presented.
基金supported by a grant from the Science and Technology Bureau of Jilin Province,China (No.20050531)
文摘A new method for the determination of effective flange width under uniform load on simply supported box girder bridges considering shear lag effect is proposed in this paper. Based on the Symplectic Elasticity method, the flange slab of the box girder is simplified into a plane stress plate. Using equilibrium conditions of the plates, the Hamilton dual equations for top plate element is established. The analytical formulas of each plate element considering shear lag effect are derived. The closed polynomial effective width expression of flange slab under uniform load on the whole span length has been obtained. Through examples using the finite element method, the results obtained by the proposed method are examined and the accuracy of the proposed method is verified.
文摘This study was conducted to investigate the maxillary denture bases and occlusal discrepancies using the Vertex Thermosens in comparison with the conventional polymethyl-methacrylate materials. Twenty maxillary denture bases were prepared from the Vertex ThermoSens and a conventional heat-cured denture base materials. Acrylic maxillary second molars were arranged in their respective positions on the ridge. After curing of both types of denture bases, they were deflasked with their respective master casts. Reference points were prepared for measurements of the antero-posterior and cross-arch dimensions at the denture borders using caliper device. Furthermore, the teeth discrepancies were measured between reference points in the ligual aspect of the second maxillary molars. The recorded data was analyzed using SPSS statistical software version 20. The results showed initial shrinkage of both denture bases in the antero-posterior and cross-arch dimensions immediately after decasting. This contraction was compensated gradually during storage in water up to 2 weeks. Regarding the variable time, there was a significant difference between the tested materials. Moreover, the results revealed occlusal discrepancies and shifting of teeth inward immediately after decasting, followed by outward movement after storage in water for 2 weeks. Regarding the variables time and materials, there were significant differences. Both materials exhibited inward shrinkage in the antero-posterior and cross-arch dimensions immediately after decasting. Both denture bases showed inward shifting of teeth immediately after decasting, followed by outward movement after storage in water up to 2 weeks.
基金NSFC(No.19832020)National Automobile Dynamic Simulation Laboratory of China
文摘The Hill's quadric anisotropy yield function and the Barlat-Lian anisotropy yield func- tion describing well anisotropy sheet metal with stronger texture are introduced into a quadric-flow cor- ner constitutive theory of elastic-plastic finite deformation suitable for deformation localization analy- sis.And then,the elastic-plastic large deformation finite element formulation based on the virtual power principle and the discrete Kirchhoff shell element model including the yield functions and the constitutive theory are established.The focus of the present research is on the numerical simulation of the flange earing of the deep-drawing of anisotropy circular sheets,based on the investigated results, the.schemes for controlling the flange earing are proposed.
文摘The hollow flange beam(HFB) is a unique cold-formed steel section developed in Australia for use as a flexural member.It′s a particular cross section with two torsion rigid closed triangular flanges and a comparatively flexible web,and it is a type of high efficient cross section.This paper presents two kinds of new cold-formed flange-closed welding sections named HF1 and HF2 according to different section component and parameters of HFB.Nonlinear finite element method has been adopted to investigate the mechanical properties such as buckling mode,deformation process,rigidity,ductility and correlation curve of two kinds of new section members which being subjected to axial compression,flexure,combined compression and bending.Systematical comparisons of the consumed steel quantities of per unit load carrying capacity between new section members and the same section dimensions of cold-formed C-section members have been carried out.Some conclusions can be drawn from above work that the new sections have some superior properties including higher load carrying capacity and section modulus,sufficient section stiffness,and difficult occurrence for the sub element local buckling.The new sections are suitable for bearing flexure,compression,combined compression and bending.The new sections′ consumed steel quantities of per unit load carrying capacity are almost half as those of the same dimension C-section members′.The experimental investigation is carried out further on the new cold-formed flange-closed welding section members and can be used in the practical engineering.
基金This bark wu suPPorted w suPPorted by the Nabnonal Key Laboratory of Precision HOt Processing of Metals Foundation of China
文摘FEM is used to analyze the influence of interface friction on the material flow and the cause of forming defect in the cold upsetting of tube flange. Based on the FEM simulation results, the relationships between flange width and the extreme friction factors are established. The concept of forming limit diagram for cold upsetting of tube flange is presented.
文摘This study covers optimization of I-sectional flange beams. Scope of this study is limited to medium weight flange beams of Table 1 of IS 808:1983 but it can be further extended for the other sections of this code. Best possible geometric shape of the cross-section is found for maximum performance of the beam with minimum material consumption. All possible loading conditions are considered in the study for which a beam in flexure undergoes in its life. ANSYS software program is used for the analysis and optimizing the sections. It is found that sections MB 125, MB 300 and MB 400 of Table 1 of IS 808 are not the optimum sections but other alternative of these cross-sections is available which within the same material consumption performs better than these sections of IS code.
文摘Compared with general circular flanges, flanges on conical shells have different configurations. In the Chinese national code GBISO, however, there are no related contents about flange design of this kind of type. So, it needs to study loads of flanges of this kind of type. This paper takes the flange connection of a wide angle diffuser in a transonic and supersonic wind tunnel as the background, according to the principles of flange design in Chinese national code GB150, combining the characteristics of flanges of a wide angle diffuser, the loads of flanges have been analyzed, and the equations of loads and their locations have been presented.
基金support from the National Natural Science Foundation of China(Nos.11772158,11502113)the Fundamental Research Funds for Central Universities,China(No.30917011103)。
文摘In this paper,a failure evaluation criterion was proposed for the bolted casing-flange structure under impact loading.Subsequently,ballistic tests with eighteen bolted casing-flange structure specimens were conducted to validate the failure evaluation criterion.Parameter studies were then carried out using the validated FE models.Both the experimental and numerical results demonstrated the accuracy of the failure evaluation criterion.The failure evaluation criterion provided a quick and easy way to determine the failure mode of the casing connection area by using the materials and dimensions of the structure.Based on the failure evaluation criterion,designing the structural failure mode of the bolted casing-flange structure to be between flange failure and bolt failure can improve the impact resistance of the connection area of the aero-engine casings.This investigation revealed that the impact failure is not the unique criterion in evaluating the containment of the casing connection area,structural failure should also be involved in the evaluation criteria.
基金the Special Research Fund for the Natural Science Foundation of Inner Mongolia Autonomous Region(No.2019MS05070)。
文摘Flange joint part is the weak link of wind turbine tower.In view of the special structure,complex stress and easy failure of the connecting bolt of the wind turbine tower flange,the relationship between the external load of the tower section and the internal stress of the bolt is established by the finite element method,and the time series internal stress of the bolt is calculated by the Schmidt-Neuper algorithm.The S-N curve which is suitable for the connecting bolt material of the tower flange is selected by the GL2010 specification.On the basis of Miner’s fatigue cumulative damage theory and rain flow counting method,the fatigue strength of the whole ring bolt is roughly calculated,and the most dangerous part is determined.The axial symmetry model of screw connection is used for accurately calculating the fatigue cumulative damage of the bolt at the dangerous part.The results show that the fatigue life of the bolts in the most dangerous position can meet the requirements,the engineering algorithm has advantages in determining the dangerous part of the whole ring bolt,and the finite element method has high accuracy in predicting the fatigue life of the bolts in the dangerous part.The proposed method is feasible and effective in predicting the fatigue life of the flange joint bolts of the tower.
基金supported by the National Natural Science Foundation of China(Grant Nos.51734008,51522102,51327901 and 51474175)the National Key R&D Program of China(Grant No.2018YFB2001800)the Shannxi Key Industry Chain Program(Grant No.2019ZDLGY05-10)。
文摘The heat transfer characteristics of feedthrough flange under high alternating current excitation were investigated by threedimensional finite element model.The correlations between the heat transfer behaviors and system parameters including applied current,ceramic thickness and working time were discussed comprehensively.A remarkable absorbed power beyond 100 W in flange would be produced by the electromagnetic field from wires.Under natural cooling condition,there is an obvious temperature rise about 40℃in the flange center after 10 min of current excitation.Three types of water cooling solutions acting on flange surface,e.g.line type,circle type and S type solutions,were proposed to reduce the flange temperature under high alternating current and long working time condition.By the S type water cooling mode,the best cooling effect can be achieved that the maximum temperature rise is about 20℃and the average temperature rise is less than 5℃.
基金Supported by National Natural Science Foundation of China(Biomechanics Mechanism of the Anti-Tumor Effects of Softing and Resolving Hard Mass Drugs,No.81473441)
文摘OBJECTIVE: To investigate the diagnostic significance of lingual flange protrusion for liver metastasis of patients with malignant neoplasia.METHODS: The data of 191 patients with malignant neoplasia were analyzed. All photos of patients' tongue image were recorded and lingual flange protrusion was the positive standard. χ~2 test for paired data and Kappa test were used to determine the diagnostic value of lingual flange protrusion for metastatic liver cancer. Mann-Whitney U test was used to compare the levels of liver serolog-ical markers. The area under receiver operating characteristic curve(ROC) and logistic regression model were used to analyze the predictive values of lingual flange protrusion, alkaline phosphatase(ALP), and lactate dehydrogenase(LDH) levels.RESULTS: Patients with lingual flange protrusion had a higher risk of liver metastasis than those without it(P < 0.001). There was no significant difference in diagnosis of liver metastasis between lingual flange protrusion and traditional diagnostic criteria(P = 0.541). Kappa was 0.738(P < 0.001). Lingual flange protrusion was significantly correlated with increased serum ALP and LDH levels(P < 0.01).Comparison of ROC curves showed that the diagnostic value of lingual flange protrusion is better than ALP, LDH and the combination of ALP and LDH(P < 0.01). Furthermore, the combined diagnostic values of lingual flange protrusion and ALP,lingual flange protrusion and LDH, and lingual flange protrusion, ALP and LDH are not better than lingual flange protrusion alone(P > 0.05).CONCLUSION: Lingual flange protrusion is a potential diagnostic marker for liver metastasis of patients with malignant neoplasia.
基金supported by the National Natural Science Foundation of China(No.51878127).
文摘Jacking force is one of the important safety indicators during pipe jacking construction.Existing models for calculating jacking force are widely used in the calculation of jacking force for pipe with regular cross-sections.In this paper,considering pipe-soil interaction,the cross-sectional characteristics and the distribution characteristics between pipe and soil,the calculation equations for the jacking force of circular steel pipe with flange plate were proposed based on the pressure arch theory.The proposed equations were applied to calculate the jacking force for the Olympic Sports Center Subway Station of Line 9 in Shenyang,China,and the results were compared with the field monitoring data to predict the accurate jacking force.Based on the proposed equations,the influences of the flange plate position and steel pipe diameter on earth pressure around the pipe were analyzed.The functional relationship between the earth pressure and the position of flange plate or the pipe diameter was obtained,which provides design basis and theoretical guidance for engineering practice.