The interfacial behavior of pipe joints is studied in this paper. Firstly, through nonlinear fracture mechanics, the analytical expressions of interfacial shear stress and the load- displacement relationship at loaded...The interfacial behavior of pipe joints is studied in this paper. Firstly, through nonlinear fracture mechanics, the analytical expressions of interfacial shear stress and the load- displacement relationship at loaded end of pipe joints under torsion loads are obtained. Thus the shear stress propagation and the debonding process of the whole interface for different bond lengths can be predicted. Secondly, through the analytical solutions, the influences of different bond lengths on the load-displacement curve and the ultimate load are studied. The stress trans- fer mechanism, the interface crack propagation and the ductility behavior of the joints can be explained.展开更多
Analysis as well as application of ultra-high pressure hydraulic system and elements has become a trend.The structure and operation principle of a new type of ultra-high pressure pipe joint is introduced.The structure...Analysis as well as application of ultra-high pressure hydraulic system and elements has become a trend.The structure and operation principle of a new type of ultra-high pressure pipe joint is introduced.The structure of the new type of ultra-high pressure pipe joint is simple and is easy to be produced.The finite element model on two working conditions(preload condition with 30 N·m torque and static-loading condition with 70 MPa pressure)is built and computed.The width of contact area,the equivalent stress status,as well as the contact pressure status are plotted and analyzed.According to the national standard,test on air-tightness,blasting,and cyclic endurance is conducted and the results show that the new type of ultra-high pressure pipe joint has the sealability for ultra-high pressure up to 70 MPa,and the DN6 ultra-high pressure pipe joint can provide effective seal under70 MPa fluid pressure.The research can provide a thinking and method on designing ultra-high pressure pipe joint and push forward the development of ultra-high pressure hydraulic system.展开更多
The out-of-plane distortion induced in a multi-pass circumferential fillet welding of tube to pipe under different weld sequences and directions was studied using Finite Element Method(FEM) based Sysweld software and ...The out-of-plane distortion induced in a multi-pass circumferential fillet welding of tube to pipe under different weld sequences and directions was studied using Finite Element Method(FEM) based Sysweld software and verified experimentally. The FEM analyses consisted of thermal and mechanical analyses.Thermal analysis was validated with experimental transient temperature measurements. In the mechanical analysis, three different weld sequences and directions were considered to understand the mechanism of out-of-plane distortion in the tube to pipe T-joints. It was learnt that the welding direction plays a major role in minimizing the out-of-plane distortion. Further, during circumferential fillet welding of the tube to pipe component, the out-of-plane distortion generated in the x direction was primarily influenced by heat input due to the start and stop points, whereas the distortion in the z direction was influenced by time lag and welding direction. The FEM predicted distortion was compared with experimental measurements and the mechanism of out-of-plane distortion was confirmed.展开更多
In this study, a number of nonlinear time-history dynamic analyses are conducted on a part of Tehran water distribution network to investigate its functionality during transient large ground motions. The network is of...In this study, a number of nonlinear time-history dynamic analyses are conducted on a part of Tehran water distribution network to investigate its functionality during transient large ground motions. The network is of 950-meter length, consisting of ductile iron pipes segments of 6-meter length. Pipes are modeled using beam elements and springs characterize the connections. Considering the time lag between support inputs, and the nonlinear soil-pipe interaction, by scaling the amplitude of the Tab as earthquake record, incremental dynamic analysis is carried out on the network in two orthogonal directions and the sensitivity of the network response is examined. Furthermore, the effects of variations in soil damping and soil spring stiffness are also studied in the network analysis. Finally the effect of changes in angle between incoming wave and pipeline is considered on a simplified network. Results show that the points other than critical ones at network intersections remain almost intact and when the angle of incidence is 30 degrees the stress and rotation peak.展开更多
The copper-based shape memory alloy pipe joint was applied in the field of oil pipelines jointing as well as installing. It has many advantages than anything. In the paper, the basic principle and connection influence...The copper-based shape memory alloy pipe joint was applied in the field of oil pipelines jointing as well as installing. It has many advantages than anything. In the paper, the basic principle and connection influence factors of copper-based shape memory alloy pipe joint were described. Experimental results shows the copper-based shape memory alloy pipe joints can be used in oilfield oil pipeline connection and it can solve the inner pipe joint corrosion damage problem by welding.展开更多
Crack opening displacement(COD) was applied to characterize the fracture initiation of the tough high density polyethylene. Normal single side notched three point bend specimens and silica rubber replica techniques ...Crack opening displacement(COD) was applied to characterize the fracture initiation of the tough high density polyethylene. Normal single side notched three point bend specimens and silica rubber replica techniques were used to study the characteristic COD of high density polyethylene pipe and its butt fusion joints including the weld fusion zone and heat affected zone at different temperature from -78 ℃ to 20 ℃ . Testing results show that the characteristic COD appears to depend on the structural features that are determined by welding process and the testing temperature. As the temperature is lowered, the characteristic COD of all zones studied decreases. Because the welding process significantly changes some structural feature of the material, characteristic COD of the weld fusion zone is the smallest one among those of the three zones. The results can be used for the engineering design and failure analysis of HDPE pipe.展开更多
基金supported by the Science and Technology Scheme of Guangzhou City(No.201510010013)the Science and Technology Scheme of Guangdong Province(No.2012A030200003)the National Natural Science Foundation of China(No.11032005)
文摘The interfacial behavior of pipe joints is studied in this paper. Firstly, through nonlinear fracture mechanics, the analytical expressions of interfacial shear stress and the load- displacement relationship at loaded end of pipe joints under torsion loads are obtained. Thus the shear stress propagation and the debonding process of the whole interface for different bond lengths can be predicted. Secondly, through the analytical solutions, the influences of different bond lengths on the load-displacement curve and the ultimate load are studied. The stress trans- fer mechanism, the interface crack propagation and the ductility behavior of the joints can be explained.
基金Supported by the 2015 Industrial Transformation and Upgrading of Strong Base Project(TC150B5C0-29)the National Key Basic Research Program of China(2014CB046400)
文摘Analysis as well as application of ultra-high pressure hydraulic system and elements has become a trend.The structure and operation principle of a new type of ultra-high pressure pipe joint is introduced.The structure of the new type of ultra-high pressure pipe joint is simple and is easy to be produced.The finite element model on two working conditions(preload condition with 30 N·m torque and static-loading condition with 70 MPa pressure)is built and computed.The width of contact area,the equivalent stress status,as well as the contact pressure status are plotted and analyzed.According to the national standard,test on air-tightness,blasting,and cyclic endurance is conducted and the results show that the new type of ultra-high pressure pipe joint has the sealability for ultra-high pressure up to 70 MPa,and the DN6 ultra-high pressure pipe joint can provide effective seal under70 MPa fluid pressure.The research can provide a thinking and method on designing ultra-high pressure pipe joint and push forward the development of ultra-high pressure hydraulic system.
文摘The out-of-plane distortion induced in a multi-pass circumferential fillet welding of tube to pipe under different weld sequences and directions was studied using Finite Element Method(FEM) based Sysweld software and verified experimentally. The FEM analyses consisted of thermal and mechanical analyses.Thermal analysis was validated with experimental transient temperature measurements. In the mechanical analysis, three different weld sequences and directions were considered to understand the mechanism of out-of-plane distortion in the tube to pipe T-joints. It was learnt that the welding direction plays a major role in minimizing the out-of-plane distortion. Further, during circumferential fillet welding of the tube to pipe component, the out-of-plane distortion generated in the x direction was primarily influenced by heat input due to the start and stop points, whereas the distortion in the z direction was influenced by time lag and welding direction. The FEM predicted distortion was compared with experimental measurements and the mechanism of out-of-plane distortion was confirmed.
文摘In this study, a number of nonlinear time-history dynamic analyses are conducted on a part of Tehran water distribution network to investigate its functionality during transient large ground motions. The network is of 950-meter length, consisting of ductile iron pipes segments of 6-meter length. Pipes are modeled using beam elements and springs characterize the connections. Considering the time lag between support inputs, and the nonlinear soil-pipe interaction, by scaling the amplitude of the Tab as earthquake record, incremental dynamic analysis is carried out on the network in two orthogonal directions and the sensitivity of the network response is examined. Furthermore, the effects of variations in soil damping and soil spring stiffness are also studied in the network analysis. Finally the effect of changes in angle between incoming wave and pipeline is considered on a simplified network. Results show that the points other than critical ones at network intersections remain almost intact and when the angle of incidence is 30 degrees the stress and rotation peak.
文摘The copper-based shape memory alloy pipe joint was applied in the field of oil pipelines jointing as well as installing. It has many advantages than anything. In the paper, the basic principle and connection influence factors of copper-based shape memory alloy pipe joint were described. Experimental results shows the copper-based shape memory alloy pipe joints can be used in oilfield oil pipeline connection and it can solve the inner pipe joint corrosion damage problem by welding.
文摘Crack opening displacement(COD) was applied to characterize the fracture initiation of the tough high density polyethylene. Normal single side notched three point bend specimens and silica rubber replica techniques were used to study the characteristic COD of high density polyethylene pipe and its butt fusion joints including the weld fusion zone and heat affected zone at different temperature from -78 ℃ to 20 ℃ . Testing results show that the characteristic COD appears to depend on the structural features that are determined by welding process and the testing temperature. As the temperature is lowered, the characteristic COD of all zones studied decreases. Because the welding process significantly changes some structural feature of the material, characteristic COD of the weld fusion zone is the smallest one among those of the three zones. The results can be used for the engineering design and failure analysis of HDPE pipe.
