The steel reinforced plastic pipe is a kind of green environmental protection pipelines with double-sides corrosionresisting and better withstanding to medium working pressure.The structure and technical process of th...The steel reinforced plastic pipe is a kind of green environmental protection pipelines with double-sides corrosionresisting and better withstanding to medium working pressure.The structure and technical process of this pipe are described briefly in this paper,and the finite element analysis has been done for the sake of understanding the distributions of stress and displacement inside this pipe under hydrostatic pressure.The analysis results are very important for safety application of the steel reinforced plastic pipe.展开更多
The steel reinforced plastic pipe is a new kind of pressure pipe. It is made up with steelwires and plastic. Because reinforced skeleton of the steel wire increase the complexityof plastic flow during the extrusion ph...The steel reinforced plastic pipe is a new kind of pressure pipe. It is made up with steelwires and plastic. Because reinforced skeleton of the steel wire increase the complexityof plastic flow during the extrusion phase, the traditional design criteria of extrusiondie is not suitable. The study on extrusion die of the kind of pipe is very importantstep in produce development. Using finite element (FE) method in this paper, theflow rule of molten plastic inside the die has been predicted and a groap of optimalstructural parameters was obtained. These results are helpful for reducing the designcycle and improve the quality of the final product.展开更多
The modulus of soil reaction,representing the stiffness of a soil surrounding pipes,is a critical parameter in the design of buried flexible pipes.This study conducted plate loading tests on corrugated polyvinyl chlor...The modulus of soil reaction,representing the stiffness of a soil surrounding pipes,is a critical parameter in the design of buried flexible pipes.This study conducted plate loading tests on corrugated polyvinyl chloride,smooth polyvinyl chloride,and high-density polyethylene pipes buried in lightweight cellular concrete(LCC)backfills at densities of 400,475,550,and 650 kg/m^(3)to investigate the pipe deformation behavior and moduli of soil reaction.In addition,this study examined the effects of the narrow trench condition on the pipe deformation and modulus of soil reaction.In these tests,the vertical and horizontal diameter changes of pipes under the vertical pressures applied through a hydraulic jack were measured.Test results reveal that the average moduli of soil reaction of plastic pipes within a wide trench backfilled by the LCCs at densities of 400,475,550,and 650 kg/m^(3)were back-calculated as 66,99,133,and 205 MPa,respectively,using the modified Iowa formula.Furthermore,the back-calculated moduli of soil reaction for LCCs exhibited linear relationships with their densities and unconfined compressive strengths and were higher than the recommended values for the commonly used soil backfills.Based on the vertical deformation criterion of 5%pipe diameter,the ultimate bearing capacities of flexible pipes buried in wide LCCs at densities of 475,550,and 650 kg/m^(3)exceeded 500 kPa.The LCC with a narrow trench exhibited a lower modulus of soil reaction and ultimate bearing capacity but a larger pipe diameter change.展开更多
With von Mises yield criterion,the loading range of Net Section Collapse(NSC) Criteria is extended from combined tension and bending loadings to combined bending,torsion and internal pressure loadings.A new theoretica...With von Mises yield criterion,the loading range of Net Section Collapse(NSC) Criteria is extended from combined tension and bending loadings to combined bending,torsion and internal pressure loadings.A new theoretical analyzing method of plastic limit load for pressure pipe with incomplete welding defects based on the extended NSC Criteria is presented and the correlative formulas are deduced,the influences of pipe curvature,circumferential length and depth of incomplete welding defects on the plastic limit load of pressure pipe are considered as well in this method.Meanwhile,according to the orthogonal experimental design method,the plastic limit loads are calculated by the finite element method and compared with the theoretical values.The results show that the expressions of plastic limit load of pressure pipe with incomplete welding defects under bending,torsion and internal pressure based on extended NSC criteria are reliable.The study provides an important theoretical basis for the establishment of safety assessment measure towards pressure pipe with incomplete welding defects.展开更多
In the framework of finite deformation theory, the burst failure analysis of end-opened defect-free pipes with plastic anisotropy under internal pressure is carried out. The analytical solutions of burst pressure and ...In the framework of finite deformation theory, the burst failure analysis of end-opened defect-free pipes with plastic anisotropy under internal pressure is carried out. The analytical solutions of burst pressure and the corresponding equivalent stress and strain are obtained for thin-walled pipes, which can take into account the effects of material plastic anisotropy and strain hardening exponent. The influences of plastic anisotropy on the burst pressure and the corresponding equivalent stress and strain are discussed. It is shown that the burst pressure and the corresponding equivalent stress and strain are dependent upon the plastic anisotropy of material, and the degree of dependence is related to the strain hardening exponent of material. In addition, the effects of the strain hardening exponent on burst failure are investigated.展开更多
In the present investigation, a pipe inner-surface grinding（PISG） technique was developed to fabricate nanostructure in the inner-surface of an austenitic 304 stainless steel pipe. PISG was performed by high speed s...In the present investigation, a pipe inner-surface grinding（PISG） technique was developed to fabricate nanostructure in the inner-surface of an austenitic 304 stainless steel pipe. PISG was performed by high speed shearing with hard sphere tips, leading to gradient distribution of strain, strain rate and strain gradient along depth. Nano-austenite with an average boundary spacing of 20 nm was generated, followed by deformation microstructure characterized by shear bands, multi-and uni-directional twins and planar dislocation arrays. Deformation induced grain refinement of austenitic 304 stainless steel with low stacking fault energy（SFE） covering 4–5 order＇s magnitude of length scales toward nanometer regime was unified.展开更多
Objective To assess the health safety of copper, steel and plastic water pipes by field water quality investigations. Methods Four consumers were randomly selected for each type of water pipes. Two consumers of every ...Objective To assess the health safety of copper, steel and plastic water pipes by field water quality investigations. Methods Four consumers were randomly selected for each type of water pipes. Two consumers of every type of the water pipes had used the water pipes for more than 1 year and the other 2 consumers had used the water pipes for less than 3 months. The terminal volume of tap water in copper and steel water pipes should be not less than 0.1 liter, whereas that in plastic water pipes should be not less than 1 liter. Results The mean values of the experimental results in the second field water quality investigation of the copper and steel water pipes met the Sanitary Standards for Drinking Water Quality. The items of water sample of the plastic water pipes met the requirements of the Sanitary Standards for Drinking Water Quality. Conclusion Copper, steel, and plastic pipes can be used as drinking water pipes.展开更多
The fiberglass reinforced plastic （FRP） pipelines have been used widely in oil-gas gathering and transportation. The defects of FRP pipelines would increase with the extension of service time. However, it is very di...The fiberglass reinforced plastic （FRP） pipelines have been used widely in oil-gas gathering and transportation. The defects of FRP pipelines would increase with the extension of service time. However, it is very difficult to detect the defects of FRP pipelines on-spot quickly. In this paper, a new method detecting defects for FRP pipes has been provided based on the NMR. The proton density distributions have been obtained at different depth of FRP components using single-side NMR. The experimental results show that there is a significant change of proton density distribution at the location of defects. And, these results would be useful for defects inspection of composite material component.展开更多
Nowadays, thin-walled super-diameter pipes are produced by the method of plastic bending of sheets. After a sheet is bent into a pipe and its ends are welded, a pipe billet is subjected to expansion deformation. The t...Nowadays, thin-walled super-diameter pipes are produced by the method of plastic bending of sheets. After a sheet is bent into a pipe and its ends are welded, a pipe billet is subjected to expansion deformation. The technology of forming end areas of a sheet is developed and formulaes forming forces equations are deduced. Experimental investigations of deformation are undertaken.展开更多
Stresses and deformation states of pipe bending are investigated under loading or unloading with various pipe materials, size, bending radius and deformation temperature. A theorem of springback of large diameter pipe...Stresses and deformation states of pipe bending are investigated under loading or unloading with various pipe materials, size, bending radius and deformation temperature. A theorem of springback of large diameter pipe bending is presented. The experiments are carried out with pipe materials of 20, 10CrMo910 and 12Cr1MoV steel. Results of computations are in good agreement with experiments.展开更多
文摘The steel reinforced plastic pipe is a kind of green environmental protection pipelines with double-sides corrosionresisting and better withstanding to medium working pressure.The structure and technical process of this pipe are described briefly in this paper,and the finite element analysis has been done for the sake of understanding the distributions of stress and displacement inside this pipe under hydrostatic pressure.The analysis results are very important for safety application of the steel reinforced plastic pipe.
文摘The steel reinforced plastic pipe is a new kind of pressure pipe. It is made up with steelwires and plastic. Because reinforced skeleton of the steel wire increase the complexityof plastic flow during the extrusion phase, the traditional design criteria of extrusiondie is not suitable. The study on extrusion die of the kind of pipe is very importantstep in produce development. Using finite element (FE) method in this paper, theflow rule of molten plastic inside the die has been predicted and a groap of optimalstructural parameters was obtained. These results are helpful for reducing the designcycle and improve the quality of the final product.
基金supported by the CEMATRIX Corp.The authors would like to thank technicians David Woody,Kent Dye,and Meyer Carey in the Civil,Environmental,&Architectural Engineering Department at the University of Kansas,for their great assistance in modifying and calibrating the test devices used in this studyThe authors also would like to appreciate Ph.D.student Alsharari Turki from the University of Kansas and formerly visiting student Hsin-Ming Wu at the University of Kansas,and Albert Fang from CEMATRIX for their great help on the model tests.Josh Beakley at the American Concrete Pipe Association provided valuable comments and suggestions for the data analysis of soil reaction modulus.
文摘The modulus of soil reaction,representing the stiffness of a soil surrounding pipes,is a critical parameter in the design of buried flexible pipes.This study conducted plate loading tests on corrugated polyvinyl chloride,smooth polyvinyl chloride,and high-density polyethylene pipes buried in lightweight cellular concrete(LCC)backfills at densities of 400,475,550,and 650 kg/m^(3)to investigate the pipe deformation behavior and moduli of soil reaction.In addition,this study examined the effects of the narrow trench condition on the pipe deformation and modulus of soil reaction.In these tests,the vertical and horizontal diameter changes of pipes under the vertical pressures applied through a hydraulic jack were measured.Test results reveal that the average moduli of soil reaction of plastic pipes within a wide trench backfilled by the LCCs at densities of 400,475,550,and 650 kg/m^(3)were back-calculated as 66,99,133,and 205 MPa,respectively,using the modified Iowa formula.Furthermore,the back-calculated moduli of soil reaction for LCCs exhibited linear relationships with their densities and unconfined compressive strengths and were higher than the recommended values for the commonly used soil backfills.Based on the vertical deformation criterion of 5%pipe diameter,the ultimate bearing capacities of flexible pipes buried in wide LCCs at densities of 475,550,and 650 kg/m^(3)exceeded 500 kPa.The LCC with a narrow trench exhibited a lower modulus of soil reaction and ultimate bearing capacity but a larger pipe diameter change.
基金Project (No. X106871) supported by the Natural Science Foundation of Zhejiang Province,China
文摘With von Mises yield criterion,the loading range of Net Section Collapse(NSC) Criteria is extended from combined tension and bending loadings to combined bending,torsion and internal pressure loadings.A new theoretical analyzing method of plastic limit load for pressure pipe with incomplete welding defects based on the extended NSC Criteria is presented and the correlative formulas are deduced,the influences of pipe curvature,circumferential length and depth of incomplete welding defects on the plastic limit load of pressure pipe are considered as well in this method.Meanwhile,according to the orthogonal experimental design method,the plastic limit loads are calculated by the finite element method and compared with the theoretical values.The results show that the expressions of plastic limit load of pressure pipe with incomplete welding defects under bending,torsion and internal pressure based on extended NSC criteria are reliable.The study provides an important theoretical basis for the establishment of safety assessment measure towards pressure pipe with incomplete welding defects.
文摘In the framework of finite deformation theory, the burst failure analysis of end-opened defect-free pipes with plastic anisotropy under internal pressure is carried out. The analytical solutions of burst pressure and the corresponding equivalent stress and strain are obtained for thin-walled pipes, which can take into account the effects of material plastic anisotropy and strain hardening exponent. The influences of plastic anisotropy on the burst pressure and the corresponding equivalent stress and strain are discussed. It is shown that the burst pressure and the corresponding equivalent stress and strain are dependent upon the plastic anisotropy of material, and the degree of dependence is related to the strain hardening exponent of material. In addition, the effects of the strain hardening exponent on burst failure are investigated.
基金supported financially by the Hundred Outstanding Creative Talents Projects in University of Hebei ProvinceChina, the Project Program of Heavy Machinery Collaborative Innovation Center+1 种基金the Natural Science Foundation of Hebei Province, China (No. E2018203312)the Postdoctoral Science Foundation of Hebei Province, China
文摘In the present investigation, a pipe inner-surface grinding（PISG） technique was developed to fabricate nanostructure in the inner-surface of an austenitic 304 stainless steel pipe. PISG was performed by high speed shearing with hard sphere tips, leading to gradient distribution of strain, strain rate and strain gradient along depth. Nano-austenite with an average boundary spacing of 20 nm was generated, followed by deformation microstructure characterized by shear bands, multi-and uni-directional twins and planar dislocation arrays. Deformation induced grain refinement of austenitic 304 stainless steel with low stacking fault energy（SFE） covering 4–5 order＇s magnitude of length scales toward nanometer regime was unified.
基金This work was sponsored by the International Copper Association.
文摘Objective To assess the health safety of copper, steel and plastic water pipes by field water quality investigations. Methods Four consumers were randomly selected for each type of water pipes. Two consumers of every type of the water pipes had used the water pipes for more than 1 year and the other 2 consumers had used the water pipes for less than 3 months. The terminal volume of tap water in copper and steel water pipes should be not less than 0.1 liter, whereas that in plastic water pipes should be not less than 1 liter. Results The mean values of the experimental results in the second field water quality investigation of the copper and steel water pipes met the Sanitary Standards for Drinking Water Quality. The items of water sample of the plastic water pipes met the requirements of the Sanitary Standards for Drinking Water Quality. Conclusion Copper, steel, and plastic pipes can be used as drinking water pipes.
文摘The fiberglass reinforced plastic （FRP） pipelines have been used widely in oil-gas gathering and transportation. The defects of FRP pipelines would increase with the extension of service time. However, it is very difficult to detect the defects of FRP pipelines on-spot quickly. In this paper, a new method detecting defects for FRP pipes has been provided based on the NMR. The proton density distributions have been obtained at different depth of FRP components using single-side NMR. The experimental results show that there is a significant change of proton density distribution at the location of defects. And, these results would be useful for defects inspection of composite material component.
文摘Nowadays, thin-walled super-diameter pipes are produced by the method of plastic bending of sheets. After a sheet is bent into a pipe and its ends are welded, a pipe billet is subjected to expansion deformation. The technology of forming end areas of a sheet is developed and formulaes forming forces equations are deduced. Experimental investigations of deformation are undertaken.
文摘Stresses and deformation states of pipe bending are investigated under loading or unloading with various pipe materials, size, bending radius and deformation temperature. A theorem of springback of large diameter pipe bending is presented. The experiments are carried out with pipe materials of 20, 10CrMo910 and 12Cr1MoV steel. Results of computations are in good agreement with experiments.
