This paper presents an analytical scheme for predicting the collapse strength of a flexible pipe, which considers the structural interaction between relevant layers. The analytical results were compared with a FEA mod...This paper presents an analytical scheme for predicting the collapse strength of a flexible pipe, which considers the structural interaction between relevant layers. The analytical results were compared with a FEA model and a number of test data, and showed reasonably good agreement. The theoretical analysis showed that the pressure armor layer enhanced the strength of the carcass against buckling, though the barrier weakened this effect. The collapse strength of pipe was influenced by many factors such as the inner radius of the pipe, the thickness of the layers and the mechanical properties of the materials. For example, an increase in the thickness of the barrier will increase contact pressure and in turn reduce the critical pressure.展开更多
Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve ...Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve the life of the dies in cold rotary forging.The purpose of this work is to reveal the contact force responses in cold rotary forging through the modelling and simulation.For this purpose,a 3D elastic-plastic dynamic explicit FE model of cold rotary forging is developed using the FE code ABAQUS/Explicit.Through the modelling and simulation,the distribution and evolution of the contact force in cold rotary forging is investigated in detail.The experiment has been conducted and the validity of the 3D FE model of cold rotary forging has been verified.The results show that: 1) The contact force distribution is complex and exhibits an obvious non-uniform characteristic in the radial and circumferential directions; 2) The maximum contact force between the upper die and the workpiece is much larger than that between the lower die and the workpiece; 3) The contact force evolution history is periodic and every period experiences three different stages; 4) The total normal contact force is much larger than the total shear contact force at any given time.展开更多
A FEM model for a failed industrial example of roll forging was established to analyze the generation mechanisms of the mismatch of size and shape of two spring board.To demonstrate the formulation of these defects,th...A FEM model for a failed industrial example of roll forging was established to analyze the generation mechanisms of the mismatch of size and shape of two spring board.To demonstrate the formulation of these defects,the bites condition and contact status between rectangular groove and workpiece during rolling the first and second spring boards were analyzed.Then,a new oval-diamond groove combining oval groove and diamond groove was presented to eliminate these defects.By analyzing field variables under the same deformation degree,the larger friction can be obtained on the contact surface of workpiece and the oval-diamond groove.The physical experiment validates that the oval-diamond groove can eliminate these defects effectively,and the size of part is in good agreement with design requirement.展开更多
Finite element method(FEM) was used to investigate the effect of the number of layers on the bond strength for the brittle coating/substrate materials at contact load condition,which has not been addressed previously....Finite element method(FEM) was used to investigate the effect of the number of layers on the bond strength for the brittle coating/substrate materials at contact load condition,which has not been addressed previously.The maximum shear stress was used to act as the criterion of the bonded strength.This paper discussed the relationship between the number of coating layers and the maximum shear stress of the layer/substrate interface.Firstly,the results of the FEM and the Hertz analytical method were compared to verify the accuracy of the FEM model.It was found that with the increase in the number of coating layers,the position of the suddenly changed stress along the z axis is transformed from the interface to the external surface of the coating.Finally,the increase in the number of layers contributes to the decrement of the stress along the x axis.展开更多
文摘This paper presents an analytical scheme for predicting the collapse strength of a flexible pipe, which considers the structural interaction between relevant layers. The analytical results were compared with a FEA model and a number of test data, and showed reasonably good agreement. The theoretical analysis showed that the pressure armor layer enhanced the strength of the carcass against buckling, though the barrier weakened this effect. The collapse strength of pipe was influenced by many factors such as the inner radius of the pipe, the thickness of the layers and the mechanical properties of the materials. For example, an increase in the thickness of the barrier will increase contact pressure and in turn reduce the critical pressure.
基金Project(51105287)supported by the National Natural Science Foundation of ChinaProject(2012BAA08003)supported by the Key Research and Development Project of New Products and New Technologies of Hubei Province,ChinaProject(2013M531750)supported by China Postdoctoral Science Foundation
文摘Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve the life of the dies in cold rotary forging.The purpose of this work is to reveal the contact force responses in cold rotary forging through the modelling and simulation.For this purpose,a 3D elastic-plastic dynamic explicit FE model of cold rotary forging is developed using the FE code ABAQUS/Explicit.Through the modelling and simulation,the distribution and evolution of the contact force in cold rotary forging is investigated in detail.The experiment has been conducted and the validity of the 3D FE model of cold rotary forging has been verified.The results show that: 1) The contact force distribution is complex and exhibits an obvious non-uniform characteristic in the radial and circumferential directions; 2) The maximum contact force between the upper die and the workpiece is much larger than that between the lower die and the workpiece; 3) The contact force evolution history is periodic and every period experiences three different stages; 4) The total normal contact force is much larger than the total shear contact force at any given time.
基金Project(51275543)supported by the National Natural Science Foundation of ChinaProject(cstc2009aa3012-1)supported by the Key Program of Chongqing Science and Technology Foundation,China
文摘A FEM model for a failed industrial example of roll forging was established to analyze the generation mechanisms of the mismatch of size and shape of two spring board.To demonstrate the formulation of these defects,the bites condition and contact status between rectangular groove and workpiece during rolling the first and second spring boards were analyzed.Then,a new oval-diamond groove combining oval groove and diamond groove was presented to eliminate these defects.By analyzing field variables under the same deformation degree,the larger friction can be obtained on the contact surface of workpiece and the oval-diamond groove.The physical experiment validates that the oval-diamond groove can eliminate these defects effectively,and the size of part is in good agreement with design requirement.
基金supported by the National Natural Science Foundation of China (Grant No. 51005102)Postdoctoral Science Foundation of Jiangsu Province (Grant No. 1002028C)+1 种基金Postdoctoral Science Foundation of China (Grant No. 20110491366)the State Key Laboratory of Tribology of Tsinghua University (Grant No. SKLTKF10B04)
文摘Finite element method(FEM) was used to investigate the effect of the number of layers on the bond strength for the brittle coating/substrate materials at contact load condition,which has not been addressed previously.The maximum shear stress was used to act as the criterion of the bonded strength.This paper discussed the relationship between the number of coating layers and the maximum shear stress of the layer/substrate interface.Firstly,the results of the FEM and the Hertz analytical method were compared to verify the accuracy of the FEM model.It was found that with the increase in the number of coating layers,the position of the suddenly changed stress along the z axis is transformed from the interface to the external surface of the coating.Finally,the increase in the number of layers contributes to the decrement of the stress along the x axis.
