This study aims to develop a framework based on the Nadal formula to assess train derailment risk. Monte Carlo simulation was adopted to develop 10000 sets of random parameters to assess train derailment risk subject ...This study aims to develop a framework based on the Nadal formula to assess train derailment risk. Monte Carlo simulation was adopted to develop 10000 sets of random parameters to assess train derailment risk subject to the curvature radius of the track, the difference between the flange angle and the equivalent conicity, and accelerations from 250 to 989.22 gal during horizontal earthquake. The results indicated that railway in Taiwan, China has no derailment risk under normal conditions. However, when earthquakes occur, the derailment risk increases with the unloading factor which is caused by seismic force. The results also show that equivalent conicity increases derailment risk;as a result, equivalent conicity should be listed as one of maintenance priorities. In addition, among all train derailment factors, flange angle, equivalent conicity and unload factors are the most significant ones.展开更多
It is necessary to use the integrated stainless steel pipe having two fitting bodies without welds while train travelling at high speed. In order to form this type of integrated stainless steel pipe, the method of pre...It is necessary to use the integrated stainless steel pipe having two fitting bodies without welds while train travelling at high speed. In order to form this type of integrated stainless steel pipe, the method of preforming combined finish forming process is developed. The preforming process is characterized by flaring combined upsetting for left fitting body which is like a flange, and is characterized by tube axial compressive process under die constraint for right fitting body which is like a double-wall pipe. The finite element simulations of the processes are carried out by software package DEFORM, and the results indicate that: 1) left or right fitting body can be formed by a two-step forming process without folding and under-filling defects; 2) by using two-step forming, strain and stress in left fitting body are larger than those in right fitting body, and deformation in right fitting body is more homogenous than the deformation in left fitting body; 3) two or more preforming steps may be needed for left fitting body considering the distributions of strain and stress.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
文摘This study aims to develop a framework based on the Nadal formula to assess train derailment risk. Monte Carlo simulation was adopted to develop 10000 sets of random parameters to assess train derailment risk subject to the curvature radius of the track, the difference between the flange angle and the equivalent conicity, and accelerations from 250 to 989.22 gal during horizontal earthquake. The results indicated that railway in Taiwan, China has no derailment risk under normal conditions. However, when earthquakes occur, the derailment risk increases with the unloading factor which is caused by seismic force. The results also show that equivalent conicity increases derailment risk;as a result, equivalent conicity should be listed as one of maintenance priorities. In addition, among all train derailment factors, flange angle, equivalent conicity and unload factors are the most significant ones.
基金Project(51305334)supported by the National Natural Science Foundation of ChinaProject(51335009)supported by the National Natural Science Foundation of China for Key Program+1 种基金Project(CXY1442(4))supported by the Science and Technology Planning Project of Xi’an,ChinaProject supported by Shaanxi Province Postdoctoral Science Research Program of China
文摘It is necessary to use the integrated stainless steel pipe having two fitting bodies without welds while train travelling at high speed. In order to form this type of integrated stainless steel pipe, the method of preforming combined finish forming process is developed. The preforming process is characterized by flaring combined upsetting for left fitting body which is like a flange, and is characterized by tube axial compressive process under die constraint for right fitting body which is like a double-wall pipe. The finite element simulations of the processes are carried out by software package DEFORM, and the results indicate that: 1) left or right fitting body can be formed by a two-step forming process without folding and under-filling defects; 2) by using two-step forming, strain and stress in left fitting body are larger than those in right fitting body, and deformation in right fitting body is more homogenous than the deformation in left fitting body; 3) two or more preforming steps may be needed for left fitting body considering the distributions of strain and stress.
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.
