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
The quasi-static explicit finite element method (FEM) and element free Galerkin (EFG) method are applied to trace the post-buckling equilibrium path of thin-walled members in this paper. The factors that primarily con...The quasi-static explicit finite element method (FEM) and element free Galerkin (EFG) method are applied to trace the post-buckling equilibrium path of thin-walled members in this paper. The factors that primarily control the explicit buckling solutions, such as the computation time, loading function and dynamic relaxation, are investigated and suggested for the buckling analysis of thin-walled members. Three examples of different buckling modes, namely snap-through, overall and local buckling, are studied based on the implicit FEM, quasi-static explicit FEM and EFG method via the commercial software LS-DYNA. The convergence rate and accuracy of the explicit methods are compared with the conventional implicit arc-length method. It is drawn that EFG quasi-static explicit buckling analysis presents the same accurate results as implicit finite element solution, but is without convergence problem and of less-consumption of computing time than FEM.展开更多
为提高防冲支架能量吸收性能以应对煤炭资源深部开采趋势下的冲击地压频发问题,提出了一种具有圆形与多边形混合截面的多胞薄壁吸能构件应用于防冲支架立柱。基于简化超折叠单元(Simplified Super Folding Element,SSFE)理论剖析了不同...为提高防冲支架能量吸收性能以应对煤炭资源深部开采趋势下的冲击地压频发问题,提出了一种具有圆形与多边形混合截面的多胞薄壁吸能构件应用于防冲支架立柱。基于简化超折叠单元(Simplified Super Folding Element,SSFE)理论剖析了不同截面形状和肋板布局的多胞薄壁吸能构件能量耗散途径,构建了轴向压溃条件下吸能构件的能量吸收平衡方程,并推导出了等厚度和非等厚度2种吸能构件平均支反力预测公式;通过轴向压溃仿真获得了各类型多胞薄壁吸能构件吸能量曲线、支反力曲线以及屈曲变形形态,发现圆形与八边形混合截面、边延伸肋板布局的多胞薄壁吸能构件(P8-2类型)具备相对吸能优势,深入考察了内嵌管截面尺寸、薄壁管壁厚和肋板厚度对其吸能效果的影响规律,即:3种结构参数对弯曲褶皱形态和塑性铰数量影响显著,对吸能特性参数有着不同且非简单单向变化的影响趋势,同时验证了基于SSFE理论的平均支反力理论模型具有较高预测精度;依托均匀试验数据,拟合出了吸能特性参数关于构件结构参数的回归方程,并利用NSGA-II遗传算法进行优化求解,最终确定多胞薄壁吸能构件内嵌管截面尺寸为122 mm,薄壁管壁厚度为2.6 mm,肋板厚度为2.7 mm;进一步通过轴向压溃仿真验证与对比分析,结果表明:经结构参数优化后的多胞薄壁吸能构件具备更好的能量吸收效果且支反力波动较小,可使让位防冲过程更加可靠,能够为防冲吸能构件设计提供有益参考。展开更多
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.
文摘The quasi-static explicit finite element method (FEM) and element free Galerkin (EFG) method are applied to trace the post-buckling equilibrium path of thin-walled members in this paper. The factors that primarily control the explicit buckling solutions, such as the computation time, loading function and dynamic relaxation, are investigated and suggested for the buckling analysis of thin-walled members. Three examples of different buckling modes, namely snap-through, overall and local buckling, are studied based on the implicit FEM, quasi-static explicit FEM and EFG method via the commercial software LS-DYNA. The convergence rate and accuracy of the explicit methods are compared with the conventional implicit arc-length method. It is drawn that EFG quasi-static explicit buckling analysis presents the same accurate results as implicit finite element solution, but is without convergence problem and of less-consumption of computing time than FEM.
