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>An investigation on longitudinal residual strains distribution of thin-walled press-braked cold formed steel sections using 3D FEM technique
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An investigation on longitudinal residual strains distribution of thin-walled press-braked cold formed steel sections using 3D FEM technique
Steel sections are normally shaped via cold work manufacturing processes. The extent of cold work to shape the steel sections might induce residual stresses in the region of bending. Previously, researchers had performed studies on the influences of local buckling on the failure behavior of steel compression members which shown that failure will happen when most of the yielding has extended to the middle surface in the bend region of the sections. Therefore, these cold work methods may have major effect on the behavior of the steel section and also its load-bearing capability. In addition, another factor may play significant role in formed section's load-bearing capacity which is the longitudinal residual strain. The longitudinal residual strain raised during forming procedure can be used to define the section imperfection of the formed section and its relation to the existence of defects. Therefore, the main motivation of this research paper is to perform three-dimensional finite element (3D-FE) to investigate peak longitudinal residual strains of a thin-walled steel plate with large bending angle along member length. A 3D finite element simulation in ABAQUS has been employed to simulate this forming process. The study concluded that the longitudinal residual strain at the section corner edge was higher than those at the rest of the corner region. These strains at the edge were higher than the yield strain of the formed section which occurred due to the lack of transverse restraint. This made the plate edge tended to bend toward the normal direction when it was under a high transverse bending. This causes a significant difference in longitudinal strain at the plate edge.
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机译：钢型材通常通过冷加工制造工艺来成型。进行冷加工以使钢型材成形的程度可能会在弯曲区域引起残余应力。以前，研究人员对局部屈曲对钢制受压构件破坏行为的影响进行了研究，结果表明，当大部分屈服延伸到截面弯曲区域的中表面时，破坏就会发生。因此，这些冷加工方法可能会对钢型材的性能及其承载能力产生重大影响。另外，另一个因素可能在成型截面的承载能力中起着重要作用，这就是纵向残余应变。成型过程中产生的纵向残余应变可用于定义成型截面的截面缺陷及其与缺陷存在的关系。因此，本研究的主要动机是进行三维有限元（3D-FE），以研究沿构件长度大弯角的薄壁钢板的峰值纵向残余应变。 ABAQUS中的3D有限元模拟已用于模拟此成型过程。研究得出结论，截面拐角边缘的纵向残余应变高于拐角区域其余部分的纵向残余应变。这些边缘的应变高于屈服应变（ ε < mrow> y ） 是由于缺乏横向约束而发生的。这使得板边缘在高横向弯曲时倾向于朝法线方向弯曲。这在板边缘引起纵向应变的显着差异。
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