冷弯残余应力场分析

ANALYSIS OF COLD-FORMED RESIDUAL STRESS FIELD

将冷弯加工过程分解成加载 (塑性变形 )和卸载 (回弹 )两个过程 ,并分别求解得出每个过程中的应力场。通过将两个过程中分别产生的应力场迭加 ,得出构件中的冷弯残余应力值。分析所得结果与现有的研究成果有明显的区别 :纵向残余压应力沿板厚方向的分布 ,表现为自内壁向中性层增长。这种纵向残余应力分布不同于现有文献提出的线性分布 ,对结构稳定性较为不利 ,使弯曲区的板在外荷载作用下的有效厚度明显地减小。弯曲区的外壁纵向残余拉应力值略大于内壁上的纵向残余压应力值。冷弯残余应变计算值与实测值是相当的。

It is pointed out that a cold-formed processing consists of plastic deformation and elastic recovery.We can get residual stress of cold-formed member through adding stress field produced by each course.There are clear differences in distribution of residual stress between the existing research and that by the analysis.A vertical residual stress is distributed along thickness of slab,displaying that residual stress is increasing from inside layer to neutral layer.It is pointed out in the existing literatures that residual stress is linear distribution that is disadvantageous to stability of structure,because it can clearly reduce effective thickness of slab in bended zone under outer load.Vertical residual tensile stress of outer layer in bended zone is slightly bigger than vertical residual compressive stress of inside layer.The calculated result of cold-formed residual strain is equivalent to that of field measurement.