材料期刊网

从不考虑材料冷作硬化(理想弹塑性体)与考虑冷作硬化(双线性随动硬化)两个方面对带坯在成卷、开卷、展平、塑性弯曲及回弹过程中产生的应力进行了解析分析,获得了冷弯残余应力沿厚度方向上的分布,随后对比研究了考虑硬化与不考虑硬化对冷弯残余应力分布的影响,并将理论计算结果与实测残余应力进行了对比.结果表明,理想弹塑性模型和硬化模型预测的残余应力分布形式几乎一致;成卷上存在屈服时,纵向残余应力由内外表面向板厚中心方向呈非线性分布(成卷上无屈服时呈线性分布),横向残余应力呈近似线性分布;在变形外区主要为残余拉应力(横向残余应力在外侧有极小部分受压区),内区主要为残余压应力(横向残余应力在内侧有极小部分受拉区);横、纵向残余应力最大值均在中性层位置;研究结果与试验测量结果基本一致.

From two aspects that considering the strain hardening(bilinear kinematic hardening)and without consider-ing the strain hardening(elastic-perfectly plastic body),to the current study analyzed the stress that were produced in coiling,uncoiling,flattening,bending and rebounding processes,and obtained the residual stress distribution along the thickness direction during the coiling-rebounding. The effect of considering the strain hardening and without considering the hardening on the residual stress distribution of cold bending is researched. The calculated results are compared with the measured residual stress. The results show that residual stress distributions that were predicted by the two prediction models is almost the same. As the yield occurred on coil,the longitudinal residual stress distribution was nonlinear along the thickness direction(when the yield did not occur on coil,the stress distribution was linear),and the horizontal residu-al stress distribution was linear. The residual stress was mainly tensile stress from outer surface to neutral layer(horizon-tal residual stress had a very small compression area at the outside of deformation zone),and it was the compressive stress from inner surface to neutral layer(horizontal residual stress had a very small tension area at the inside of deforma-tion zone). Both horizontal residual stress and longitudinal residual stress had the maximum value on the neutral layer. The calculated results agreed with the experimental results.