非对称截面梁纯弯曲时几何中心层与应变中性层不重合，传统弯曲回弹理论分析方法无法准确计算应变中性层位置，使非对称截面梁弯曲零件的展开弧长和弯曲回弹后的曲率计算出现显著偏差。小曲率平面弯曲弹复理论在任意截面梁平面弯曲情况解析分析中具有独特优势。以槽钢纯弯曲为例，通过小曲率平面弯曲弹复理论计算非对称截面梁纯弯曲时的应变中性层及弯曲回弹后的曲率，并与实验数据相比较，结果较为吻合，可以达到精密加工的精度要求。通过对槽钢纯弯曲时中性层偏移率的分析可知，中性层相对偏移率与截面几何特征、材料性能、初始曲率、弯曲曲率等因素紧密相关，且均为非线性关系。该理论分析结果对非对称截面型钢的精确弯曲和矫直具有重要的工程应用价值。%The geometric center layer of the asymmetrical cross⁃section beam doesn′t coincide with the strain neutral layer under pure bending.The exact place of strain neutral layer can′t be accurately calculated by utilizing the traditional theory.Therefore,the calculation of the asymmetrical cross-section beam bending parts′expansion arc length and the curvature after pure bending spring back appear significant deviation.The spring back theory of small curvature plane bending has unique advantages in the analytical analysis of any cross⁃section beam plane bending.As an example,the pure bending of channel steel is studied to calculate the strain neutral layer and the curvature after spring back by utilizing the spring back theory of small curvature plane bending.The theoretical calculation results are consentaneous compared with the experimental data. The calculation accuracy can achieve the accuracy requirement of precision machining.The analysis results of the channel steel pure bending show that the relative offset rate of neutral layer is closely related with the cross⁃section geometry features,the material properties,the initial curvature and bending curvature. All of them have non⁃linear relationship. The theoretical results have important engineering value in the precise bending and straightening of asymmetric cross⁃section steels.
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