待矫直板材板形缺陷解析表征

 目前待矫直板材缺陷类型及程度的判断仍然是依赖现场工作人员的经验，具有很大的不确定性。为了获得待矫直板材残余应变（应力）的大小及分布，根据薄板大挠度屈曲理论和最小势能原理，建立了基于浪形几何参数的反解计算模型。通过实测的浪形几何参数和预设挠曲函数，对引起边浪、中浪（肋浪）等典型的浪形缺陷的残余应变（应力）进行求解，并与实测值进行对比。结果表明，残余应变（应力）的分布与浪形几何形状相对应，但压应力宽度略小于屈曲宽度，即紧邻压应力的拉应力区也产生了挠曲；几何非线性及后屈曲强度对浪形状态的影响是显著的；求解过程与板厚无关，所需几何参数较少，便于现场应用。

Shape defect analytical characterization of pre-levelling sheet

It is very uncertain that the judgment about shape defect types and extents of pre-levelling sheet still depends on the experience of field staff at present. According to the buckling theory of thin plates with large deflection and the principle of minimum potential energy,the inverse solution method is established by using geometric parameters of shape-wave. With the method,the magnitude and distribution of residual strain and stress of pre-levelling sheet are stud-ied. Based on the measured geometric parameters of shape wave and preset bending function,the residual strain and stress of typical shape-wave,such as center wave,edge wave and quarter wave,are solved and compared with measured values. The results show that the distribution of residual strain and stress is corresponding to the geometric parameters of shape-wave,but the compressive stress width is smaller than the buckling width. It means that bending occurred in the tensile stress zone which is close to the compressive stress zone. The influence of geometric nonlinearity and post-buck-ling on the shape-wave is obvious. The solution process with less parameters is independent of thickness and convenient for field application.