双金属复合方形棒辊式矫直截面状态分析

Cross section state analysis of bimetallic composite square bar during roll straightening

通过对双金属复合方形棒辊式矫直过程截面状态的分析,根据弹塑性变形理论建立了双金属复合方形棒截面状态判定模型,确立了截面变形状态的边界条件。根据该模型判定双金属复合方形棒内外层金属材料达到弹性极限的先后顺序,建立了不同弯曲状态时弯矩比与弯曲曲率比的关系。与单一材料辊式矫直过程进行对比,双金属复合方形棒的截面状态可分为两类。双金属材料的截面状态与单一材料不同,双金属复合材料内外层发生塑性变形的先后顺序与内外层材料弹性极限、弹性模量和内外层厚度比有关;双金属复合方形棒在内外层结合面两侧存在应力突变,结合面两侧应力差值随着到中性层距离的增加而增加,卸载后结合面两侧残余应力差值在截面高度方向先增大后减小。

Based on the analysis of cross section state of the bimetallic composite square bar roll straightening process,the cross section state determination model of bimetallic composite square bar was established and the boundary condition of the cross section deformation state was determined according to the theory of elastic-plastic deformation.According to the model,the order of the metal materials in the inner and outer layers of the bimetallic composite square bar to reach the elastic limit was decided,and the relationship between the bending moment ratio and the bending curvature ratio in different bending states was established.Compared with the single material roll straightening process,the cross section state of bimetallic composite square bar can be divided into two categories.The cross section of bimetallic material is different from that of a single material,and the order of plastic deformation of the inner and outer layers of bimetallic composites is related to the elastic limit and the elastic modulus of the inner and outer materials and the thickness ratio of the inner and outer layers.There is a sudden change of stress on both sides of the inner and outer joints of the bimetallic composite square bar.The stress difference of the two sides of the joint surface increases with the increase of the distance to the neutral layer.After the unloading,the residual stress difference of the two sides of the joint surface increases first and then decreases in the height direction of the cross section.