顺次及交叉加载方案下螺栓弹性交互作用规律

Elastic Interaction Rules between Bolts during Cross and Sequential Bolt-up Process

由于螺栓之间存在弹性交互作用,采用力矩方法逐个加载螺栓难以获得均匀一致的预紧载荷。试验研究了顺次及交叉多轮加载方案下螺栓的弹性交互作用规律。螺栓采用8根M20×1.5双头螺柱,材料35CrMoA。采用应变片和应变仪实时监控螺栓载荷,采用力矩扳手加载。结果表明,在螺栓加载过程中存在两种弹性交互作用:正作用和负作用。弹性交互作用使交叉加载和顺次加载的最终载荷分布分别呈现W形和N形。分析了正作用和负作用的规律,依据规律提出了优化的加载方案,可将弹性交互作用系数方阵[A]n×n简化为三对角阵,提高了弹性交互作用系数法的实用性。

Achieving uniform preload is difficult by tightening bolts one by one with torque controlled method because of the elastic interaction between bolts. An experimental study was presented in order to determine interaction rules in two tightening strategies： cross pattern and sequential pattern with multi - pass. The flanges were fastened together using eight M20 × 1.5 stud bolts made of 35CrMoA. Strain gauges and continuous strain readouts were used to monitor blot tensions in real time. Bolt tightening was accomplished by torque wrench. The results indicate that two types of interaction effect exist in the blot - up process ： positive effect and negative effect. The combination of the two kinds of effect makes the final load distribution as W shape in cross pattern and N shape in sequential pattern. The features of positive and negative effect were concluded. A simple interaction coefficient method with proper bolt - up process in which the elastic interaction coefficient matrix [ A ] m×n can be simplified to tridiagonal matrix were introduced.