钻孔法测大型构件焊接残余应力试验的误差分析与优化

Error analysis and optimization of measuring residual stress of large components by drilling method

钻孔法理论体系完备,是目前最常用的残余应力测量方法,但试验参数的选择会直接影响测量结果的准确性。文中结合理论与试验研究了钻孔法测量时的贴片时间、应变取值时间对其误差的影响。首先建立了有限元模型,采用顺序热力耦合的方法计算了残余应力的分布情况,进而选取了3条残余应力水平不同的测试路径,采用钻孔法测试3条路径下不同贴片时间、应变取值时间的残余应力结果,并对结果进行回归分析,得到误差和2种因素间的数学关系。结果表明,在同等条件下,通过控制贴片时间t_(p),误差控制效果更优,当误差在10%以内时,贴片时间t_(p)选取50.31 min,应变取值时间t_(e)选取24.12 min,为该误差下的最优时间参数。文中所用方法和结论,可为地铁枕梁等大型构件及相似结构的钻孔法焊接残余应力测量提供优化方法、思路,在保证测量精度的同时大幅提高试验效率。

Drilling method is the most commonly used residual stress measurement method with complete theoretical system,but the selection of test parameters will directly affect the accuracy of measurement results.In this paper,the influence of patch time and strain value time on the error of drilling test was studied by combining theory and experiment.Firstly,a finite element model was established,and the distribution of residual stress was calculated by using the sequential thermodynamic coupling method.Then,three test paths with different levels of residual stress were selected.Drilling method was used to test the residual stress results of different patch time and strain value time under three paths,and regression analysis was conducted on the results,and the mathematical relationship between the error and the two factors was obtained.The results showed that under the same conditions,the control effect of patch time tp error was better.When the error was less than 10%,patch time t_(p) 50.31 min and strain value t_(e) 24.12 min were selected as the optimal time parameters under the error.The methods and conclusions adopted in this paper could provide optimization methods and ideas for the residual stress measurement of large structure such as subway pillow beam and its similar structure,and greatly improved the test efficiency while ensuring the measurement accuracy.