基于内聚力模型的气波机振荡管304对接钎焊接头拉伸强度研究

Research on Tensile Strength of 304 Butt Brazed Joint of Oscillating Tube of Gas-Wave Machine Based on Cohesive Zone Model

气波机核心部件振荡管采用钎焊连接,钎焊接头拉伸性能对气波机结构强度具有重要影响。为了对钎焊接头界面裂纹扩展过程进行探究,笔者针对气波机振荡管钎焊结构,制备304对接钎焊接头试样进行拉伸试验,并对拉伸断口进行形貌分析,断口处表现为韧性断裂;基于内聚力模型,开发了VUMAT子程序,进行了有限元模拟分析。模拟断裂载荷为5 039 N,试验值为5 242 N,2者误差为3.9%,验证了模拟的准确性,结果表明内聚力模型可以较好地模拟气波机振荡管钎焊接头的裂纹萌生与扩展过程。在此基础上研究焊缝缺陷对钎焊接头断裂载荷的影响,发现缺陷处内聚力单元损伤速率加快,引起断裂载荷显著下降。

The core components of the oscillating tube are brazed,and the tensile property of the brazed joint has an important influence on the structural strength of the gas-wave machine.In order to investidate the process of interfacial crack propagation of brazed joint,according to the brazed structure of the oscillating tube of the gas-wave machine,the tensile test of 304 butt brazed joint sample prepared was carried out,and the fracture showed ductile fracture by analyzing the tensile fracture morphology.Based on the cohesion model,the VUMAT subroutine was developed and finite element analysis was carried out.The simulated fracture load was 5039 N,the test value was 5242 N,and the error of both was 3.9%,which verified the accuracy of the simulation.The results show that the cohesion model can well simulate the crack initiation and propagation process of the brazed joint of the oscillating tube of the gas-wave machine.On this basis,the effect of weld defects on the fracture load of brazed joint is studied,and it is found that the damage rate of cohesive force unit at the defect is accelerated,which results in a significant decrease in the fracture load.