胶接点焊接头拉伸声发射信号分析及其损伤模型

Analysis of Acoustic Emission Signal in The Tensile Process of Weldbonding Joint and Its Damage Model

基于Box-Behnken Design响应面法开展胶接点焊工艺试验,分别采集了胶接点焊、点焊、粘接三种接头拉伸过程的声发射信号,采用小波包对信号进行分解重构,分析了三种接头的信号特征,同时结合撞击计数历程图对焊核失效断口进行了分析,并通过累计撞击计数建立了试件的损伤模型。结果表明:三种接头在屈服阶段和断裂阶段的声发射信号较为丰富;胶层失效和焊核拔出失效可以通过声发射信号特征进行区分,其中胶层失效时其声发射信号频率主要集中在0~62.5 kHz,焊核拔出失效时其声发射信号频率主要集中在31.25~281.25 kHz;声发射撞击计数历程图可以从总体上反映焊核失效过程;建立的损伤模型可以较好地表征试件损伤状态。

The weld-bonding test was carried out based on Box-Behnken Design response surface method,the acoustic emission signals in the stretching process of weld-bonding,spot-welding and adhesive joints were collected,and the signal was decomposed and reconstructed by wavelet packet.The weld nugget failure fracture was analyzed based on the hits history diagram,and the damage models of three kinds of joints were established through the cumulative hits.The results show that the three types of joints have abundant acoustic emission signals in the yield stage and fracture stage.Adhesive layer failure and weld nugget failure can be distinguished by acoustic emission signal characteristics.And the failure frequency of the adhesive layer is mainly concentrated in 0 to 62.5 kHz.When the weld nugget fails,the frequency is mainly concentrated in 31.25 to 281.25 kHz.The acoustic emission hits history diagram can reflect the failure process of the nugget on the whole.The established damage model can better characterize the damage state of the specimen.