铝合金电阻点焊熔核截面反演成像

Inversion imaging of nugget cross-section in aluminum alloy resistance spot welding

将反演理论及正则化方法用于熔核横截面电流反演成像,以反演图像直观判断焊点质量,扩大铝合金电阻点焊在对焊点质量要求较高领域中的应用.首先,建立熔核截面电流分布和周围磁感应强度关系的正演模型,并通过试验验证模型的可靠性;其次,建立反演模型,通过数值试验验证反演模型的可行性;最后,点焊成像试验,将测量的磁场信号反演为熔核截面的电流分布信息,并以图像形式显示.结果表明,反演图像反映了熔核截面电流分布特点,能够反应熔核质量的好坏,可以作为判断熔核质量的依据;正则化参数的选择影响反演图像的质量,过大或过小,反演图像都将偏离实际情况.

Inverse theory and regularization method are used to the current inversion imaging of nugget cross-section. The inversion image can be used to evaluate spot weld intuitively, which meets to the requirements of higher weld quality. Firstly, the forward model which describes the relationship between the current distributions of nugget cross-section and magnetic field was established, and its reliability was verified by experiments. Secondly, the inversion model was established and the numerical experiments were conducted to verify correctness of the inversion model. In the end, different current values were chosen for the resistance spot welding experiments, and then the collected magnetic signals were transformed into current signals, which were displayed in the form of image. Experiment results show that the inversion image can describe the characteristics of nugget cross-section current distribution and reflect the quality of nugget, but regularization parameters impact the accuracy of inversion image which will remove from the real one if the parameter is too large or small.