铝合金点焊电极位移时序相空间重构及混沌特征分析

以混沌理论和相空间重构方法为基础对点焊焊接过程中电极位移信号时间序列进行了特征分析,并分别对试验获得的多组点焊位移信号时间序列的最佳时间延迟τ、关联维数D、嵌入维数m及最能体现混沌特征的李雅普诺夫(Lyapunov)指数进行了定量化的计算.分析发现点焊焊接过程中电极位移信号在某些情况下具有混沌特征,并与目前采用的小波能谱分析、分形维数分析进行了比较.结果表明,信号的Lyapunov指数特征能够更加精确的反映熔核尺寸变化.

Phase reconstruction and chaotic properties analysis of signal time series of electrode displacement during Al-alloys spot welding

The chaotic theory and method of phase reconstruction were used to analyze signal time series of electrode displacement during spot welding.And some indexes such as optimal delay time, correlation dimension, embedding dimension, and Lyapunov exponent which can reflect the chaotic property of time series at utmost were estimated quantitatively from signals of electrode displacement. As a result, the chaotic properties were discovered in these time series.And the comparison were done among the three methods:energy spectrum of wavelet, fractal dimension and Lyapunov component.The results show that the Lyapunov component can reflect the change of nugget size more accurately.