Lyapunov Exponent And Correlation Dimension Analysis Of Current In GMAW Welding

The nonlinearity in GMAW process determines its chaotic characteristics, it’s highlyvalued at home and abroad that how to turn these characteristics applied to the WeldingEngineering and how to reflect the inherent nature of information in welding process throughthese characteristics. In the study of Chaos theory, Lyapunov exponent and Correlationdimension are major quantitative analysis indexes in chaos researching of dynamical system.This text emphasized to introduce the significance, definition and various calculation methodsof these two indexes, hope to probe the chaotic characteristic of GMAW process by analyzingthese two indexes.They are all signs of identifying Chaos, system stability and complexity that Thenumeric value of the biggest Lyapunov exponent an Correlation dimension, do they positiveor negative and if they are integer or not. In this paper we use phase space reconstruction toanalyze the current signal time sequence in GMAW by calculating Lyapunov exponent andCorrelation dimension. We also change welding voltage, welding current and gas flow rate todiscuss the chaotic characteristic of arc welding under different parameters.Studies show that chaos in GMAW welding process exists not only in short circuittransfer, but also in droplet transition and spray transfer. On this basis, we further study thevariation of the biggest Lyapunov exponent and Correlation dimension under differentparameters. The biggest Lyapunov exponent and Correlation dimension can be used as thebasis for evaluating welding process stability. It means the smaller the two indexes are, thewelding process is more stable and welding parameters are more appropriate. The criterionprovides theoretical basis of the identification of chaos, which can be used in process optimization experiments for welding parameters selection and monitoring the stability of thewelding process. This paper supplies a certain foundation for introducing these two chaoticindexes and their calculation methods into the field of Welding Engineering in the future.