Application of vibroacoustic signals to evaluate tools profile changes in friction stir welding on AA 1050 H24 alloy

Abstract

This paper presents a study to evaluate the effect of the tool profile on friction stir welding (FSW) process in the aluminium AA 1050, using vibroacoustic signals. The vibroacoustic signals in Z and Y directions have been acquired by the AE instrument NI USB-9234. The characterisation in time and frequency domains and the statistical analysis of vibroacoustical signal have been carried out in order to correlate them with the design of two different tools. Statistical and temporal parameters of discomposed vibroacoustical signals using wavelet transform have been used for filtering vibration signal to eliminate the noise of the FSW machine and the extraction features of them. The analysis has confirmed that the vibroacoustical signals were significantly affected by changes in the tool profiles. Finally, it has been demonstrated that signals generated by this process can be effectively used to characterise the changes on tool design.

Keywords:

• Friction stir welding
• Tool profile
• Vibration
• Signal processing
• Wavelet transform
• Aluminium

This paper has been partially supported by the project of the Spanish Government DPI2011-25007, ‘Friction stir welding of dissimilar materials. Characterization by acoustic emission techniques and artificial intelligence’.