The relation between acoustic emission signal and nugget during aluminum alloy spot welding was investigated in order to evaluate spot welding quality. Due to the nonlinearity of the signals, fractal theory was utiliz...The relation between acoustic emission signal and nugget during aluminum alloy spot welding was investigated in order to evaluate spot welding quality. Due to the nonlinearity of the signals, fractal theory was utilized to quantitatively describe the characteristics of the signals instead of classical Euclidean geometry which cannot describe the acoustic emission signal accurately. Through experiments and computing, the box counting dimension is found distinct from other acoustic emission signals and is a better approach to discriminating weld nugget stages. Results show that fractal dimensions increase from 1.51 to 1.78,and they are related to nugget areas added from non-fusion to over-heated nugget. And the box counting dimension can effectively evaluate the quality of the nugget in the spot welding and can be aoolied with current, displace, and other soot welding parameters.展开更多
基金Supported by National Natural Science Foundation of China(No.50575159)Ministry of Education of China(No.20060056058 ,No.106049)Natural Science Foundation of Tianjin(No.06YFJMJC03400) .
文摘The relation between acoustic emission signal and nugget during aluminum alloy spot welding was investigated in order to evaluate spot welding quality. Due to the nonlinearity of the signals, fractal theory was utilized to quantitatively describe the characteristics of the signals instead of classical Euclidean geometry which cannot describe the acoustic emission signal accurately. Through experiments and computing, the box counting dimension is found distinct from other acoustic emission signals and is a better approach to discriminating weld nugget stages. Results show that fractal dimensions increase from 1.51 to 1.78,and they are related to nugget areas added from non-fusion to over-heated nugget. And the box counting dimension can effectively evaluate the quality of the nugget in the spot welding and can be aoolied with current, displace, and other soot welding parameters.
