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DETECTION METHOD OF SPOT WELDING BASED ON MULTI-INFORMATION FUSION AND FRACTAL 被引量:3
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作者 LIU Pengfei SHAN Ping +2 位作者 LUO Zhen SHEN Junqi QIN Hede 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2008年第6期76-81,共6页
A novel detection method of support vector machine (SVM) based on fractal dimension of signals is presented. And models of SVM are made based on nugget size defects of spot welding. Classification using these traine... A novel detection method of support vector machine (SVM) based on fractal dimension of signals is presented. And models of SVM are made based on nugget size defects of spot welding. Classification using these trained SVM models is done to signals of spot welding. It is shown from effect of different SVM models that these models with different inputs. In detection of defects, these models with inputs including sound signal have a high percentage of accuracy, the detection accuracy of these models with inputs including voltage signal will reduce. So the SVM models based on fractal dimensions of sound are some optimal nondestructive detection ones. At last a comparison between SVM detection model and ANNS detection model is researched which indicates that SVM is a more effective measure than Artificial neural networks in detection of nugget size defects during spot welding. 展开更多
关键词 Multi-information fusion Support vector machine box counting dimension DETECTION Spot welding
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Identification of acoustic emission signal in aluminum alloys spot welding based on fractal theory 被引量:1
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作者 罗震 罗保发 +2 位作者 单平 邹帆 高战蛟 《China Welding》 EI CAS 2007年第3期51-55,共5页
The acoustic emission signal of aluminum alloys spot welding includes the information of forming nugget and is one of the important parameters in the quality control. Due to the nonlinearity of the signals, classic Eu... The acoustic emission signal of aluminum alloys spot welding includes the information of forming nugget and is one of the important parameters in the quality control. Due to the nonlinearity of the signals, classic Euclidean geometry can not be applied to depict exactly. The fractal theory is implemented to quantitatively describe the characteristics of the acoustic emission signals. The experiment and calculation results show that the box counting dimension of acoustic emission signal, between 1 and 2, are distinctive from different nugget areas in AC spot welding. It is proved that box counting dimension is an effective characteristic parameter to evaluate spot welding quality. In addition, fractal theory can also be applied in other spot welding parameters, such as voltage, current, electrode force and so on, for the purpose of recognizing the spot welding quality. 展开更多
关键词 acoustic emission signal spot welding box counting dimension aluminum alloy
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Analysis of Acoustic Emission Signal by Fractal Theory in Aluminum Alloy Spot Welding
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作者 罗震 董安 +1 位作者 单平 邢志东 《Transactions of Tianjin University》 EI CAS 2007年第3期186-190,共5页
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
关键词 aluminum alloy spot welding box counting dimension welding quality LABVIEW
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Analyzing Rotor Rotating Error by Using Fractal Theory
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作者 WANGKai LIYan 《International Journal of Plant Engineering and Management》 2004年第4期236-240,共5页
Based on the judgement of fractional Br ow nian motion, this paper analyzes the radial rotating error of a precision rotor. The results indicate that the rotating error motion of the precision rot or is characterized... Based on the judgement of fractional Br ow nian motion, this paper analyzes the radial rotating error of a precision rotor. The results indicate that the rotating error motion of the precision rot or is characterized by basic fractional Brownian motions, i.e. randomicity, non -sequencity, and self-simulation insinuation to some extent. Also, this paper calculates the fractal box counting dimension of radial rotating error and judges that the rotor error motion is of stability, indicating that the motion range of the future track of the axes is relatively stable. 展开更多
关键词 fractional Brownian motions variance rad ial rotating error fractal box counting dimension
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