Study On Fault Diagnosis Of FDM 3D Printing Process Based On HSMM And EEMD

The thesis comes from the national fund project"Study on the theory and method of mon-itoring FDM 3D printing based on acoustic emission".In this paper,the failure mechanisms of product and synchronous belt tooth were studied.Based on this,using acoustic emission technol-ogy as a means of signal detection,the fault diagnosis method of FDM 3D printing process based on HSMM and EEMD was proposed.The main contents of this paper are as follows:(1)Studying bonding mechanism of the filament in FDM 3D printing and analyzing the de-lamination damage mechanics model in FDM,Combining both of them to explain fault evolution process of product printed.The failure mechanism of synchronous belt tooth was explored through analyzing stress model of the synchronous belt and the characteristics of the FDM 3D printer.In this paper,the acoustic emission sources in the FDM 3D printing were analyzed,and the avail-ability of acoustic emission technique in the FDM 3D printing was verified by the actual acoustic emission signals.(2)The basic principles and algorithms of the EMD were studied,and the defects of the EMD method were analyzed.The basic principles and algorithms of the EEMD were studied,and the anti-aliasing of the EEMD was analyzed using fault acoustic emission signals.The correlation coefficient method was used to screen the effective IMF components from EEMD,and the energy of the effective IMF components were extracted to be the vectors.The effectiveness of the EEMD method used in FDM 3D printing process was proved by analyzing the vetors.(3)The basic principles and algorithms of the HSMM were studied.To improve the robust-ness and stability of the HSMM,the problem of training HSMM with multiple observation se-quences was studied.The fault diagnosis method based on HSMM and EEMD was proposed to detect the faults in FDM 3D printing.The HSMM program was implemented in Java language.(4)The multi-group comparison test was designed to study the fault diagnosis method pro-posed in the paper.The results of test showed that the fault diagnosis method had a high diagnostic accuracy and could achieve the desired results.