Contact Pressure And Piezoelectric Measurement In Sheet Metal Forming Process

Investigation of the tool wear controlling and evolution characteristics of contact pressure during bending and drawing process of high strength steel was performed. Plastic forming theory was applied to analyze the magnitude of the contact pressure at the die radius during the box-shaped drawing process. Finite element method was utilized to simulate the U-shaped bending channel forming process of DP780. The influence of different material parameters model on die wear was analyzed. According to the analysis results, the variable Young’s modulus model had smaller influence on the tool wear of sheet metal than constant Young’s modulus model.Meanwhile, the force-electric coupling model of finite element model was established for PVDF piezoelectric cable according to the piezoelectric properties. The relationship between electric potential of outermost layer of PVDF piezoelectric cable and applied load under small horizontal load was analyzed. The pressure-electric potential curve of PVDF the outermost layer of the cable under the primary load was analyzed. When the embedded depth of the cable is not larger than 0.5d, the output electric potential difference of PVDF film layer decreases with the increase of embedded depth; The piezoelectric cable electric potential of FVDF the outermost layers under different embedded depth was measured. Moreover, the feasibility of in-situ measurement of contact stress in half embedded piezoelectric cable on the die radius during the U-shaped bending forming process was verified. In addition, PVDF piezoelectric cable calibration device was designed, and the calibration experiment was carried out to obtain the piezoelectric coefficient of the cable. Finally, an experiment was carried out to obtain the piezoelectric properties of PVDF piezoelectric by using the designed experimental measurement device. The relationship between the electric potential and the input load was measured under the conditions of horizontal plane and half embedded PVDF piezoelectric cable.