ESTABLISHMENT OF SPRINGBACK PREDICTION MODEL FOR THE ROTARY-DRAW BENDING OF THIN-WALLED RECTANGULAR TUBE CONSIDERING VARIATION OF YOUNG'S MODULUS

Springback is one of the main defects affecting the forming precision of 3A21 thin-walled rectangular tube in rotary-draw bending process. The material hardening mode and Young's modulus influence the springback prediction greatly, while the Young's modulus changes versus plastic strain rather than a constant. Hence, the variation of the Young's modulus has been taken into account in the springback analysis to improve the springback prediction precision. Based on Von-Mises yield function and Swift isotropic hardening model, a new material constitutive model is developed considering the variation of Young's modulus. Then, a springback prediction model is established using this new constitutive law. Furthermore, the reliability of the model is validated experimentally. Comparisons between simulation results and experimental data show that the prediction model with the new constitutive law is able to predict the springback significantly more accurately.