引入材料参数的弯管中性层偏移解析模型

中性层偏移是表征管材弯曲内外侧不均匀变形程度的关键参数。基于弯管截面力矩平衡条件,建立了引入材料参数的管材弯曲变形中性层偏移解析模型,针对管材数控绕弯和压弯过程对所建模型从多个方面进行了评估,研究了不同几何和材料等管材本征参数下的管材弯曲中性层偏移规律。结果表明:应用于TA18钛管数控绕弯,发现所建解析模型与已有解析方法预测精度相当,但能考虑材料参数影响,且相较于有限元模拟,本文解析模型更接近实验结果;应用于A6063铝合金管和AZ31镁合金管压弯过程,并与Hasegawa解析方法相较,发现本文解析模型能够准确预测拉压不对称对压弯中性层偏移的影响;弯曲半径减小,弯管直径增大,中性层向弯曲内侧移动;拉压屈服强度比减小,厚向异性指数增大,中性层向弯曲内侧移动。

Analytical model of neutral layer shift in tube bending introducing material parameters

Neutral layer shift is the key parameter to feature the degree of unequal bending deformation. Based on the balance of torque, an analytical model for neutral layer shift in tube bending is established by introducing material parameters. The model is assessed from various aspects in rotary draw bending and press bending and the rules of neutral layer shift in tube bending are studied with different geometric and material parameters. The results show that:appling the model to TA18 tube rotary draw bending, it is found that the accuracy of the established model is comparable to that of existing analytical method, but the established model can reflect the influence of material parameters on neutral layer shift and is more closer to the experiment result than finite element method; applied the model to A6063 and AZ31 tube press bending and compared the results with Hasegawa method, it shows that the established model provides better prediction accuracy of neutral layer shift under tension-compression asymmetry; decreasing the bending radius or increasing the bending diameter, the neutral layer shifts inwards; decreasing the ratio of tensile strength to compressive strength or increasing normal anisotropy exponent, the neutral layer also shifts inwards.