基于连续损伤力学的楔横轧芯部损伤建模及预测

Modeling and Prediction of Central Damages in Cross Wedge Rolling Based on Continuous Damage Mechanics

楔横轧因存在芯部损伤累积行为而容易形成芯部疏松缺陷,准确预测芯部损伤形成条件对楔横轧轴类件高性能制造具有重要意义。开展了不同条件下的热拉伸试验,得到了影响材料损伤的主要因素;基于连续损伤力学,提出了耦合温度、应变速率和应力三轴度的损伤本构模型;开展了不同断面收缩率的楔横轧试验,标定了损伤本构模型的材料断裂阈值,并验证了损伤模型的预测精度;利用该模型预测了断面收缩率、展宽角、成形角对芯部损伤的影响规律,为参数选择提供参考。研究结果表明:温度、应变速率及应力三轴度都显著影响材料损伤行为,所建立的耦合损伤本构模型能较好地预测楔横轧芯部的损伤演化过程;楔横轧芯部损伤与成形角成反比,与展宽角和断面收缩率成正比,各参数影响程度由小到大依次为断面收缩率、展宽角、成形角。

Due to the cumulative central damage behavior in cross wedge rolling,it was prone to form central porosity defects,thus it was of great significance for high-performance manufacturing of cross wedge rolling shaft parts to accurately predict the formation conditions of central damages.The hot tensile tests were conducted under different conditions to obtain the main factors that affected material damages.Subsequently,the coupled damage constitutive models considering temperature,strain rate and stress triaxiality were proposed based on continuous damage mechanics.Furthermore,experiments on cross wedge rolling with different area reduction were conducted to calibrate the material fracture threshold of the damage constitutive model and verify the prediction accuracy of the damage model.The models were used to predict the influence laws of area reduction,spreading angle,and forming angle on central damage,which provided references for parameter selection.The results show that temperature,strain rate and stress triaxiality all significantly affect material damage behavior,and the established coupled damage constitutive models may effectively predict the evolution processes of central damages in cross wedge rolling.The central damages of cross wedge rolling are inversely proportional to the forming angle,and is directly proportional to the spreading angle and area reduction.The degree of influence of each parameters,from small to large,is in order of area reduction,spreading angle,and forming angle.