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采用弹塑性大变形热力耦合有限元法理论,应用有限元仿真软件ABAQUS,建立了汇气管热模拔有限元模型,研究了直径Φ508 mm、壁厚18 mm汇气管热模拔成形工艺过程。重点分析了不同温度场下热模拔成形过程中汇气管的应力应变及形变位移,得到了热模拔成形工艺最佳的温度场。研究分析表明:对于低碳钢汇气管,一般热拔制成形的最佳温度场控制在1000℃左右;拔制过程中,加热拔制区域的材料的塑性变形符合材料塑性行为的三个特征:初始屈、塑性应变增长和塑性强化;拔制成形后,管件的最大残余应力出现在拔制椭圆孔短轴附近,但都满足低碳钢的失效强度。最后,对比有限元模拟结果与实验结果获得了很好的一致性,验证了模拟的可行性。
The finite element method of elasto-plastic large deformation and thermal coupling was used. The finite element simulation software ABAQUS was used to establish the hot-drawing and drawing finite element model of the exhaust manifold. The hot-drawing and drawing process of the exhaust manifold with the diameter of Φ508 mm and the thickness of 18 mm was studied. The stress-strain and displacement of the manifold in the process of hot-die drawing are analyzed emphatically, and the best temperature field of the hot-die drawing process is obtained. The research shows that the optimal temperature field for hot drawing is about 1000 ℃ for the mild steel tube, and the plastic deformation of the material in the heated region during drawing is in accordance with the three characteristics of the plastic behavior: Initial buckling, plastic strain increase and plastic strengthening. After drawn forming, the maximum residual stress of the pipe appears near the short axis of the drawn elliptical hole, but all meet the failure strength of low carbon steel. Finally, the results of the comparative FEA and the experimental results obtained very good agreement, and verified the feasibility of the simulation.