钢管弯制过程有限元仿真及断裂原因分析

Finite element simulation and crack reason analysis of steel pipe bending process

针对某金属结构公司在钢管弯制过程中出现的个别钢管断裂现象进行研究,根据现场钢管弯制工艺和工序的情况描述,采用非线性有限元软件Marc对钢管的多工位弯制过程进行模拟仿真.以最恶劣的情况即曲率最大的胎具进行多工位弯制,仿真结果显示6个工位的连续弯制过程最大应力为552 MPa,没有达到材料的抗拉极限626 MPa,该弯制过程不会引起钢管强度失效.模拟钢管多种曲率胎具弯制下的应力应变分布情况和回弹后残余应力应变情况.仿真结果表明,弯制此种钢管最大曲率的圆弧时,钢管上的最大应力为542 MPa,小于材料的抗拉强度626 MPa;最大塑性应变为0.031,小于材料允许的最大伸长应变0.2.经过模拟仿真分析,该公司采用的弯制工艺不会引起材料强度失效断裂.引起钢管弯制断裂的原因为个别材料夹杂或气孔造成的小概率事件.

The bending processes of a steel pipe of a steel structure company are simulated by finite element method. According to the bending processes and operations applied in the field, the finite element model of multiple operations and stations is built on the non-linear finite element model software platform Marc. The worst conditions when the curvature is the best are calculated, and the results show that the maximum von Mises stress is 552 MPa during six continuous operations, which do not reach the tensile strength （626 MPa） of the steel material, the cracking is not due to the bending. In addition, further bendings under different curvatures are done. The results of the maximum curvature show that the maximum von Mises stress is 542 MPa, which is smaller than the tensile stress; the maximum strain is 0.031, which is much smaller than the tensile rate O. 2. The finite element model simulation verifies that the reason for cracking is not due to bending. The crack reason is perhaps due to the unexpected mixtures and pore in some individual steel pipe.