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介绍了管材低频振动绕弯塑性成形的工作原理,分析了管材低频振动绕弯塑性成形过程中金属的应变-时间历程;在一维粘弹塑性本构关系的基础上,利用Matlab的符号计算推导出了管材断面圆周上各点的动态应力的显性表达式。根据所给定的振型参数和材料力学性能参数,分别得出了管材金属在低频振动绕弯条件下的动态应力-时间曲线和在不同时间时管材断面圆周上各点的应力分布曲线。分析表明,与常规绕弯塑性成形过程的应力相比,管材低频振动绕弯塑性成形时的应力至少可以降低14.8%;附加低频振动后弯曲管材断面圆周上最大应力和最小应力的差值比无振动时管材断面圆周上最大应力和最小应力的差值减小70.8%,弯曲管材断面圆周上的应力分布更均匀。
This paper introduces the working principle of low frequency vibration pipe bending plastic forming and analyzes the strain-time history of metal during low frequency vibration plastic bending process. Based on the one-dimensional viscoelastic plastic constitutive relation, The explicit expression of dynamic stress at each point on the circumference of pipe section. The dynamic stress-time curve of pipe metal under low-frequency vibration and bending and the stress distribution curve of each point on the circumference of the pipe section at different times are obtained respectively according to the given parameters of mode shapes and material mechanical properties. The analysis shows that compared with the conventional plastic bending process, the stress of low frequency vibration plastic pipe can be reduced by at least 14.8%. The difference between the maximum stress and the minimum stress on the circumference of curved pipe after additional low frequency vibration is lower than that without vibration The difference between the maximum stress and the minimum stress on the circumference of the pipe section is reduced by 70.8%, and the stress distribution on the circumference of the curved pipe section is more uniform.