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一、前言加工变形过程的应力场和应变场一般都随着构件形状和塑性区的变化而变化。在一般情况下应力分量和应变率分量是位置和时间的函数;但在某些特殊条件下,塑性区的范围保持不变,从而机动场和静力场也在变形过程中保持不变。在此情况下,应力分量和应变率分量都将与时间无关而只是位置的函数,这类过程称为定常变形过程。一般情况下,定常过程都是在非定常过程之后发生的。在非定常过程中,塑性区以及应力和应变分布规律都随时间变化,并逐步趋向于定常的分布。
I. Foreword The stress field and strain field in the process of deformation generally change with the change of the shape and plastic zone of the component. In general, the components of stress and strain rate are a function of position and time; however, the extent of the plastic zone remains constant under some special conditions so that the maneuvering field and the static field remain unchanged during the deformation. In this case, both the stress component and the strain rate component will be time-independent and only a function of position. This type of process is called a normal deformation process. In general, regular processes occur after unsteady processes. In the unsteady process, the plastic zone and the distribution of stress and strain change with time, and gradually tend to the steady distribution.