STRAIN LOCALIZATION IN DUCTILE SINGLE-CRYSTALS
STRAIN LOCALIZATION IN DUCTILE SINGLE-CRYSTALS
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DOI：
10.1016/0022-5096(77)90001-1
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发表时间：
1977-01-01
影响因子：
5.3
通讯作者：
RICE, JR
中科院分区：
文献类型：
--
作者：
ASARO, RJ;RICE, JR
本文讨论了单滑移变形下韧性晶体的应变局部化问题。塑性流动被建模为率不敏感，和本地化，被视为从一个均匀的变形模式的一个是集中在一个狭窄的“剪切带”的分叉，被认为是可能的，只有当塑性硬化模量的滑移系统已经下降到一定的临界值ehcr，敏感的精确形式的本构关系增量剪切。我们推导了该本构律的一般形式，并在其中纳入了临界分解剪应力偏离施密德规则的可能性，并且我们表明，当偏离施密德规则时，thathr实际上可能为正。有人建议，微观力学过程，如“交叉滑移”在晶体中提供的具体情况下，应力以外的施密德应力可能会影响塑性响应，此外，有一个实验关联的本地化与发病大量的交叉滑移。因此，我们给出了具体形式的hcr的本构模型，对应于非施密德效应的交叉滑移，我们开发了一个位错模型的过程中，我们估计所涉及的参数的大小。这项工作支持的概念，局部化可以发生与积极的应变硬化，hcr> 0，和经常调用的概念，达到理想的塑性或应变软化状态的局部化可能是不必要的。
This paperis concerned with an analysis of strain localization in ductile crystals deforming by single slip. The plastic flow is modelled as rate-insensitive, and localization, viewed as a bifurcation from a homogeneous deformation mode to one which is concentrated in a narrow ‘shear band’, is found to be possible only when the plastic hardening modulus for the slip system has fallen to a certain critical valuehcr, sensitive to the precise form of the constitutive law governing incremental shear. We develop the general form of this constitutive law, incorporating within it the possibility of deviations from the Schmid rule of a critical resolved shear stress, and we show thathcrmay in fact be positive when there are deviations from the Schmid rule. It is suggested that micromechanical processes such as ‘cross-slip’ in crystals provide specific cases for which stresses other than the Schmid stress may influence plastic response and, further, there is an experimental association of localization with the onset of large amounts of cross-slip. Thus, we give the specific form ofhcrfor a constitutive model that corresponds to non-Schmid effects in cross-slip, and we develop a dislocation model of the process from which we estimate the magnitude of the parameters involved. The work supports the notion that localization can occur with positive strain-hardening,hcr> 0, and the often invoked notions of the attainment of an ideally-plastic or strain-softening state for localization may be unnecessary.