Shear-driven strain localization has been observed in a wide variety of materials and may take the form of shear bands or kink bands. Based on observations of kink bands in plastically anisotropic metallic nanolaminates and single crystal metals, we posit that, for the specific case of isochoric deformation, the kinematics of kink band formation are indistinguishable from those of plane strain shear band formation. The only distinction between shear bands and kink bands in these systems would then be that kink bands ‘lock up’ at a particular value of material rotation while shear bands may progress to arbitrarily high strains. In order to investigate whether strong material anisotropy is sufficient to arrest shear localization at a geometry that matches the classic kink band geometry, we model the development of a band of simple shear within an anisotropic perfectly plastic material. The resulting analytical model provides the stress state needed to maintain the kinematics of simple shear as a function of material anisotropy, deformation band orientation, and shear strain (or equivalently, material rotation). It is found that plastic anisotropy can promote either kink band or shear band formation depending on the loading orientation. When the deviatoric stress is positive parallel to the plane of anisotropy, shear localization may progress without bound and a shear band is produced. When the deviatoric stress is negative parallel to the plane of anisotropy, shear localization is arrested after a certain material rotation, resulting in a kink band. Examination of the requisite applied stress state during kink band formation provides an explanation for the experimentally-observed ‘lock up’ geometry. Solutions for the band boundary inclination angle are obtained and used to provide bounds on permissible band angles for both shear bands and kink bands.

剪切驱动的应变局部化已在多种材料中观察到，并可能采用剪切带或扭结带的形式。基于对塑性各向异性金属纳米层压板和单晶金属中扭结带的观察，我们认为，对于等速变形的特定情况，扭结带形成的运动学与平面应变剪切带形成的运动学没有区别。在这些系统中，剪切带和扭结带之间的唯一区别是，扭结带会“锁定”在特定的材料旋转值，而剪切带可能会发展到任意高应变。为了研究强材料各向异性是否足以将剪切局部化限制在与经典扭结带几何形状匹配的几何形状上，我们模拟各向异性完美塑性材料中简单剪切带的发展。所得的分析模型提供了维持简单剪切运动学所需的应力状态，该运动是材料各向异性，变形带取向和剪切应变（或等效地，材料旋转）的函数。已经发现，取决于负载取向，塑性各向异性可以促进扭结带或剪切带的形成。当偏应力平行于各向异性平面为正时，剪切局部化可能会无限制地进行，并产生剪切带。当偏应力平行于各向异性平面为负时，在材料旋转了一定时间后，剪切局部化将被阻止，从而导致扭结带。扭结带形成过程中必要的施加应力状态的检查为实验观察到的“锁定”几何结构提供了解释。获得带边界倾斜角的解，并将其用于为剪切带和扭结带提供允许带角的界限。