Scheme showing the geometry of rotation shear in the development of a kink band. The direction defined by ĥ (or φ) is invariant and of no longitudinal strain. Segments in the ê₁-direction undergo a rotation ψ inside the kink band but do not undergo changes in length. Lines marked K-P are the kink planes (or boundaries of the kink band). Point Q of the undeformed configuration is transformed into point q of the deformed configuration.