This article reviews fretting wear damage in industries and in the contact mechanics of coated systems. Micro-slip motion resulting in fretting damage is discussed along with major experimental factors. The experimental factors, including normal force, relative displacement, frequency and medium influence are directly compared. Industrial solutions to reduce fretting damages are then discussed. The contact mechanics of a coated system are reviewed to quantify stress states in a coating layer and the substrate. Finally, a literature review on simulation for fretting is carried out. This review study provides useful methods and practical solutions to minimize fretting wear damage.

Cross structures have been well adopted as load bearing structures due to their excellent mechanical properties. A two-dimensional violet phosphorene compound composed of cross sub-nano rods has been demonstrated to have extremely high deformation resistance. The two-dimensional (2D) Young's modulus of monolayer violet phosphorene, reflecting the intrinsic deformation properties of violet phosphorene, has been deduced to be 1512 ± 76 N m⁻¹ by nano-indentation using an atomic force microscope. The 2D Young's modulus of monolayer violet phosphorene is 4.4 times as high as that of graphene and much higher than those of other reported 2D nanostructures. The extremely high bending stiffness of violet phosphorene has also been demonstrated to originate from its staggered cross structures.