Mechanical Response of Mesh Materials

Viscous type damping from viscoelastics is one of the most largely adopted and studied forms of damping. However, there are some harsh environments such as outer space where viscoelastic materials are not favourable due to extreme conditions such as high and low temperatures, corrosive environments, exposure to vacuum and radiation from cosmic rays. In all of these cases, frictional (also called Coulomb or Coulombic) dampers pose as a valid alternative, thanks to the advantage of a higher resistance to temperature effects and a large applicability to different conditions, this being only limited by the properties of their constitutive materials. Because of these advantages, Coulomb dampers have been largely adopted in many applications and they are available in several different configurations. This thesis focuses on a specific type of friction material that is referred to by the author as plain-weave mesh material (PWMM), which consists in a highly ordered structure composed of interwoven wires where the mutual frictional contact at the numerous intersections generates the energy dissipation responsible for damping. Their stiffness and damping behaviour is investigated through an in-depth finite element (FE) analysis and a set of analytical models is developed to predict the mechanical response to tension, in-plane shear and out-of-plane bending. These mathematical models are compared to the numerical results for validation and a general good agreement is observed between them for a wide range of displacement. A reduced finite element model is developed, based on these theoretical formulations which are exploited to calculate the effective properties of the material. This model can be implemented in a FE code for achieving a consistent reduction in computational demand. With this purpose, based on the reduced model, a concept software is developed in a MATLAB-ANSYS integrated environment, aimed at providing a tool to assist in the design of friction mesh dampers and structures with complex geometries and load conditions. Finally, some conceptual mesh damping devices are proposed and discussed as potential industrial applications, considering different geometries, materials and loads, and their hysteretic response to cyclic loading is reported.