Dynamic Analysis of Brush-Seal Bristles Using an Incremental Corotational Beam and a Stick–Slip Friction Model

The dynamic behavior of brush-seal bristles governs seal performance and life. Brush-seal hysteresis and the contact and friction of the bristles have been studied extensively by experiments, by three-dimensional finite-element analysis, and more recently by models of inter-bristle friction. What remains is to combine these consistently within a reduced-order multibody analysis and to fix, on physical grounds, the parameters that such a combination requires. This work implemented, in C++ and Python within the open-source multibody system Exudyn, an incremental corotational beam with an analytic tangent stiffness and analyzed the three-dimensional large-deformation dynamics of a bristle. A stick–slip friction model treats the stick–slip transition continuously, and its two friction parameters—left to user input in commercial codes—are derived from the elastic energy of the contact point. Contact is formulated with a Lagrangian constraint at the contact point, and inter-bristle friction damping is represented by Rayleigh damping based on a measured loss factor. The implemented beam agrees with the built-in Exudyn beam to within 0.02% (tip displacement) and 0.03% (shape) and is cross-validated against a prior study at a friction coefficient of 0.3. Fixing the contact point reduces the numerical oscillation of the reaction force by about 9 times relative to re-searching it at every step, and the inter-bristle friction damping yields a dynamic response distinct from material damping alone. The friction force recorded during the analysis is a single-valued function of the elastic state of the contact, reaching the limiting friction exactly when the elastic slip reaches the derived limit, and it reverses sign between incursion and retraction.