Mechanical Modeling of Braided Neurovascular Flow Diverters using a Beam-to-Beam and Beam-to-Surface Contact Formulation

Abstract

Braided neurovascular flow diverters are widely used for the endovascular treatment of intracranial aneurysms, where their mechanical response and final deployed configuration are governed by the interaction of many slender, interwoven wires. Accurate numerical modeling of these devices is essential for analyzing their structural behavior during deformation occurring in compression or deployment. This work presents a structural-mechanics-based modeling framework and finite element formulation for the numerical simulation of braided flow diverters. The individual wires are modeled using geometrically exact Simo--Reissner beam theory, allowing a consistent description of large rotations and curved reference configurations. Mechanical interactions between individual wires are described by a beam-to-beam contact formulation, while the interaction with surrounding tubular structures, such as microcatheters, is captured by a beam-to-surface contact formulation. A flexible parametric description of interwoven braided flow diverter geometries is introduced, enabling systematic control of geometric design parameters such as wire count, braiding angle, device length, and radial interweaving pattern. The proposed framework is assessed by means of three representative validation cases from the literature. A tensile test is considered to investigate the length--diameter relation and axial force response of the device, while a radial compression test is used to study the pressure--diameter behavior. Finally, a stepwise compression example is used to evaluate geometry-sensitive quantities, including local wire distance, pitch angle, porosity, and metal coverage ratio. Rooted in structural mechanics and contact mechanics, these examples provide a systematical validation setting for the proposed modeling framework and its application to the mechanical analysis of braided flow diverters.