An unstructured quadrilateral mesh generation algorithm for aircraft structures

Because commercial aircraft are built with thin-walled structures, their structural performance is well-modeled using shell-element meshes. However, creating these meshes for the full aircraft configuration can be challenging and presents a bottleneck in the design process, especially in a configuration-level design space. This paper presents an algorithm that automatically creates unstructured quadrilateral meshes for the full airframe based on just the description of the desired structural members. The approach consists in representing each node in the mesh as a linear combination of points on the geometry so that the structural mesh morphs as the geometry changes, as it would, for example, in aerostructural optimization. The algorithm divides the aircraft skin into 4-sided domains based on the underlying B-spline representation of the geometry. It meshes each domain independently using an algorithm based on constrained Delaunay triangulation, triangle merging and splitting to obtain a quadrilateral mesh, and elliptical smoothing. Examples of fullconfiguration structural meshes are provided, and a mesh convergence study is performed to show that element quality can be maintained as the structural mesh is refined. The algorithm is available as part of the open-source aircraft geometry tool suite, GeoMACH.