Optimization of a passive aircraft arrestor with a depth-varying crushable material using a smoothed particle hydrodynamics (SPH) model

This thesis explored the viability of a depth-varying passive arrestor system for civil aircraft applications. The current technology for such arrestors involves the use of large beds of crushable aerated concrete, which will safely decelerate aircraft that overrun the runway end. The aircraft rolls through the bed, dissipating energy as the tires crush the arrestor material. Currently, such arrestors utilize homogeneous foam materials. However, a given arrestor bed must function for all aircraft serviced on the runway of interest; such aircraft can differ in size, mass, tire diameter, landing gear configuration, etc. Consequently, the arrestor must function as a one-size-fits-all (OSFA) solution, despite its passive and static nature. The question explored in this thesis was, can a non-homogeneous, depth-varying material enhance the OSFA performance?

The study developed LS-DYNA finite element (FEM) tire models for three aircraft: the B737, B747, and CRJ-200. These tires then interfaced with a numerical arrestor bed model, the properties of which were varied parametrically in an optimization study. The arrestor bed employed a Smoothed Particle Hydrodynamics (SPH) formulation, although the original research plan envisioned it as a FEM model. Several chapters outline the extensive comparison of the FEM and SPH methods, as applied to the arrestor model.

Preliminary screening compared quadratic and linear depth-varying profiles for an arrestor material, using Radial Basis Function Network (RBF) metamodeling techniques in LS-OPT. The final optimization task targeted the linear profile, which appeared to offer the most promising performance improvement. The optimization showed that the linear depth-varying material offered several advantages over a homogeneous material, including inherent geometry matching with different tire sizes, reduced performance sensitivity for smaller tires, and overall improvement of the OSFA performance.