On the use of supersonic particle deposition to restore the structural integrity of damaged aircraft structures

The paper presents a preliminary experimental study and an analysis of the potential application of supersonic particle deposition (SPD) for repairing and restoring the airworthiness and functionality of aging aircraft structures. In this work the fatigue performances of cracked metallic structures with a SPD doubler/patch under constant amplitude loading were monitored using infra-red thermography, whereas for the baseline specimen test the crack length was monitored using digital cameras. In all the cases the experimental data revealed that the baseline specimens, i.e. without an SPD patch, accrued damage more rapidly and that crack growth was significantly greater than the corresponding SPD patched panels. In the majority of tests cases the patched panels showed little evidence of damage/crack growth. A prediction of the fatigue performance of an SPD patched single edge notch coupon is made using SIF values calculated via an approximate analysis and the resultant crack length history is in good agreement with experimental data. Weight function solutions for SPD repairs to centre cracked panels are also developed and validated via three dimensional finite element analysis. The paper concludes that SPD is effective in containing damage and that the proposed analytical solution is good first approximation that can be used to calculate the associated SIF and thereby account for the effect of an SPD patch on crack growth.