Evaluation of Residual Stress Effects in Aft Pressure Ring Frame of a Royal Australian Air Force P-3C Maritime Patrol Aircraft

Evaluation of Residual Stress Effects in Aft Pressure Ring Frame of a Royal Australian Air Force P-3C Maritime Patrol Aircraft

K. Walker, M. Ryan, J. Ayling

Abstract. Aft pressure bulkhead ring frames on the RAAF P-3C Orion aircraft are being replaced due to in-service fatigue cracking. Installation of the new 7075-T6511 extrusion L-section circular frame requires local adjustment of the included angle at various positions around the circumference. The adjustment should be carried out under a controlled temperature in the range of 135 – 160° C. However in some recent cases the temperature was either not well controlled and/or was below that range, raising concerns about the potential for adverse residual stresses in a region already known to be susceptible to fatigue. This paper details an investigation including 3-D non-linear finite element (FE) modelling and X-Ray diffraction based residual stress measurements on representative frame segments. The FE modelling was performed with NASTRAN using 3-D solid elements. Plastic behaviour was modelled using a Ramberg-Osgood approach. The X-Ray diffraction was performed using a Proto iXRD Combo instrument with a Cobalt X-ray source and a rectangular aperture (1.0, 1.5 or 2.0 x 5.0 mm depending on the location) and also electro-polishing for depth data. Permanent resultant angles of the frame segments were also measured using a “MarSurf CD 120” contact profiler. Typically low residual stresses were found for both the within and the below specification temperature cases. The FE and measurements were in reasonable agreement giving confidence in the results. The results from this work supported a decision to clear affected aircraft for a return to service.

Keywords
X-Ray Diffraction, Finite Element Analysis, Thermal Control, P-3C Orion, Fuselage Pressure Frame

Published online 12/22/2016, 6 pages
Copyright © 2016 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA

Citation: K. Walker, M. Ryan, J. Ayling, ‘Evaluation of Residual Stress Effects in Aft Pressure Ring Frame of a Royal Australian Air Force P-3C Maritime Patrol Aircraft’, Materials Research Proceedings, Vol. 2, pp 509-514, 2017

DOI: https://dx.doi.org/10.21741/9781945291173-86

The article was published as article 86 of the book Residual Stresses 2016

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

References
1. Scholz, L., FS1117 residual stress investigation and analysis, A09-ER-003002, 2015, Airbus Group Asia Pacific.