21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-4.8.3

DEVELOPMENT OF AN ANALYTICAL EXPRESSION AND A FINITE ELEMENT PROCEDURE TO DETERMINE THE RESIDUAL STRESSES IN BONDED REPAIRS

Callinan R. J., Tran-Cong T., Sanderson S., Walker K.
Aeronautical and Maritime Research Lab., Australia

Keywords: analytical expression, finite element procedure, residual stresses,bonded repairs

In recent years bonded repairs using boron patches have been used as a means of life extension for cracked aircraft structures. Bonded repairs are typically cured at 80-1000C for a duration of several hours. However the difference in coefficients of thermal expansion of the components may result in significant residual stresses after cooling to operating temperatures. While an analytical analysis are available for residual stresses for repaired one dimensional strips, no analytical expression exists for the case of heat conduction in a repaired two dimensional plate. In this paper a derivation of a closed form solution will be given for the direct residual stress for a circular patch on a circular plate. These closed form solutions have direct application for the design of bonded repairs to aircraft wing skins. The validation has been carried out using F.E. analysis.

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