Computation of the Stress Intensity Factor in Bonded Repairs to Acoustically Fatigued Panels

摘要

The application of bonded repairs to structures subject to acoustic fatigue is investigated, with a view to developing simple solutions suitable for engineering applications. Acoustic fatigue is caused by a random response of a structure due to time varying pressure waves from engine and/or aerodynamic sources. For vibration problems the use of damping in repairs will reduce the amplitude of vibration and hence the stress intensity factor in the cracked structure. To assess the viability of the composite bonded repairs subject to acoustic fatigue new analytical tools are needed. In this paper the use of a simplified dynamic analysis combined with crack-bridging theory allows the influence of damping to be assessed. This theory is adapted to panels with various edge support conditions with good results. Validation of this work is carried out using a Finite Element (F.E.) analysis in which three-dimensional brick elements are used to model the plate, adhesive and boron patch, and use is made of the power spectral density capability of the NASTRAN program.