Abstract:According to disbond of damaged metallic structures bonded with composite patches, a three dimensional
finite element analysis model was developed for the composite repairs, which conforms with the results of experienced
formula. The disbond model is also developed by the basic model, and equivalent distance was proposed for
analyzing the effects of disbond with different sizes and positions. The result shows that the large disbond is more effective
than little one, there is a strength sensitive zone near the crack tip and it is determined by crack length.