Investigation of effective parameters on composite patch debonding under static and cyclic loading using cohesive elements

• A high cycle fatigue de-cohesive constitutive law is used for debonding investigation of composite patch–cracked panel interface.
• Effects of material, width, and thickness of patch, and bonding strength on progressive damage of bonding interface are investigated.
• A patch material with larger elastic modulus, thickness and adhesive thickness leads to more damages in the adhesive bound-line.
• By increasing the adhesive strength and patch width, the de-bonding and crack growth rate of the panel are decreased.

The major addressed issue in this paper is investigation of impressive parameters on initiation and propagation of debonding in the adhesive layer when it occurs concurrently with the growth of an initial crack in a single-side repaired aluminum panels by composite patches under cyclic loading. Using the softening behavior of thin layer solid like interface elements, debonding is modeled between the composite patch layer adjacent to the aluminum panel as a function of loading condition and stress field. A user element routine and two damage model routines were developed to include the interface element and to simulate the distribution of damage in adhesive layer under static and cyclic loading. Fatigue crack growth in aluminum panel was also modeled using a simple approach developed by the authors. It is shown that, it is possible to decrease the debonding propagation by implementing appropriate composite patch and adhesive dimensional and material properties.