Numerical comparison of several composite bonded repairs under fatigue loading

Abstract

In this work, a numerical analysis of typical composite bonded repairs is performed aiming to establish a comparison between their performance under quasi-static and high-cycle fatigue loading. The studies include progressive damage analysis employing cohesive zone models suitable for quasi-static and high-cycle fatigue under mixed-mode I+II loading. Five repair geometries, e.g., Single-Strap, Double-Strap, Scarf, One-Stepped and Two-Stepped were analysed under three-point bending loading considering three different overlap lengths. In the quasi-static analysis, the focus was the initial stiffness, peak load and the corresponding displacement. Fatigue studies were executed under load control and under displacement control aiming to determine the fatigue lives. A final research addressed two of the embedded repairs, Scarf and Two-Stepped, reinforced with a bonded patch, which was verified to improve significantly fatigue resistance, especially in the case of the Scarf repair.