Abstract
Cracks formed in steel plates, especially in marine and industrial structures, are considered
one of the main factors that reduce the strength and safety of structures. Effective repair of
such damage plays an important role in increasing service life and improving structural
reliability. Therefore, the present study was conducted with the aim of investigating the
performance of composite patches in repairing cracked steel plates and improving their
fracture behavior. In this research, numerical analysis was performed using Abaqus
software and the J-Integral method to examine the effect of different composite patch
characteristics on mechanical behavior. The main variables included patch material
(carbon–epoxy and glass fiber), thicknesses (0.4, 0.5, 0.6, and 1.2 mm), and fiber
orientations (0°, 45°, and 90°). Modeling and simulation were carried out for single-sided
and double-sided patches, and parameters such as Stress Intensity Factor (K), axial stress
(S22), and crack opening displacement (COD) were evaluated. The novelty of this study
lies in the systematic comparison of patch material, thickness, and fiber orientation within
a comprehensive three-dimensional analysis and in the precise evaluation of stress
reduction and crack tip deformation. The findings showed that carbon–epoxy patches had
greater efficiency than glass fiber patches in reducing the Stress Intensity Factor and crack
opening displacement. Furthermore, increasing the patch thickness and placing the fibers
at an angle of 90° relative to the loading direction produced the greatest reduction in K and
S22. In addition, double-sided patches showed better performance compared to single-sided
patches in reducing stresses. Based on the results, it can be recommended that in industrial
applications, especially in marine environments, the use of carbon–epoxy patches with
greater thickness and fiber orientation at 90° is an optimal option for repairing and
increasing the durability of cracked steel plate