Experimental Study of the Reduction at Crack-Tip Stress Intensity Factor KI by Bonded Patches

Patch repair of cracked structures has become a rapidly grown technology. The major function of a repair is to reduce the stress intensity factor at the crack-tip. Calculation of stress intensity factor of a repaired crack has been performed by analytical and numerical methods. However, these methods are based on simplifying assumptions regarding material behavior and repair conditions. In the present paper an experimental and an numerical determination of mode-I stress intensity factor (SIF), KI at the tip of an edge crack reinforced with bonded patches is undertaken by using the optical method of caustics and the finite element analysis (FEA). The experimental method of caustics is simple in its application and has successfully been used for the solution of a host of crack problems of engineering importance. The experimental results are compared with the corresponding one obtained by FEA. The program ANSYS 11 was used for the FEA. The cracked used plates were made of Lexan (PCBA) and the patches were made of Plexiglas (PMMA).