Crack growth monitoring in corrosion-fatigue tests using back face strain measurement technique

Corrosion-fatigue crack growth tests are known to be considerably time consuming, particularly due to low loading frequencies which often result in several months of testing. This study focuses on development of a material and load dependent numerical model which correlates back face strains with crack lengths for standard compact tension, C(T), specimen geometry. To validate numerical predictions, calibration fatigue crack growth tests were conducted in air on C(T) specimens made of S355 steel, which is widely employed in offshore wind industry. The results obtained from these tests at different load levels have been compared with those predicted from the numerical model. Characterization of isotropic-kinematic hardening behaviour for the material adopted was carried out using the data available in the literature. The numerical model presented in this work has proven to generate accurate estimates of crack length in corrosion-fatigue tests. This model can be used in future experimental test program on S355 steel without needing to obtain experimental correlations between crack length and back face strains from calibration tests performed in air.