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ABSTRACT. In this research activity static tensile and fatigue tests have been carried out to investigate the mechanical behavior of specimens made of high strength steel AH36, widely used in shipbuilding. It was also analysed the effect of stress concentration due to the presence of circular holes with diameters from 5 to 10 mm. The digital image correlation technique was applied to detect the displacement pattern during the static tests. The versatility of this method makes it possible to evaluate some of the phenomena of damage and local heterogeneities which could be hardly observed. The DIC (Digital Image Correlation) technique, applied on the specimens with a passing hole of different diameter, enabled us to analyze the displacements around the hole.
The displacement field was compared with that obtained from finite element analyses and with the temperature pattern detected by the thermographic technique. The highly stressed volume, defined as the material volume subjected to at least 95% of the maximum stress value, was evaluated by theoretical and numerical analysis.
Then fatigue tests were conducted on the different types of investigated specimens to evaluate the fatigue strength reduction for the presence of passing holes and correlate it with the corresponding values of highly stressed volume.