Non-contact monitoring of fatigue crack growth via digital image correlation method

Abstract

The aim of this paper is to present the possibilities of application of digital image correlation (DIC) method in measuring crack propagation in a welded joint specimen with a notch. For this purpose, specimens were taken from butt welded plates, made of P460NL1 micro-alloyed steel, which is typically used in manufacturing of pressure vessels, such as pipelines and storage tanks. Solid wire FILTUB 12M was used as additional material for the welded joints. Fatigue pre-cracking of threepoint bending specimens was done on the hydraulic testing machine 1332 INSTRON-100 kN by introducing fatigue crack in the weld metal region of the welded joint. After that specimens were analysed using digital image correlation software ARAMIS. This optical measuring system, in addition to the software also includes two cameras, which were used to record images of crack propagation in three dimensions, as well as the strain field.