Measuring of Strain and Displacements in Welded Joints Subjected to Tensile Load Using Stereometric Methods

During the experimental testing of a welded joint, made of steel P460NL1, complete strain and displacement fields, which provide full insight into the behaviour of a welded joint under tensile load, were obtained using an optical stereometric measuring method. Optical stereometric method involved the application of digital image correlation. Presented in this paper are the strain and displacement for various load levels are shown, along with the behaviour of the welded joint as a whole. As a result of this approach, concrete and accurate values of the observed strain field as a whole can be compared directly, rather than as chosen representative parts that would be tested using a strain gauge in a single position, and provide a more detailed insight into the behaviour of the tested joint. With the aid of images obtained using cameras, the development of strain over time can be monitored, while pointing out the critical parts of a welded joint, allowing the determining of potential locations with increased stress intensity factor.