In WP4, a numerical evaluation of static experiments and fatigue tests on smooth and notched samples will be performed. For this purpose, an extension of the Gurson-Tvergaard-Needleman model, proposed by Nahshon and Hutchinson, will be applied. The experimental input comes from both WP2 and WP3. The test results from WP2, using Digital Image Correlation, will provide strain hardening behaviour and anisotropy up to high plastic stranes, and also heterogeneous strain fields in complex specimens. These results allow identifying the parameters of an extended damage model. Residual stresses in the vicinity of the hole will be measured through the thickness. In order to provide detailed information about plastic deformation, damage (porosity), strain hardening and residual stresses in the steel plates after punching will be simulated.

Objectives

  • Generate computational models of the deformation, damage and failure behaviour of the sound material due to both the manufacturing process and in-service static loading.
  • Perform fatigue tests in order to generate experimental S-N curves for different Kt and stress ratios, allowing to identify an appropriate fatigue damage model.
  • Simulate the hole punching procedure in order to better understand the deformation and failure behaviour of bolted joints. This procedure causes modifications to the initial local material state in the surrounding areas of the punched holes and changes the overall mechanical behaviour of the bolted connections in fatigue.
  • Simulate and describe the fatigue behaviour of plates with holes using different approaches.
  • Assessment and selection of the best concept.