Miniature reproduction of raking tests on marine structure: Similarity technique and experiment

Abstract

Substantial progress has been made in the last decades to computationally model the structural response of marine structures subjected to collision and grounding accidents. The finite element method stands out as the most reliable and robust technique within other tools for this purpose. However, there are still some complex physical aspects arduous to be modeled numerically. This work presents an experimental technique to reproduce the mechanical response and collapse mode of marine structures subjected to collision and grounding events by using miniature models built by additive manufacturing. This experimental technique relies on structural scaling and thickness distortion formulations. A raking test on a large-scale ship bottom was replicated in a 1:30 reduced scale to validate this technique. The miniature ship bottom structure was additively manufactured from stainless steel 316L considering all structural details. Flat dog-bone samples with different thicknesses were also built in the same way for mechanical characterization of the material via tensile tests and microscopy analysis of material fractures. Tensile tests showed a good consistency in stress-strain curves with a small, but noteworthy, influence of plate thickness and a large dispersion in rupture elongations. The fractured sections revealed various void formations around non-sintered metal powder. In spite of that, the structural response obtained from miniature test showed a good correspondence with the large-scale reference test when both are brought to the same dimensional scale.