Ship frame and grillage structural experiments

This paper discusses an experimental ship structural research program that is well underway at Memorial University. The series of structural experiments is exploring the extreme plastic behaviour of full scale ship frames under intense local loads. The program began with tests on single frames with support from Transport Canada and with a view to validating of the frame limit state equations that were developed for the recently developed Unified Requirements for Polar Ships. The program was then expanded to include small grillage tests, this with the aid of support from the US Coast Guard. The program was further expanded to include large grillage tests as part of a Ship Structures Committee project (SR1442) (managed by TC and DRDC). As a sequence of related experiments, we are able to see the influence of increasingly realistic boundary conditions on the plastic structural behaviour of a frame. The paper describes the experimental test arrangements, the data collection strategy and presents some of the results. Load, strains and large scale distortions are the main items being measured. Extensive ANSYS finite element analyses of frames/grillages have been conducted, which extend the range of the investigation. The work is still underway and results are only partial. Nevertheless, several new insights have been found. Proper consideration of plastic behaviour can help produce ship frames with both an enhanced linear range and large stable plastic reserve.NRC publication: Ye