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Strain based Keeler-Goodwin diagrams are widely used in forming processes to predict onset of local necking. Plastic instability is determined once the forming limit strain is exceeded. Use of these diagrams requires proportional strain paths, which is not necessarily the case in sheet metal forming operations. In many forming processes, the strain path changes during deformation. This may change the forming limit curve significantly. In the paper, a stress based forming limit criterion is adopted to deal with strain path non-linearities. Comparisons with earlier published work on forming limits are made through analytical considerations. Furthermore, the criterion is implemented into the finite element code LS-DYNA and verified numerically against results from large scale bulge tests.

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This paper describes the SIRIUS (Safe Installation with Ropes In Ultradeep Sea) JIP full scale testing program conducted to determine the bend fatigue performance of large diameter fibre ropes with HMPE fibres (Dyneema®) on small diameter sheaves, together with a summary of the results and the impact the results have on installation operations. The test rig has previously been used for testing of Ø109 mm steel wire ropes and these results will be used as benchmark for the fibre ropes tested at similar Safety Factors. Steel wire rope together with active heave compensation has been used for subsea deployment applications for many years. However, with the requirement to install heavy subsea hardware in increasingly deeper water, there is a need to use large diameter fibre rope as part of the deployment system.

It is clear that the offshore industry is striving to develop fields in deeper and deeper water and that subsea production is a key element in this development. This then leads to the question of what is the most efficient method of installing subsea production equipment in very deep water. This paper will address the issues associated with using conventional lifting technology based on steel wire rope for deep water applications. The new deep water construction ships being brought into operation have conventional lifting equipment based on steel wire rope. The requirement to be able to handle loads in excess of 300 t in great water depths leads to the need for large diameter multi-strand ropes with low spin characteristics. The long term behaviour of these ropes particularly in applications which require the use of heave compensator is uncertain due to the lack of any suitable test data. This paper will describe a full scale testing program to determine the fatigue performance of large diameter steel wire rope, including the design and building of a new testing machine, together with a summary of the results and the impact the results have on installation operations.