A numerical simulation study of boundary-condition effects on the damage of ship grillages due to ice impacts

• Main Authors: Gagnon, Robert, Quinton, Bruce, Mackay, John
• Format: Article in Journal/Newspaper
• Language: English
• Published: IAHR 2022
• Subjects: sea ice; ships and navigation in ice; Sea ice
• Online Access: https://nrc-publications.canada.ca/eng/view/object/?id=296fe8ef-6e5e-48ec-a85c-98b647d096de; https://nrc-publications.canada.ca/fra/voir/objet/?id=296fe8ef-6e5e-48ec-a85c-98b647d096de

In the study of ship-grillage damage due to collisions with ice masses, an important aspect is the set of boundary conditions around the impacted hull segment where the damage occurs. This is true for both physical experiments in the lab and numerical simulations. Here we use numerical simulations to investigate the influence of various boundary conditions on the plastic-damage response of two grillage segments of the same size, from the decommissioned Royal Canadian Navy destroyer Ex-HMCS IROQUOIS, subjected to collisions with a given ice mass. One of the grillage segments facilitates ice impacts between two stiffeners, and the other segment facilitates ice impacts at a stiffener. The simulation components comprise a large conceptual apparatus presently under development that will eventually be used in an ice tank to perform large-scale physical impact tests on actual grillage segments. The apparatus, known as HITT (Heavy Impact Test Theater), will consist of a large impactor (to attach grillages to) and an actual ice feature (with augmented mass) that the impactor collides with. The present simulation study will help define suitable boundary conditions for the attachment of the grillage segments to the impactor. Here the results are quantitatively discussed in terms of the boundary-conditions effect on the impact loads and the residual plastic indentation of the impacted grillages, and qualitatively in terms of the effect on the characteristics of associated stiffener deformations. One particular set of boundary conditions was identified as exhibiting the desired realistic ice-impact grillage behaviors and being the easiest to implement in the HITT apparatus. Peer reviewed: Yes NRC publication: Yes