Simulation on progressive collapse behaviour of whole ship model under extreme waves using idealized structural unit method

• The applicability of total simulation system including load calculation and structural collapse analysis has been confirmed.
• The ultimate hull girder strength in hogging is reduced by about 20% under the alternate heavy loading condition.
• The post-ultimate strength behaviour can be simulated if dynamic collapse analysis is performed.
• The computation time of ISUM is about 1/70 of MARC. The high efficiency and sufficient accuracy of ISUM are demonstrated.

To ensure the safety of navigating ship, working loads and structural load-carrying capacity are two important aspects. In the present paper, a total simulation system combing load calculation and structural collapse analysis is applied to simulate progressive collapse behaviour of a single-hull Kamsarmax type bulk carrier. A three dimensional singularity distribution method is adopted to calculate pressure distribution with time history. A mixed structural model, collapse part simulated by ISUM elements and remaining part by elastic FEM elements with relative coarse mesh, is proposed for collapse analysis. Progressive collapse behaviour obtained by ISUM is good agreement with that by nonlinear software package, MARC. However, the calculation time of ISUM analysis is about 1/70 of MARC analysis. The applicability to structure system, high accuracy and sufficient efficiency of ISUM had been demonstrated.