Reliability-based topology-topography optimization for ship bulkhead structures considering multi-failure modes

Bulkhead structure is an important support form widely used in ship components, which is not only affected by loads and random factors but also has various failure forms. In this work, a novel reliability-based topology-topography optimization (RBTTO) method is presented to address the bulkhead lightweight and reliability design problems with multi-failure modes. Within the framework of reliability-based design optimization (RBDO), an innovative topology-topography optimization (TTO) method based on material penalization and node activation (MPNA) model and a new reliability assessment strategy considering joint influences of multi-failure modes are proposed. In the TTO approach, the topography deformation nodes are activated by the MPNA matrices according to the element density of SIMP (Solid Isotropic Microstructures with Penalization) to realize the integrated design of topology and topography optimization. The multi-failure reliability assessment strategy is developed, which establishes the most probable point based uncertainty analysis through the probabilistic criterion of system safety and the expert elicitation theory. This RBTTO method is applied to the RBDO of a typical ship bulkhead. The findings show that the bulkhead obtained by RBTTO satisfies the reliability considering uncertain multi-failure modes and exhibits superior overall lightweight and mechanical properties than those of other methods. •Reliability-based optimization for ship bulkheads with multi-failure modes.•Topology-topography optimization using material penalization and node activation model.•Multi-failure mode assessment strategy for reliability evaluations.•Optimized bulkhead satisfies reliability requirements and achieves better lightweight and mechanical properties.