Improving operational resilience of naval vessels through the modelling of subsystem interdependency

Simulation, planning, and maintenance play critical roles in the demanding environment of naval operations. Despite recent technological advancements, the number of real-life incidents continues to persist. The root cause of many of those failures is a lack of understanding of the interoperability between seemingly small yet critical subsystems, as well as human error. In this thesis, a modelling technique and optimization tool is presented, combining human factors with a subsystem interdependence model via the Infrastructure Interdependencies Simulator (i2SIM). The goal of this work is to improve operational readiness through appropriate allocation of resources, considering the interdependence of vessel subsystems and the operational capabilities of the crew. The research proposes two i2SIM models, one that aims to be representative of the operational conditions of a vessel during its regular course of action. The operational model relates subsystem interactions that offer vessel operators insight into their system behaviours. The other model aims to incorporate human factors such as training and fatigue and their impact on recovery efforts post-faults. These models were constructed based on manufacturer data as well as failure modes, effects, and criticality analysis reports. Two case studies are presented that explore the operation and repair scheme of a combined diesel and gas naval vessel. This model evaluates the simulated real-time state of these subsystems, their importance for the vessel's mission readiness and their interdependencies that may impair the vessel's operational capabilities if one or more subsystems fail or underperform. These investigative methods entail scenario-based testing in i2SIM, where multiple "what-if" scenarios are simulated to mimic different operational states and emergency conditions to evaluate various resource allocation strategies. Through these simulations, the research explores possible interoperable systems. It also assesses repair distribution techniques. The findings of the case studies call for an integrated approach combining an understanding of cascading system failures as well as human factors’ impact. This thesis aims to be an effort in bridging the gap between theoretical modelling and practical application, offering a scalable, flexible framework for improving resilience in naval operations while addressing broader challenges in system-of-systems engineering.