Investigating disruption propagation and resilience of supply chain networks: interplay of tiers and connections

The resilience of supply chain networks (SCNs) is critical for economic stability. This study examines SCN resilience by analysing their response to disruptions in complex, multi-tier structures. Using a network generator algorithm, we simulated disruption impacts and recovery across SCNs ranging from two to seven tiers. Resilience was assessed through average functionality and recovery duration, leading to eight significant observations. The study addresses literature gaps by exploring tier-specific effects, realistic disruption dynamics, facility and connection disruptions, and the role of intra-/inter-tier connections. It evaluates mitigation strategies such as redundancy, supplier diversification, and government support. Case studies on a biofuel SCN and a municipal solid waste system are included in the supplementary material. Results indicate that disruptions persist longer in higher tiers, with Tier 7 experiencing up to 26% disruption duration, compared to 3% and 7% in the first and second tiers. Increasing redundancy reduces recovery time by up to 57% in seven-tier SCNs while expanding the supplier base from one to two regions cuts recovery time by up to 50%. These insights offer strategies for enhancing SCN resilience and guiding future research.