Topology optimization-guided metal integration in fiber-reinforced polymer composites for enhanced resilience and reparability in structural connections

Abstract Inland waterway navigation is vital for efficient and cheap transport, made possible by the locks and dams that keep waterways navigable. Instead of traditional steel, using alternative materials such as glass fiber-reinforced polymer composites for locks and dams can significantly reduce corrosion and associated maintenance costs. However, composites are generally designed to fail in bearing around connections, a type of failure that is difficult to inspect and repair. In addition, designing composite connections for low bearing stress often requires large connection areas, which reduces overall efficiency. While adding steel inserts increases bearing strength and resulting joint efficiency, the repairability issue remains unresolved due to steel–composite interface failure. This study proposes a topology optimization-based design strategy for steel inserts that ensures failure initiation inside the steel insert and away from the composite, aiming to mitigate expensive composite repair and associated maintenance costs. An optimization formulation is developed to control the failure initiation region while satisfying the service load capacity and overall stiffness, which improves repairability of composite connections while retaining significant bearing strength and joint efficiency. We use the formulation to design optimized inserts that feature irregular patterns beyond human intuition. Several optimized inserts are fabricated and tested to successfully reproduce the desired failure location and validate that composite connections with optimized inserts attain better repairability than conventional connections. The improved repairability and resiliency in optimized composite connections from the proposed framework can potentially benefit various industrial applications, including waterway infrastructure, wind power generation, and aerospace components.