Composite/Hybrid Structural Engineering

Advanced Composite-to-Metal Joining

Beltran Inc’s state-of-the-art composite-to-metal (hybrid) joining technology uniquely leverages the use of The Welding Institute’s (Cambridge, UK) SurfiScuplt® metal surface protrusion and a modified Vacuum-Assisted Resin Transfer Molding (VARTM) process enabling simultaneous formation of the composite structure and consolidation of that with the metal counterpart.

The metal protruded surface “pins” composite to metal adding a mechanical component to the adhesive bonding increasing its structural performance to that comparable with strong bonded-bolted joints. The benefits include weight and life-cycle cost saving that allows effective implementation of the hybrid ship hull concept associated with an increase of speed, payload and/or non-refueled range, superior signature control, improved propulsion, bettered inclination stability and corrosion prevention.

Figure 1 illustrates the joining concept while Figure 2 generalizes a hybrid hull architecture regarding both major classes of naval ships, surface vessels and submarines, for which a robust, structurally efficient and reliable joining of heterogeneous (composite-metal) structures is a critical component.

Figure 1: Composite-to-metal joining concept

Figure 2: Conceivable applications of metal-composite hybrid joints

Hybrid Hull Design

While beneficial for several key performance parameters, the application of structural composites for use with primarily metal ship hulls is challenged by specific complications of the use of two- and multi-material hull design and construction. These complexities affect the areas of structural interruptions, such as intersections of the hull structural members, which are the main contributors to premature material cracking during ship construction and/or operation. Besides, the structural complication is associated with disproportional increase of the hull construction cost which is of significant concern to the viability of government-funded shipbuilding programs. It is anticipated that design and construction of a hybrid hull will be especially intricate as the traditional design pertinent to a mono-material hull is being applied. Consequently innovative design solutions relevant to material-transition structures are needed to provide structurally and cost-efficient implementation of the hybrid hull concept. Beltran has developed expertise enabling the implementation of customized guidelines in support of hybrid hull design and the manufacturing processes necessary to commercialize them.

Serviceability Characterization of Composite/Hybrid Structures

The existing guidelines for structural design of naval craft are primarily devised for metal hulls and are not fully adequate to address the peculiarities of a hybrid (composite-metal) hull. Beltran Inc. possesses an experimentally-verified analytical technique that bridges this design challenge and provides accurate characterization of serviceability of composite/hybrid structures undergoing changing force-environmental operational conditions. Beltran’s approach is applicable to both hybrid hull design and conventional procedures using design strength reconciliation. In the result, a reliable, structurally/weight efficient service performance of a composite/hybrid hull would be assured.