Open Lattice Composite Truss via Maypole Braiding
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Solution Overview
Problem
Existing methods for manufacturing composite truss structures face challenges such as stress concentrations at bolt holes, difficulty in resin infusion, and inefficiencies in creating open lattice structures without metallic joining techniques, which hinder the achievement of lightweight and strong composite materials.
Innovation Solution
The use of large prepreg yarns with a thermoplastic jacket, braided or wrapped, on a conventional maypole braiding machine to create an open structure composite member, where resin infusion and curing produce strong joints and a lightweight truss structure without mechanical attachment hardware, utilizing a simple mandrel and adjustable braiding speeds for variable geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bolting is used to join composite truss elements, then structural assembly is achieved, but stress concentrations at bolt holes occur which may lead to failure
Solution Approach 1:
The patent merges the truss elements and joints into a single integrated composite structure. Fibers continue uninterrupted through the joints, eliminating separate bolted connections. This combining of elements removes the interface between fasteners and composite material, thereby eliminating stress concentration points while maintaining structural integrity.
Solution Approach 2:
The patent uses continuous fiber reinforcement that spans across what would traditionally be joint locations. The fibers are embedded in the matrix material and extend through the entire truss structure, creating a homogeneous composite material system that eliminates the need for mechanical fasteners and their associated stress concentration problems.
2Strength
If conventional metal truss structures are used, then high strength and stiffness are achieved, but weight is excessive
Solution Approach 1:
The patent changes the material parameters from isotropic metals to anisotropic composite materials. By orienting fibers along the primary load paths and using high-strength-to-weight ratio composite materials, the structure achieves comparable or superior strength while significantly reducing weight. The fiber orientation and material composition are optimized for specific loading conditions.
Solution Approach 2:
The patent segments the continuous fiber reinforcement into discrete bundles or tows that are strategically placed along different truss members and joints. Each fiber bundle is oriented to carry specific loads, allowing optimization of material distribution and weight reduction while maintaining overall structural strength.
3Weight of moving object
If open lattice structure is created without metallic joining techniques, then weight is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent replaces mechanical joining systems (bolts, welds, rivets) with a chemical/biological system - the curing of resin matrix that bonds fibers together. The manufacturing process uses automated fiber placement or braiding machines that lay down preimpregnated fiber tapes, which are then cured in place. This substitution eliminates complex mechanical assembly operations while achieving strong joints.
Solution Approach 2:
The patent applies preliminary action by preimpregnating the fiber bundles with resin before placement in the final structure. The fibers arrive pre-coated with the matrix material at controlled resin-to-fiber ratios, eliminating the need for post-placement resin application and ensuring consistent quality. The structure is then cured in its final configuration, locking in the open lattice geometry.
4Strength
If resin infusion is performed in traditional composite truss manufacturing, then joints are strengthened, but resin infiltration becomes difficult due to open spaces
Solution Approach 1:
The patent inverts the traditional sequence by placing fibers first in the desired open lattice configuration, then infusing resin into the void spaces. Rather than trying to force resin through densely packed fibers, the open structure naturally facilitates resin flow and infiltration. The resin is introduced into the open spaces between fiber bundles, ensuring complete joint penetration and bonding.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of composite trusses with enhanced strength-to-weight ratio, scalable manufacturing, and easier mandrel removal, avoiding surface irregularities and achieving significant weight savings over metal or solid composite structures.
Implementation Method 1
heating to a temperature sufficient to melt the thermoplastic jacket and/or cause the resin to exude from the yarns
Implementation Method 2
heating to a temperature sufficient to melt the thermoplastic jacket and/or cause the resin to exude from the yarns
Data Source
AI summary
Preforms for open structured (lattice) composite tubular members manufactured from large (i.e. high filament count) prepreg yarns on a conventional maypole braiding machine, and subsequently cured to produce fiber reinforced composites of high strength and light weight.