Monolithic Lattice Truss Structures via Extrusion and EDM
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Solution Overview
Problem
Conventional methods for fabricating lattice truss sandwich structures often result in node bond failure due to poor joint design or inadequate bonding, leading to premature failure under shear or bending loads, and existing methods struggle to achieve high-quality structures with optimal core relative density and robustness.
Innovation Solution
A two-step manufacturing process involving extrusion and selective material removal using electro discharge machining to create monolithic lattice truss structures without the need for adhesives, brazing, or welding, ensuring a robust node-facesheet interface with identical metallurgical and microstructural properties across the truss units and facesheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional joining methods (adhesive bonding, brazing, welding) are used to attach lattice core to facesheets, then the structure can be assembled from separate components, but node bond failure occurs leading to premature failure under shear or bending loads
Solution Approach 1:
The patent merges the core and facesheet into a single monolithic structure through continuous material extrusion, eliminating the separate bonding interface that causes node failure. The lattice truss sandwich structure is fabricated as one integral piece, removing the weak adhesive or metallurgical bonds between core and facesheet.
Solution Approach 2:
The patent extracts and removes the bonding process entirely from the manufacturing sequence. By using monolithic extrusion, the structure is created without requiring adhesive bonding, brazing, or welding operations, thereby eliminating the source of node bond failure modes.
2Shape
If lattice truss structures are fabricated from high ductility alloys by folding perforated metal sheets, then the core can achieve desired topology, but the node area is reduced and bond strength is compromised
Solution Approach 1:
The patent changes the material state from folded thin sheets to continuously extruded monolithic material. This parameter change allows for larger node areas and more robust connections while maintaining the desired lattice topology, as the extruded material provides sufficient volume and strength at node regions.
Solution Approach 2:
The patent replaces the mechanical folding and bonding system with a monolithic extrusion system. Instead of folding perforated sheets and bonding them together, the entire lattice structure is extruded as one piece, substituting the multi-step mechanical assembly process with a continuous forming process that inherently creates stronger nodes.
3Reliability
If monolithic extrusion is used to fabricate lattice structures, then node bond failure is eliminated, but the manufacturing process complexity increases
Solution Approach 1:
The patent segments the manufacturing process into two distinct stages: extrusion of the monolithic lattice structure, followed by selective material removal to create the final sandwich configuration. This segmentation simplifies each individual step while achieving the complex monolithic structure, making the overall process more manageable and reliable.
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
The method produces sandwich structures with enhanced truss-facesheet interface strength, reducing the likelihood of node failure and achieving mechanical properties that align with micromechanical model predictions, while expanding the range of metals that can be fabricated into cellular structures with improved robustness and reduced corrosion risk.
Implementation Method 1
selective material removal using electro discharge machining
Data Source
AI summary
Methods and systems to manufacture lattice-based sandwich structures from monolithic material. Such methods and systems eliminate the bonding process which is conventionally used to join lattice based truss cores to facesheets to form sandwich structures. This bonded interface is a key mode of failure for sandwich structures which are subjected to shear or bending loads because the nodes transfer forces from the face sheets to the core members while the topology for a given core relative density dictates the load carrying capacity (assuming adequate node-bond strength exists). An aspect comprises a core and related structures that provide very low density, good crush resistance and high in-plane shear resistance. An aspect of the truss structures may include sandwich panel cores and lattice truss topology that may be designed to efficiently support panel bending loads while maintaining an open topology that facilitates multifunctional applications.