Multi-scale 3D Pentamode Metamaterial with Biconical Rods
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Solution Overview
Problem
Conventional three-dimensional pentamode structures have a limited adjustable range and are prone to manufacturing errors, particularly when trying to achieve specific bulk and shear moduli, which hampers their application in acoustic control and stealth technologies.
Innovation Solution
A multi-scale three-dimensional pentamode metamaterial with a body-centered cubic (BCC) structure, featuring node structures and rods with biconical through holes, allows for adjustable equivalent density and moduli through varying size parameters and fill rates of lattice structures, enabling more precise control over acoustic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the diameters of the thin ends of the biconical structure are reduced to achieve extreme parameter adjustments, then the bulk modulus can be optimized, but the forming error increases significantly and manufacturing precision deteriorates
Solution Approach 1:
The patent transitions from a two-dimensional honeycomb structure to a three-dimensional biconical diamond structure, adding a new dimensional degree of freedom. This 3D configuration allows independent adjustment of bulk and shear moduli through two controllable parameters (diameters of thick and thin ends), enabling extreme parameter optimization without the manufacturing precision penalties associated with 2D structures
Solution Approach 2:
The patent systematically varies the diameters of the thick ends and thin ends of the biconical structure to achieve different bulk and shear moduli. By controlling these geometric parameters within feasible manufacturing ranges, the design achieves extreme modulus values while maintaining acceptable forming accuracy, avoiding the need to reduce thin end diameters to impractically small dimensions
2Ease of manufacture
If the conventional biconical three-dimensional pentamode structure is used with limited adjustable parameters, then the structure is simple to manufacture, but the adjustable range of bulk and shear moduli is narrow
Solution Approach 1:
The patent employs two independent geometric parameters (diameters of thick ends and thin ends of the biconical structure) to control the bulk and shear moduli. This parameter-based design approach expands the adjustable range of elastic properties while maintaining structural simplicity and manufacturability, achieving a balance between ease of fabrication and design flexibility
3Strength
If the diameters of the thin ends are made excessively small to achieve certain modulus ratios, then the bulk modulus to shear modulus ratio increases, but the forming error becomes large and reliability decreases
Solution Approach 1:
By adopting a three-dimensional biconical diamond structure instead of a two-dimensional honeycomb, the patent gains an additional degree of freedom in design. This 3D configuration allows the bulk modulus to be optimized through the thick end diameter while the thin end diameter can be maintained at manufacturable dimensions, achieving high modulus ratios without the reliability penalties of excessively small features
Data Source
AI summary
The disclosure belongs to a technical field related to metamaterials and discloses a multi-scale three-dimensional pentamode metamaterial and an additive manufacturing method thereof. The multi-scale three-dimensional pentamode metamaterial has a body centered cubic (BCC) structure and includes a plurality of rods and a plurality of node structures. Two ends of each of the rods are connected to the node structures. Each of the rods has a cylindrical shape and is provided with a biconical through hole. From one end of the rod towards the other end of the rod, a diameter of the biconical through hole gradually decreases and then gradually increases. A chamber is formed inside each of the node structures, the biconical through hole communicates with the chamber, and the chamber is filled with a lattice structure.