Programmable Metamaterial Lattice for Thermally Tunable Rigidity
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Solution Overview
Problem
Lattice structures typically maintain fixed properties throughout their lifetime, failing to adapt to changing requirements, and existing adaptive structures exhibit long actuation times, lack reversibility, or increased complexity, making them unsuitable for responsive applications.
Innovation Solution
A programmable metamaterial comprising a lattice structure with interconnected struts made from active and passive materials, where the active material has a higher modulus dependence on stimuli than the passive material, allowing for softening or stiffening upon exposure to a stimulus, enabling controlled macroscopic property changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If shape memory polymers are introduced to achieve thermally tunable elastic moduli and Poisson's ratios, then adaptability is improved, but actuation time increases and reversibility is lost
Solution Approach 1:
The patent changes the material parameter by using a passive polymer matrix combined with active particles that have distinct thermal response characteristics. The active particles undergo volume change or shape transformation at specific temperatures, while the passive matrix maintains structural integrity, enabling rapid and reversible adaptation without the time delays associated with shape memory polymers.
Solution Approach 2:
The patent employs a composite material system consisting of a passive polymer matrix and active particles (such as shape memory alloy particles or thermally responsive particles). This composite structure allows the passive matrix to provide structural stability while the active particles contribute thermal responsiveness, achieving both rapid actuation and reversibility through the synergistic interaction of different material phases.
2Adaptability or versatility
If hollow tubes filled with granular particles or magnetorheological fluid suspensions are used to achieve adaptive behavior, then adaptability is improved, but structural complexity increases and monolithic fabrication becomes difficult
Solution Approach 1:
The patent merges the passive structural matrix and active functional particles into a single integrated metamaterial system. The active particles are dispersed within the passive polymer matrix, creating a unified structure where the passive framework provides mechanical stability and the active particles provide adaptive functionality, eliminating the need for separate hollow tube structures or fluid-filled chambers.
Solution Approach 2:
The patent applies local quality by distributing active particles selectively within the passive matrix at specific locations to achieve desired adaptive properties. The concentration and distribution of active particles can be controlled to provide localized adaptability in specific regions of the metamaterial while maintaining overall structural simplicity and enabling monolithic fabrication.
3Adaptability or versatility
If existing adaptive structures are used, then adaptability is improved, but reversibility is lost
Solution Approach 1:
The patent utilizes phase transitions of the active particles (such as martensitic transformation in shape memory alloy particles or glass transition in thermally responsive particles) to achieve reversible adaptive behavior. These phase transitions are thermally driven and can be repeatedly cycled between austenite and martensite phases or between glassy and rubbery states, enabling the metamaterial to reversibly switch between different mechanical properties multiple times without degradation.
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 metamaterial can be monolithically fabricated by 3D printing and exhibits vastly different mechanical properties in response to stimuli, such as temperature, without altering behavior at ambient conditions, enabling adaptive applications like morphing structures and reconfigurable robots.
Implementation Method 1
the active material has a modulus with a higher stimulus dependence than that of the passive material. The active material is disposed at predetermined regions of the lattice structure to enable softening or stiffening of the predetermined regions upon exposure to a stimulus
Data Source
AI summary
A method of controlling macroscopic properties of a metamaterial includes 3D printing a lattice structure comprising interconnected struts, where each strut comprises one or more printed filaments. Each printed filament comprises an active material or a passive material, and the active material has a modulus with a higher stimulus dependence than that of the passive material. The printed filaments comprising the active material are disposed at predetermined regions of the lattice structure. After 3D printing, the lattice structure is exposed to a stimulus, and the predetermined regions comprising the active material soften or stiffen. Thus, the macroscopic properties of the lattice structure may be controlled.