What are mechanical metamaterials?
Metamaterials are engineered materials with unique properties that differ from those of conventional materials. These properties are primarily determined by the arrangement of their constituent elements, often referred to as the unit cell. By carefully controlling the geometry of the unit cell, designers can tailor the material's behavior to meet specific needs.
The choice of materials is crucial in designing components and systems. Traditional materials are often selected based on their mechanical characteristics. However, the limitations of these materials can constrain design options and performance.
Unlike homogeneous materials, which have fixed properties, periodic metamaterials offer greater flexibility. Their properties depend not only on the constituent materials but also on the overall structure's geometry. This means that designers can achieve a wide range of material properties by altering the structure without changing the underlying materials. This flexibility allows metamaterials to meet multiple design requirements simultaneously.
Metamaterials have found applications in various fields, including medicine, photonics, thermal management, and acoustic-vibrational control. While their potential in reducing noise in buildings and vehicles at specific frequencies has been explored, there is still significant room for further research and development in this area.
Auxetic materials: An example of cellular materials
Auxetic materials are a class of materials characterized by a negative Poisson's ratio. This means that when subjected to a uniaxial tensile load, they expand laterally instead of contracting, resulting in an overall increase in dimensions. Conversely, under compression, they contract in all directions.
This unique property endows auxetic materials with exceptional characteristics, such as high shear strength, superior indentation resistance, and good fracture toughness. These special properties have led to a wide range of applications in fields including medicine, transportation, aerospace, energy absorption, and vibration and acoustic damping.
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