What is it about?
We present a simple experimental method to detect topologically protected soft and stiff spots in mechanical metamaterials. Drawing on an electrostatic analogy, we locally perturb the system, identify “mechanical molecules”, and measure their effective “polarisation”. Sudden changes in this polarisation field signal the presence of topological features in the structure. Importantly, this is done by simply tracking displacements and elongations in the system, without requiring information about any underlying model.
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Why is it important?
The notion of topological phases is rather abstract, and the characterization of the spectral topology has hitherto relied on pre-existing idealized theoretical models. This has limited experiments primarily to validating these models’ predictions through analog simulations. Our work prioritizes experimental investigation, demonstrating a generic, model-independent method for identifying topological states in mechanical systems. This approach broadens the reach of topological phases beyond designer materials and allows their direct experimental investigation. We expect this insight into topological mechanics to make it accessible to a broader range of physicists and engineers and to open guidelines to construct genuine functional materials beyond laboratory demonstrators.
Perspectives
Experimental investigation of topological systems has been restricted to those aligning with mathematical models for which we already have a theoretical description. We remove this constraint in mechanics by establishing a link between physical observables and topological properties, allowing for the investigation and design of new topological materials without imposing any artificially crafted symmetry. Our model-independent methodology not only advances the field of mechanical metamaterials but also paves the way for exploring topological properties in other domains such as photonics and acoustics, without the constraints of predefined theoretical models.
Marcelo Guzman
University of Pennsylvania
Read the Original
This page is a summary of: Model-free characterization of topological edge and corner states in mechanical networks, Proceedings of the National Academy of Sciences, January 2024, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2305287121.
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