New Kagome Tube Structure Promises Enhanced Vibration Isolation

A newly developed 3D-printed structure known as the **kagome tube** may revolutionize how sensitive equipment is protected from damaging vibrations. This innovative design falls under the category of **topological mechanical metamaterials** and offers a practical solution for real-world applications, especially in civil and aerospace engineering.

Lead developer **James McInerney** of the **Wright-Patterson Air Force Base** in **Ohio, USA**, believes that this structure could serve as an effective shock absorber. The kagome tube features a lattice of beams specifically arranged to localize low-energy vibrational modes, known as **floppy modes**, to one side of the structure. McInerney explains, “This provides good properties for isolating vibrations because energy input into the system on the floppy side does not propagate to the other side.”

Innovative Design and Testing Procedures

The unique behavior of the kagome tube is attributed to the arrangement of the beams forming its lattice structure. Using a pattern originally proposed by **James Clerk Maxwell** in the 19th century, the beams are organized into repeating sub-units that create stable, two-dimensional structures known as **topological Maxwell lattices**. Previous iterations of these lattices could not support their own weight, necessitating rigid external mounts that hindered practical integration into devices.

In contrast, the new kagome tube is self-supporting, achieved by folding a flat Maxwell lattice into a cylindrical shape. This tube features a connected inner and outer layer—referred to as a **kagome bilayer**—and its radius can be engineered to achieve the desired topological behavior.

The research team, which documented their findings in **Physical Review Applied**, first conducted numerical tests by attaching a virtual version of the kagome tube to a mechanically sensitive sample alongside a source of low-energy vibrations. The results confirmed that the tube effectively diverted vibrations away from the sensitive sample.

To further analyze the tube’s geometry, the researchers developed a simple spring-and-mass model, treating it as a monolayer. This modeling indicated that the polarization of the kagome tube would mirror that of the monolayer. Additionally, they employed a finite-element method to calculate the frequency-dependent patterns of vibrations propagating across the structure, determining the effective stiffness of the lattice under different loads.

Potential Applications and Future Research

The primary focus of the research is to explore vibration isolation applications that could benefit from a **passive support structure**. This is particularly relevant in scenarios where the performance of existing passive mechanisms, such as **viscoelastomers**, is compromised by temperature limitations. McInerney elaborates, “Our tubes do not necessarily need to replace other vibration isolation mechanisms. Rather, they can enhance the capabilities of these by having the load-bearing structure assist with isolation.”

Looking ahead, the team recognizes that their most critical next step will be to investigate the implications of physically mounting the kagome tube onto its vibration isolation structures. McInerney notes that the numerical study conducted so far has utilized idealized mounting conditions, which may not accurately represent real-world scenarios. He emphasizes the need to account for potential impedance mismatches between the mounts and the tube in order to validate their work experimentally and provide realistic design scenarios.

As researchers continue to refine this innovative kagome tube design, its potential to enhance vibration isolation in sensitive equipment could lead to significant advancements in various engineering fields.