Researchers at the University of Surrey (UK), with colleagues from the University of California, Irvine and Johns Hopkins University, have developed a new material that is as stiff as metal but flexible enough to withstand strong vibrations (damping).

The researchers believe their new material could usher in a new wave of trains, cars, and aircrafts, allowing customers to experience little to no vibration during their travels. An open-access paper on their work is published in Scientific Reports.

The team achieved this near impossible combination in a material by using 3D woven technical textile composite sheets, with selected un-bonded fibers—allowing the inside of the material to move and absorb vibrations, while the surrounding material remains rigid.

… a selectively bonded 3DW lattice architecture was fabricated, tested and shown to exhibit noticeable combinations of damping and stiffness. Un-bonded lattice members were free to move within manufacturing gaps of 20~30% of their diameter. Computational results revealed a novel damping mechanism that relied on collisions between the free and brazed lattice members.

These impacts excited the natural frequencies of the surrounding media and disrupted the forcing signal. The developed architecture could be called a locally self-impacting metamaterial. The measured damping of a prototype sample was observed to increase with the forcing frequency, unlike in conventional bulk materials. Our technology may enable low pass filtering devices that allow for the passage of low-frequency vibrations but dampen the high-frequency signal.

In addition to damping and mechanical13 characteristics, 3DW lattice materials can exhibit tailored fluidic permeability, thermal transport and maintain their properties at high service temperature, which may suggest multi-functional capabilities for future studies.

—Salari-Sharif et al.

(a) 3D woven (3DW) lattice material is composed of Z- (green), warp (red) and fill (blue) wires; (b) Yellow color indicates the brazing locations (at the top and bottom). (c) Cross-section of 3D woven lattice with the stiff skeleton (the brazed portion on the top and bottom) and free lattice members in the core of the structure, (d) SEM image of the brazed top face, which confirmed metallurgical bonding of the metallic lattices. Salari-Sharif et al.

The idea of a composite the resolves the paradox of stiffness and damping was thought to be impossible—yet here we are. This is an exciting development that could send shock waves through the car, train and aerospace manufacturing industries. This is a material that could make the vehicles of the near future more comfortable than ever before.

—Dr Stefan Szyniszewski, lead author, Professor of Materials and Structures at the University of Surrey

Resources

• Ladan Salari-Sharif, Stephen M. Ryan, Manuel Pelacci, James K. Guest, Lorenzo Valdevit & Stefan Szyniszewski (2018) “Damping of selectively bonded 3D woven lattice materials” Scientific Reports Volume 8, Article number: 14572 doi: 10.1038/s41598-018-32625-6