Invention of new vitrified metal springs with record resilience, shaping and applications as high-end sensors and switches. – Nouveaux ressorts vitrifiés
This project concerns a new type of spring with high resilience and high precision mechanical strength above 3 GPa up to 5 GPa. The behavior and configuration of these springs are based on the response of an arc (semi-circle) of vitrified metal constrained between two plates under a force perpendicular to its diameter. The completely different behavior of such an arc of a film or sheet of vitrified metal compared to that of a sheet of crystalline metal is at the origin of the new type of springs and its configurations. The nature of the vitrified metal sheet in a semicircle or a half-wavelength allows elastic deformation under pressure by a reversible ripple mechanism that is unavailable to the arcs made of crystalline materials. This reversible deformation traces a predictable shape modification path of the arc in accordance with the increase of the applied force which allows the design of new types of load and movement sensors that may function as mechanical or electromechanical switches.
Tests completed to date have used vitrified metal sheets of 20 µm thickness corresponding to vertical and horizontal dimensions of the order of 4 and 40 mm respectively for the entire device. The upper limit of the reversible deformation e and the half-wavelengths of the ripples (undulations) that form with increasing load are dimensionally bound by the ratio e ~ d / D where d is the thickness of the vitrified metal sheet and D the diameter of curvature. The overall dimensions of the device are also proportional to the thickness d. Therefore, the use of vitrified film thickness of about 1 or 5 microns will reduce the vertical and horizontal dimensions of the device to 200 µm and 2 mm or 1 mm and 10 mm respectively. This miniaturization will allow applications in the strategic field of MEMS (micro-electromechanical systems) and advanced robotics and micro-robotics.
In a different approach, vitrified foils may also be curved to desired shapes and annealed to fix the selected shapes for the fabrication of so-called “wave-springs” of superior resilience. These may be used as corrugated sheet or ring-shaped springs.
This discovery is the result of an accumulation of expertise funded by ANR, the European Commission and a private company as well as a PhD granted at the INPG in 2011. The knowledge-base comes from an ANR project entitled "Ductile Metallic Glasses 2006-2009" (BLANC-035) and a European type RTN "Ductile BMG Composites 2004-2008", both designed and coordinated by the same SIMaP laboratory team. The know-how resulted in the development of new vitrified alloy compositions for high end springs of mechanical watches, leading to the filing of a European and a US patent for the protection of the best nouvel compositions in 2011. INPG patent rights to those compositions were then sold to in 2012.
Our project has the overall specific objectives to design and manufacture new types of wave-springs made of corrugated vitrified metal foils and to demonstrate their applications in areas such as sensors and switches of millimeter dimensions.
Monsieur Alain YAVARI (Science et Ingénierie des MAtériaux et Procédés- CNRS UMR 5266 – INPG – UJF) – firstname.lastname@example.org
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
SIMaP Science et Ingénierie des MAtériaux et Procédés- CNRS UMR 5266 – INPG – UJF
GUV Guichet Unique Valorisation - Institut Polytechnique de Grenoble
Help of the ANR 213,720 euros
Beginning and duration of the scientific project: March 2013 - 24 Months