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US 8,282,746 B2Granted
Superelastic alloy structural geometry for ultrahigh mechanical damping
AssigneeMassachusetts Institute of Technology
InventorsChristopher A. Schuh, Jose M. San Juan, Ying Chen
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Abstract
A mechanical structure is provided with a crystalline superelastic alloy that is characterized by an average grain size and that is characterized by a martensitic phase transformation resulting from a mechanical stress input greater than a characteristic first critical stress. A configuration of the superelastic alloy is provided with a geometric structural feature of the alloy that has an extent that is no greater than about 200 micrometers and that is no larger than the average grain size of the alloy. This geometric feature is configured to accept a mechanical stress input.
Claims45
A mechanical structure comprising:
- a crystalline superelastic alloy characterized by an average grain size and characterized by a martensitic phase transformation resulting from a mechanical stress input greater than a characteristic first critical stress;
- and
- a configuration of the superelastic alloy providing a geometric structural feature of the alloy having an extent that is no greater than about 200 micrometers and that is no larger than the average grain size of the alloy, the geometric feature being characterized by a merit index for mechanical damping, (1/π)E1/2(ΔW/Wmax), that is at least about 0.5, where E is Young's modulus for the alloy feature, ΔW is dissipated energy per unit volume of the alloy feature for one cycle of phase transformation with the input mechanical stress, and Wmax is maximum stored mechanical energy per unit volume of the alloy feature for one cycle of phase transformation with the input mechanical stress.
A mechanical structure comprising:
- a crystalline superelastic alloy characterized by an average grain size and characterized by a martensitic phase transformation resulting from a mechanical stress input greater than a characteristic first critical stress;
- and
- a configuration of the superelastic alloy providing a geometric structural feature of the alloy having an extent that is no greater than about 200 micrometers and that is no larger than the average grain size of the alloy, the geometric feature being configured to damp mechanical vibrations from the mechanical stress input wherein mechanical vibration damping is characterized for the geometric structural feature by a merit index for mechanical damping, (1/π)E1/2(ΔW/Wmax), that is at least about 0.5, where E is Young's modulus for the alloy feature, ΔW is dissipated energy per unit volume of the alloy feature for one cycle of phase transformation with the input mechanical stress, and Wmax is maximum stored mechanical energy per unit volume of the alloy feature for one cycle of phase transformation with the input mechanical stress.
A mechanical damping system comprising:
- a mechanical support through which mechanical stress is input;
- a mechanical system;
- and
- a mechanical connection between the mechanical system and the mechanical support provided by at least one crystalline superelastic alloy structure having an average grain size and being characterized by a martensitic phase transformation resulting from a mechanical stress input greater than a characteristic first critical stress, a configuration of the superelastic alloy structure providing a geometric structural feature of the alloy including a structural feature having an extent that is no greater than about 200 micrometers and that is no larger than the average grain size, the geometric structural feature being characterized by a merit index for mechanical damping, (1/π)E1/2(ΔW/Wmax), that is at least about 0.5, where E is Young's modulus for the alloy, ΔW is dissipated energy per unit volume of the alloy structure for one cycle of phase transformation with the input mechanical stress, and Wmax is maximum stored mechanical energy per unit volume of the alloy structure for one cycle of phase transformation with the input mechanical stress to accept the input mechanical stress.
1 more element
A mechanical damping system comprising:
- a mechanical housing having an input end through which mechanical stress is input;
- a mechanical support;
- and
- a mechanical connection between the housing and the support provided by at least one crystalline superelastic alloy structure having an average grain size and being characterized by a martensitic phase transformation resulting from a mechanical stress input greater than a characteristic first critical stress, a configuration of the superelastic alloy structure providing a geometric structural feature of the alloy including a structural feature having an extent that is no greater than about 200 micrometers and that is no larger than the average grain size of the alloy, the geometric structural feature being characterized by a merit index for mechanical damping, (1/π)E1/2(ΔW/Wmax), that is at least about 0.5, where E is Young's modulus for the alloy structure, ΔW is dissipated energy per unit volume of the alloy structure for one cycle of phase transformation with the input mechanical stress, and Wmax is maximum stored mechanical energy per unit volume of the alloy structure for one cycle of phase transformation with the input mechanical stress to accept the input mechanical stress.
1 more element
Dependencies are inferred from the claim text.