Architected material design for seismic isolation

Abstract

Seismic protection materials are derived from assemblages of unit cells, where each of the cells has a core, one or more shells disposed about the core, and rigid plates bounding the shells. The cores limit relative vertical movement between the plates, and the shell(s) limit relative lateral motion between the plates. Uncompressed cores are preferably substantially spherical or cylindrical, and can be solid or hollow. Unit cells can be aligned in same or different directions, both within a given layer of cells, and in different layers of cells. Assemblages can have any suitable overall shape and size, depending upon application, and for example can support objects ranging from table top equipment to large buildings and bridges.

What is claimed is: 
     
         1 . An apparatus for seismic isolation, comprising:
 a unit cell including (a) at least first and second plates disposed separately by a non-zero distance, and (b) at least a first shell attached to the first and second plates; and   a three-dimensional organized cellular material comprising multiple instances of the unit cell.   
     
     
         2 . The apparatus of  claim 1  wherein the first shell is generally tubular, with an at least partially curved perimeter extending between the first and second plates. 
     
     
         3 . The apparatus of  claim 2  wherein the perimeter has a curvature that varies between the first and second plates. 
     
     
         4 . The apparatus of  claim 1  wherein the unit cell further comprises a second shell disposed about the first shell. 
     
     
         5 . The apparatus of  claim 1  wherein the unit cell comprises at least a first cylindrical core disposed within the first shell. 
     
     
         6 . The apparatus of  claim 1  wherein the unit cell comprises at least a first spherical core disposed within the first shell. 
     
     
         7 . The apparatus of  claim 1  wherein the three-dimensional organized cellular material further comprises at least first and second layers, each of which includes the first plate. 
     
     
         8 . The apparatus of  claim 1  wherein the unit cell further comprises a second shell oriented in a different direction than the first shell. 
     
     
         9 . The apparatus of  claim 7  wherein the unit cells of the first layer have first cores oriented in a first direction, and the unit cells of the second layer have second cores oriented in a second direction different from the first direction. 
     
     
         10 . The apparatus of  claim 1  wherein the three-dimensional organized cellular material comprises at least one layer having first and second cores oriented in different directions. 
     
     
         11 . The apparatus of  claim 1  wherein the three-dimensional organized cellular material comprises a first and second arrays of the unit cell oriented in a different directions, respectively. 
     
     
         12 . The apparatus of  claim 1  wherein first and second instances of the unit cell each comprise a material selected from the group consisting of solid metallic materials, solid polymeric materials, solid ceramic materials, and solid composite materials. 
     
     
         13 . The apparatus of  claim 1  wherein first and second instances of the unit cells comprise different first and second materials selected from the group consisting of solid metallic materials, solid polymeric materials, solid ceramic materials, and solid composite materials. 
     
     
         14 . An apparatus for seismic isolation, comprising a three-dimensional organized cellular material having a plurality of unit cells with a shear strain deformation capacity between 0.2 and 2, a Shear modulus to Young's modulus ratio G/E between 0.01 and 0.1, and a damping ratio between 0.05 and 0.40. 
     
     
         15 . An apparatus for seismic isolation, comprising a three-dimensional organized cellular material having a plurality of unit cells with a shear strain deformation capacity between 0.2 and 2, a Shear modulus to Young's modulus ratio G<10 GPA and E=10 to 60 GPA between 0.01 and 0.1, and a damping ratio between 0.05 and 0.40. 
     
     
         16 . A method of providing seismic protection for a structure, comprising supporting the structure at least in part with a seismic isolation device as described in  claim 1 . 
     
     
         17 . The method of  claim 16  further comprising including in the structure an additional energy dissipation device. 
     
     
         18 . The apparatus of  claim 7  wherein the first and second layers are disposed as a double cone. 
     
     
         19 . The apparatus of  claim 1  wherein the three-dimensional organized cellular material has a height to width ratio between 0.05 and 0.5, inclusive. 
     
     
         20 . An apparatus for seismic isolation comprising:
 a three-dimensional organized cellular material; and   wherein the three-dimensional organized cellular material has a void to full volume ratio between 0.02 and 0.5, inclusive.