# US 9,752,639 B2 · Fluids having a controlled stress response characteristic > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,639 B2 - Document ID: US9752639B2 - Status: Granted - Kind: B2 - Application number: 14/752,495 - Filed: 2015-06-26 - Published: 2016-12-29 - Granted: 2017-09-05 - Earliest claimed: 2015-06-26 - Assignees: Palo Alto Research Center Incorporated - Applicants: Palo Alto Research Center Incorporated - Inventors: Victor Alfred Beck - Web page: https://patentgrep.com/patent/US9752639B2 ## CPC - F16F 9/12: Devices with one or more rotary vanes turning in the fluid any throttling effect being immaterial, {i.e. damping by viscous shear effect only (F16F9/53 takes precedence; pivoting supports for apparatus or articles placed on stands or trestles F16M11/06)} - F16F 9/006: {characterised by the nature of the damping medium, e.g. biodegradable (variable viscosity damping adjustment F16F9/53)} - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION ## Abstract A shear thickening fluid having a controlled stress response, in which various stress response characteristics, including, an onset stress, a boundary stress and a fractures stress, can be controlled. The stress response characteristics controlled by the controlled properties of the shear thickening fluid, including the viscosity of a fluid medium, the mechanical properties of the suspended particles and the mechanical properties of the fluid boundary. ## Claims ### Claim 1 A shear thickening fluid having a controlled stress response, the controlled stress response having a controllable onset stress at which an onset viscosity of the shear thickening fluid begins to increase in response to an applied shear stress and a controllable boundary stress at which a boundary viscosity of the shear thickening fluid reaches a maximum viscosity in response to the applied shear stress, the shear thickening fluid, comprising: a fluid medium comprising at least one fluid and a plurality of particles; the fluid medium having a fluid medium characteristic; the plurality of particles suspended in the fluid medium, the plurality of particles having a particles characteristic; a boundary enclosing the fluid suspended in the fluid medium, the boundary having a boundary characteristic; wherein at least one of the fluid medium characteristic, the particles characteristic and the boundary characteristic are selected based on at least one of a preselected magnitude of the controllable onset stress and a preselected magnitude of the controllable boundary stress of the shear thickening fluid; and wherein at least one of the plurality of particles has the particles characteristic comprising a hollow interior surrounded by a shell having a thickness. ### Claim 2 (depends on 1) The shear thickening fluid of claim 1, wherein at least one of the fluid medium characteristic is a viscosity of the fluid medium. ### Claim 3 (depends on 1) The shear thickening fluid of claim 1, wherein at least one of the particles characteristic is a diameter of the particles. ### Claim 4 (depends on 3) The shear thickening fluid of claim 3, wherein the diameter of the particles is substantially the same for each of the plurality of particles. ### Claim 5 (depends on 3) The shear thickening fluid of claim 3, wherein the diameter of the particles is variable for each of the plurality of particles. ### Claim 6 (depends on 1) The shear thickening fluid of claim 1, wherein at least one of the particles characteristic is a particle fraction of the shear thickening fluid. ### Claim 7 (depends on 1) The shear thickening fluid of claim 1, wherein at least one of the particles characteristic is an elastic modulus of the particles. ### Claim 8 (depends on 1) The shear thickening fluid of claim 1, wherein the particles characteristic includes the thickness of the shell. ### Claim 9 (depends on 1) The shear thickening fluid of claim 1, wherein the shell of each of the plurality of particles includes silica glass formed using an acid etch process. ### Claim 10 (depends on 1) The shear thickening fluid of claim 1, wherein multiple openings are disposed across the shell of each of the particles, the openings structured to have fluid communication between the fluid medium and the hollow interior of each of the particles. ### Claim 11 (depends on 1) The shear thickening fluid of claim 1, wherein each of the plurality of particles is composed of a material having mechanical properties that includes a fracture stress and an elastic modulus, and wherein at least one of the particles characteristic includes the material. ### Claim 12 (depends on 1) The shear thickening fluid of claim 1, wherein each of the plurality of particles includes silica glass. ### Claim 13 (depends on 1) The shear thickening fluid of claim 1, wherein at least one of the boundaries is a boundary fluid enclosing the shear thickening fluid. ### Claim 14 (depends on 1) The shear thickening fluid of claim 1, wherein at least one of the boundaries is a housing enclosing the shear thickening fluid and the housing is composed of a material having low elastic modulus. ### Claim 15 (depends on 14) The shear thickening fluid of claim 14, wherein the housing includes at least a sprung surface, the sprung surface varying a volume of the housing in response to the applied shear stress. ### Claim 16 A rotary dashpot, comprising: at least one housing including side walls and enclosing: a shear thickening fluid having a controlled stress response, the controlled stress response having a controllable onset stress at which an onset viscosity of the shear thickening fluid begins to increase in response an applied shear stress and a controllable boundary stress at which a boundary viscosity of the shear thickening fluid reaches a maximum viscosity in response to the applied shear stress; a rotor structured to at least partially rotate within the shear thickening fluid; and a stator disposed opposite the rotor and forming at least one of the boundaries enclosing the shear thickening fluid; wherein, when the rotor rotates within the shear thickening fluid, the rotation of the rotor in the shear thickening fluid applies the shear stress to the shear thickening fluid, the shear thickening fluid including: a fluid medium comprising at least one fluid and a plurality of particles; the fluid medium having a fluid medium characteristic; the plurality of particles suspended in the fluid medium, the plurality of particles having a particles characteristic; at least one of the housing, the rotor and the stator having a boundary characteristic; wherein at least one of the fluid medium characteristic, the particles characteristic and the boundary characteristic are selected based on at least one of a preselected magnitude of the controllable onset stress and a preselected magnitude of the controllable boundary stress; and wherein at least one of the plurality of particles has a hollow interior surrounded by a shell having a thickness. ### Claim 17 (depends on 16) The rotary dashpot of claim 16, wherein at least one of the boundary characteristic is the elastic modulus of a material of one or more of the housing, the rotor and the stator in contact with the shear thickening fluid. ### Claim 18 (depends on 16) The rotary dashpot of claim 16, wherein at least one of the boundary characteristic is at least a sprung surface in one or more of the housing, the rotor and the stator in contact with the shear thickening fluid, the sprung surface displacing in response to the applied shear stress. ### Claim 19 (depends on 16) The rotary dashpot of claim 16, wherein the particles characteristics includes the thickness of the shell. ### Claim 20 (depends on 16) The rotary dashpot of claim 16, wherein each of the plurality of particles are composed of a particles material having mechanical properties including a fracture stress and an elastic modulus and wherein at least one of the particles characteristic includes the particles material. ### Claim 21 (depends on 20) The rotary dashpot of claim 20, wherein the shear thickening fluid transitions to a shear thinning fluid in response to the applied shear stress exceeding the fracture stress of the particles.