Fluid-filled cellular solids for controlled

• US 20040173422A1
• Filed: 03/03/2003
• Published: 09/09/2004
• Est. Priority Date: 03/03/2003
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Deshmukh, Suraj S., McKinley, Gareth H.
• Granted Patent: US 8,091,692 B2
• Time in Patent Office: Days
• US Class Current: 188/267.2
• CPC Class Codes: F16F 2224/043 electrorheological
• CPC Class Codes: F16F 2224/045 magnetorheological
• CPC Class Codes: F16F 9/003 Dampers characterised by having pressure absorbing means other than gas, e.g. sponge rubber
• CPC Class Codes: F16F 9/006 characterised by the nature of the damping medium, e.g. biodegradable variable viscosity damping adjustment F16F9/53

Abstract

An impact absorber using an energy-absorbing, fluid-impregnated material consisting of a porous interconnected network of solid material forming edges and faces of cells, preferably an open-cell reticulated or partially closed-cell foam, or formed from fibers or other cellular solids. The matrix is impregnated with a field responsive fluid such as a magneto- or electro-rheological fluid, or with a shear-rate responsive fluid such as a dilatant (shear-thickening) fluid. The material is placed under compression during impact, and may be housed within a cylinder and compressed by a piston. The stiffness of the composite material consisting of a matrix filled with a field responsive fluid can be controlled by varying the field intensity and spatial gradients of the applied field to vary the rheological properties of the fluid.

Claims

1. An impact absorber comprising composite material consisting of a cellular solid or a fibrous matrix, impregnated with a fluid, that stiffens under predetermined conditions, and means for compressing said composite material in response to an impact to dissipate the energy of said impact.

2. An energy absorber as set forth in claim 1 wherein the rheological properties of the said fluid change when subjected to a magnetic field.

3. An energy absorber as set forth in claim 2 including means for controlling the intensity and gradient of said magnetic field to vary the rheological properties of said fluid.

4. An energy absorber as set forth in claim 3 including a detector for sensing the magnitude of energy loading on the said cellular solid or fibrous matrix and means for controlling the intensity of said magnetic field to vary the rheological properties of said fluid in response to said magnitude.

5. An energy absorber as set forth in claim 1 wherein the rheological properties of said fluid change when subjected to an electric field.

6. An energy absorber as set forth in claim 5 including means for controlling the intensity and gradient of said electric field to vary the rheological properties of said fluid.

7. An energy absorber as set forth in claim 6 including a detector for sensing the rate of energy dissipation in said cellular solid or fibrous matrix and means for controlling the intensity of said electric field to vary the rheological properties of said fluid in response to said magnitude.

8. An energy absorber as set forth in claim 1 wherein the theological properties of said fluid vary when subjected to rapid deformation.

9. An impact absorber comprising composite material consisting of a cellular solid or a fibrous matrix impregnated with a magneto-rheological fluid having rheological properties that change when subjected to a magnetic field, said magneto-rheological fluid consisting of magnetizable particles suspended in non-magnetizable liquid carrier, means for compressing said composite material in response to an impact to dissipate the energy of said impact, and means for applying a controllable magnetic field to said composite material to vary the stiffness of said composite material.

10. An energy absorber as set forth in claim 9 including a detector for sensing the magnitude of energy applied to said cellular solid or fibrous matrix and means for controlling the intensity of said magnetic field to vary the rheological properties of said fluid in response to said magnitude.

11. An impact absorber comprising composite material consisting of a cellular solid or a fibrous matrix impregnated with a viscous fluid having rheological properties that vary under predetermined conditions, a housing for retaining said composite material in a confined space, means for compressing said composite material within said housing in response to an impact to dissipate the energy of said impact, and one or more restricted passageways for permitting a limited flow of said fluid to exit said housing when said material is compressed to further dissipate the energy of said impact.

12. An energy absorber as set forth in claim 11 wherein the rheological properties of said fluid change when subjected to a magnetic field.

13. An energy absorber as set forth in claim 12 including means for controlling the intensity and variation of said magnetic field to vary the rheological properties of said fluid.

14. An energy absorber as set forth in claim 13 including a detector for sensing the magnitude of energy applied to said cellular solid or fibrous matrix and means for controlling the intensity of said magnetic field to vary the rheological properties of said fluid in response to said magnitude.

15. An energy absorber as set forth in claim 11 wherein the rheological properties of said fluid change when subjected to an electric field.

16. An energy absorber as set forth in claim 15 including means for controlling the intensity and variation of said electric field to vary the rheological properties of said fluid.

17. An energy absorber as set forth in claim 16 including a detector for sensing the rate of deformation of said cellular solid or fibrous matrix and means for controlling the intensity of said electric field to vary the rheological properties of said fluid in response to said rate.

18. An energy absorber as set forth in claim 11 wherein rheological properties of said fluid change when subjected to rapid deformation.

19. An impact absorber comprising composite material consisting of a cellular solid or a fibrous matrix, impregnated with a viscous fluid, that stiffens under predetermined conditions, a cylinder for retaining said composite material in a compression chamber, and a piston mounted for axial movement within said cylinder for compressing said composite material within said housing in response to an impact to dissipate the energy of said impact.

20. An energy absorber as set forth in claim 19 wherein the rheological properties of said fluid change when subjected to a magnetic field.

21. An energy absorber as set forth in claim 20 including means for controlling the intensity and variation of said magnetic field to vary the rheological properties of said fluid.

22. An energy absorber as set forth in claim 21 including a detector for sensing the rate of deformation of said cellular solid or fibrous matrix and means for controlling the intensity of said magnetic field to vary the rheological properties of said fluid in response to said magnitude.

23. An energy absorber as set forth in claim 19 wherein said fluid is a shear-thickening fluid that increases in viscosity when subjected to rapid deformation.

24. An impact absorber as set forth in claim 19 further comprising one or more restricted passageways for permitting a limited flow of said fluid to exit said compression chamber when said composite material is compressed to further dissipate the energy of said impact.

25. An energy absorber as set forth in claim 24 wherein the rheological properties of said fluid change when subjected to a magnetic field.

26. An energy absorber as set forth in claim 25 including means for controlling the intensity of said magnetic field to vary the rheological properties of said fluid.

27. An energy absorber as set forth in claim 26 including a detector for sensing the magnitude of energy applied to said cellular solid or fibrous matrix and means for controlling the intensity of said magnetic field to vary the rheological properties of said fluid in response to said magnitude.

28. An energy absorber as set forth in claim 24 wherein said fluid is a shear-thickening fluid whose rheological properties change when subjected to rapid deformation.