Apparatus for an anvil system that provides enhanced self-resistive specimen heating when used in a dynamic thermo-mechanical material testing system

1. Apparatus for an anvil assembly ( 200 ) for use in a material testing system ( 100 ) which controllably deforms a specimen, the apparatus comprising:

an anvil base ( 241 );

an anvil top ( 240 ); and

a foil interface ( 242 ) situated between the anvil base and the anvil top, wherein the foil interface comprises at least one composite layer ( 320 A , 320 B , 320 C ) having first and second differing components ( 313 , 315 ; 323 , 325 ; 333 , 335 ) situated in different corresponding first and second regions in the layer and having a predefined geometric orientation with respect to each other, the first component being a conductive material which provides a predefined resistance to current flow there through so as to generate a desired amount of self-resistive heat in the anvil assembly for a given amount of heating current passing through the first region, and the second component being an electrically insulating material that has sufficient physical strength so as not to be appreciably deformed during each deformation of the specimen.

2. The apparatus in claim 1 wherein each of the first and second regions has the same thickness, but a diameter of the first region differs from that of the second region such that the component in each of the regions exhibits desired physical, electrical and thermal properties.

3. The apparatus in claim 2 wherein the foil interface further comprises multiple, separate ones of the composite layer so as to define a plurality of composite layers arranged in an anvil stack ( 300 ).

4. The apparatus in claim 3 wherein each of the composite layers has a predetermined thickness such that resistance provided by all the composite layers, through their corresponding first components, is sufficient to produce the desired amount of said heat in the anvil assembly for the given amount of heating current.

5. The apparatus in claim 4 wherein a conductive disk ( 317 , 327 ) is situated between successive ones of the composite layers in the stack.

6. The apparatus in claim 5 wherein the conductive disk comprises a tantalum disk.

7. The apparatus in claim 5 wherein the first (or second) component is mica and the second (or first) component is graphite.

8. The apparatus in claim 5 further comprising an insulating holder situated circumferentially around all sides of the anvil stack so as to substantially prevent the heat and the heating current from flowing out the sides of the anvil stack.

9. The apparatus in claim 8 wherein the anvil stack is substantially conical in shape.

10. The apparatus in claim 1 wherein the orientation is substantially concentric, with the first region forming a solid centrally-located disk in the composite layer and having a predefined thickness and diameter, the second region having a ring shape with the same thickness as the first region, wherein the second region is located peripherally around the first region so as to yield a solid disk for the composite layer.

11. The apparatus in claim 10 wherein the foil interface further comprises multiple, separate ones of the composite layer so as to define a plurality of composite layers arranged in an anvil stack ( 300 ).

12. The apparatus in claim 11 wherein each of the composite layers has a predetermined thickness such that resistance provided by all the composite layers, through their corresponding first components, is sufficient to produce the desired amount of said heat in the anvil assembly for the given amount of heating current.

13. The apparatus in claim 12 wherein a conductive disk is situated between successive ones of the composite layers in the stack.

14. The apparatus in claim 13 wherein the conductive disk comprises a tantalum disk.

15. The apparatus in claim 13 wherein the first (or second) component is mica and the second (or first) component is graphite.

16. The apparatus in claim 13 further comprising an insulating holder situated circumferentially around all sides of the anvil stack so as to substantially prevent the heat and the heating current from flowing out the sides of the anvil stack.

17. The apparatus in claim 16 wherein the anvil stack is substantially conical in shape.

18. The apparatus in claim 1 wherein the first region contains at least one predefined space for the second region, wherein the space has a circular, triangular or rectilinear shape.

19. The apparatus in claim 18 wherein the foil interface further comprises multiple, separate ones of the composite layer so as to define a plurality of composite layers arranged in an anvil stack.

20. The apparatus in claim 19 wherein each of the composite layers has a predetermined thickness such that resistance provided by all the composite layers, through their corresponding first components, is sufficient to produce the desired amount of said heat in the anvil assembly for the given amount of heating current.

21. The apparatus in claim 20 wherein a conductive disk is situated between successive ones of the composite layers in the stack.

22. The apparatus in claim 21 wherein the conductive disk comprises a tantalum disk.

23. The apparatus in claim 21 wherein the first (or second) component is mica and the second (or first) component is graphite.

24. The apparatus in claim 21 further comprising an insulating holder situated circumferentially around all sides of the anvil stack so as to substantially prevent the heat and the heating current from flowing out the sides of the anvil stack.

25. The apparatus in claim 24 wherein the anvil stack is substantially conical in shape.