Output member for a direct impact Hopkinson pressure bar

Abstract

An output member for a Direct Impact Hopkinson pressure bar includes an elongate tube portion and a disc-shaped cap portion. The tube portion has a first end and an opposite second end, while the cap portion includes a first face and an opposite second face. A circular stub protrudes from a center of the first face, and a circular cavity is formed in the second face. Each of the stub and the cavity is concentric with the cap portion, with a diameter of the cavity being greater than a diameter of the stub. The second face of the cap portion is positioned in intimate contact with the first end of the tube portion, with the cap portion being concentric with the tube portion.

Claims

1. An output member for a Direct Impact Hopkinson pressure bar, comprising: an elongate tube portion comprising a first end and an opposite second end; and a disc-shaped cap portion comprising a first face and an opposite second face, wherein a circular stub protrudes from a center of the first face, a circular cavity is formed in the second face, each of the stub and the cavity being concentric with the cap portion, a diameter of the cavity being greater than a diameter of the stub, and the second face of the cap portion being positioned in intimate contact with the first end of the tube portion, with the cap portion being concentric with the tube portion.

2. The output member as claimed in claim 1, wherein the diameter of the stub is between 0.8 and 0.95 of the diameter of the cavity.

3. A Direct Impact Hopkinson pressure bar comprising an output member as claimed in claim 2.

4. The output member as claimed in claim 1, wherein the diameter of the stub is approximately 0.9 of the diameter of the cavity.

5. A Direct Impact Hopkinson pressure bar comprising an output member as claimed in claim 4.

6. The output member as claimed in claim 1, the cap portion further comprising an axial length being defined between the first face and the second face, wherein a depth of the circular cavity is between 6 mm and 12 mm less than the axial length.

7. A Direct Impact Hopkinson pressure bar comprising an output member as claimed in claim 6.

8. The output member as claimed in claim 1, wherein a distal surface of the circular stub is faced with a facing layer.

9. A Direct Impact Hopkinson pressure bar comprising an output member as claimed in claim 8.

10. The output member as claimed in claim 8, wherein the facing layer is formed from a material selected from the group comprising steels and titanium alloys.

11. A Direct Impact Hopkinson pressure bar comprising an output member as claimed in claim 10.

12. The output member as claimed in claim 1, wherein the cap portion is formed from a material selected from the group comprising aluminum alloys and magnesium alloys.

13. A Direct Impact Hopkinson pressure bar comprising an output member as claimed in claim 12.

14. The output member as claimed in claim 1, wherein the elongate tube portion comprises an internal cushion at the second end.

15. A Direct Impact Hopkinson pressure bar comprising an output member as claimed in claim 14.

16. A Direct Impact Hopkinson pressure bar comprising an output member as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There now follows a description of an embodiment of the disclosure, by way of non-limiting example, with reference being made to the accompanying drawings in which:

(2) FIG. 1 shows a schematic elevational view of a Direct Impact Hopkinson pressure bar according to the prior art;

(3) FIG. 2 shows a schematic partial sectional view of an output tube according to a first embodiment of the disclosure; and

(4) FIG. 3 shows a schematic, perspective view of the cap portion of the output member of FIG. 2.

(5) It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION

(6) Referring to FIGS. 2 and 3, an output member for a Direct Impact Hopkinson pressure bar according to a first embodiment of the disclosure is designated generally by the reference numeral 100.

(7) The output member 100 comprises an elongate tube portion 110 and a disc-shaped cap portion 120. The tube portion 110 has a first end 112 and an opposite second end 114.

(8) The cap portion 120 has a first face 122, an opposite second face 124, and an axial length 130. The axial length 130 extends between the first face 122 and the second face 124.

(9) A circular stub 140 protrudes from a center of the first face 122 of the cap portion 120. A circular cavity is formed in the second face 124 of the cap portion 120. Each of the circular stub 140 and the circular cavity 126 is concentric with the cap portion 120.

(10) A diameter 128 of the circular cavity 126 is greater than a diameter 142 of the circular stub 140. In the present arrangement, the diameter 142 of the circular stub 140 is 0.9 times the diameter 128 of the circular cavity 126. In other arrangements the ratio between the diameter 142 of the circular stub 140 and the diameter 128 of the circular cavity 126 may be between 0.8 and 0.95, with the proviso that the diameter 128 of the circular cavity 126 is always greater than the diameter 142 of the circular stub 140.

(11) The axial length 130 of the cap portion 120 is greater than the depth 132 of the circular cavity 126 by a distance of 10 mm.

(12) This geometry defines a shear zone 146 between the circular stub 140 and the cap portion 120. In other words, the shear zone is an annular ring of material extending axially from the first face of the cap portion to the distal face (i.e. the bottom) of the circular cavity, and extending radially from the outer diameter of the circular stub to the inner diameter of the circular cavity.

(13) The shear zone can be defined by a shear zone aspect ratio; this being the ratio of the axial length of the shear zone to the radial width of the shear zone.

(14) In the present embodiment, the shear zone has a radial width of 2.5 mm and an axial thickness of 7 mm. This provides a shear zone aspect ratio of 2.8.

(15) In the present arrangement, the cap portion 120 is formed from an aluminum alloy. In an alternative arrangement, the cap portion 120 may be formed from a magnesium alloy.

(16) The distal surface 144 of the circular stub 140 is provided with a facing layer 148. The facing layer 148 is formed from a high strength steel. In an alternative arrangement, the facing layer 148 may be formed from a titanium alloy.

(17) In use, the cap portion 120 is positioned at the first end 112 of the tube portion 110 to together form the output member 100. The cap portion 120 is concentric with the tube portion 110. The output member 100 is then installed in a Direct Impact Hopkinson pressure bar apparatus with the apparatus being used in the conventional manner.

(18) The foregoing description of various aspects of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to a person of skill in the art are included within the scope of the disclosure as defined by the accompanying claims.