Honeycomb shear testing method

• US 6,178,825 B1
• Filed: 06/28/1999
• Issued: 01/30/2001
• Est. Priority Date: 06/28/1999
• Status: Expired due to Fees

• Current Assignee: Aerospace Corporation
• Original Assignee: Aerospace Corporation
• Inventors: Welle, Richard P., Valenzuela, Pierre R., Chang, Dick J.
• Primary Examiner(s): NOORI, MAX H
• Application Number:
  US09/340,515
• Time in Patent Office: 582 Days
• Field of Search: 738/41, 738/18, 738/26, 738/46, 738/56
• US Class Current: 73/846
• CPC Class Codes: G01M 5/005 by means of external apparatus, e.g. test benches or portable test systems
• CPC Class Codes: G01N 2203/0096 Fibre-matrix interaction in composites
• CPC Class Codes: G01N 3/24 by applying steady shearing forces G01N3/26, G01N3/28 take precedence

Abstract

A shear test fixture and method determines the shear strength of a honeycomb having elongated cells extending between two ends filled with a filler material with a load applied to one end relative to the other end introducing shear stress without introducing compression or tension stress for improved shear strength testing.

Claims

1. A method of inducing stresses in a structure of cells positioned at a first end and at a second end of the structure, the method comprising the steps of,

disposing a filler material into the cells at the first end and into the cells at the second end of the structure,

rigidly clamping the first end of the structure,

rigidly clamping the second end of the structure for transferring a load force upon the structure, and

applying load induced displacement to the second end relative to the first end, the load inducing stresses in the structure.

2. The method of claim 1 wherein the load is a rotational load inducing shear and normal stresses in the structure.

3. The method of claim 1 wherein the load is a compression load inducing compressive stresses in the structure.

4. The method of claim 1 wherein the load is a pulling load inducing tension stresses in the structure.

5. The method of claim 1 further comprising the step of,

determining the mechanical properties of the structure under the load.

6. The method of claim 1 wherein the load is a shear load, the method further comprising the step of,

determining the shear properties of the structure under the shear load.

7. The method of claim 1, wherein the disposing step comprises the steps of,

disposing the filler material into the first end of the cells,

creating a partial vacuum within the cells at the second end, and

vacuum filling the second end of the structure with the filler material.

8. A method of testing for shear properties of a structure of cells positioned at a first end and at a second end of the structure, the method comprising the steps of,

disposing a filler material into the cells at the first end and into the cells at the second end of the structure,

rigidly clamping the first end of the structure,

rigidly clamping the second end of the structure for transferring a load force upon the structure,

applying load induced displacement to the second end relative to the first end, the load inducing stresses in the structure, and

determining the shear properties of the structure upon deformation the structure when under the load.

9. The method of claim 8 wherein the deformation of th e structure is elastic deformation.

10. The method of claim 8 wherein the deformation of the structure is inelastic deformation.

11. The method of claim 8 wherein the shear properties comprises shear failure strength.

12. The method of claim 8 wherein the shear properties comprises shear yield strength.

13. The method of claim 8, wherein,

the structure is a honeycomb structure, and

the cells are elongated hexagonal cells extending from the first end to the second end.

14. The method of claim 8 wherein the filler material is a polymer epoxy material with low viscosity, the method further comprising the step of curing the polymer epoxy material until rigid in the first end and the second end.

15. The method of claim 8 wherein the load is applied at a predetermined rate distance per minute.

16. The method of claim 8, wherein the disposing step comprises the steps of,

disposing the filler material into cells at the first end,

creating a partial vacuum within the cells at the second end, and

vacuum filling the cells at the second end with the filler material.

17. A method of testing for shear properties of a honeycomb structure of elongated hexagonal cells extending between a first end and a second end of the honeycomb structure, the method comprising the steps of,

disposing a filler material into the elongated hex cells at the first end,

creating a partial vacuum within the elongated hexagonal cells,

vacuum filling the elongated hexagonal cells at the second end with the filler material,

rigidly clamping the first end of the honeycomb structure,

rigidly clamping the second end of the honeycomb structure for transferring a load force upon the honeycomb structure,

applying load induced displacement to the second end relative to the first end, the load inducing stresses in the entire honeycomb, and

determining the shear properties of the honeycomb structure upon deformation of the honeycomb structure when the load is applied.

18. The method of claim 17 wherein the filler material is a polymer epoxy material with low viscosity, the method further comprising the step of curing the polymer epoxy material until rigid.