Method and device for testing a material sample in a standard test for inplane fracture toughness evaluation

• US 10,690,575 B2
• Filed: 07/03/2019
• Issued: 06/23/2020
• Est. Priority Date: 06/15/2017
• Status: Active Grant

• Current Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Original Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Inventors: Traidia, Abderrazak, Chatzidouros, Elias, Jouiad, Mustapha
• Primary Examiner(s): Dunlap, Jonathan M
• Application Number:
  US16/502,568
• Publication Number:
  US 20190323932A1
• Time in Patent Office: 356 Days
• Field of Search: 73849, 73799, 73856
• CPC Class Codes: G01N 1/04 in the solid state, e.g. by cutting
• CPC Class Codes: G01N 2001/2886 Laser cutting, e.g. tissue catapult
• CPC Class Codes: G01N 2203/0064 Initiation of crack
• CPC Class Codes: G01N 2203/0066 Propagation of crack
• CPC Class Codes: G01N 2203/0067 Fracture or rupture
• CPC Class Codes: G01N 2203/027 Specimens with holes or notches
• CPC Class Codes: G01N 2203/0298 Manufacturing or preparing specimens
• CPC Class Codes: G01N 3/02 Details
• CPC Class Codes: G01N 3/04 Chucks
• CPC Class Codes: G01N 3/20 by applying steady bending forces G01N3/26, G01N3/28 take precedence

Abstract

A method of testing a material sample of a type used in a wall of a structure in a standard test for in-plane fracture toughness evaluation. The method comprises obtaining a sample having a lateral length no larger than a thickness of the wall of the structure, shaping the sample to have (a) a bottom surface, (b) a profiled top surface having a central notch, (c) a first coupling feature on a first side of the central notch, and (d) a second coupling feature on a second side of the central notch, assembling a test specimen which increases the width of the sample beyond the lateral width by coupling a first lateral extension to the first coupling feature and a second lateral extension to the second coupling feature, and applying a standard fracture toughness test to the so-assembled test specimen and sample to evaluate the fracture toughness of the sample.

Claims

1. A method of testing a material in a standard test for in-plane fracture toughness evaluation, the material sample of a type used in a wall of a structure, the method comprising:

obtaining a sample of the wall of the structure;

shaping the sample into a notched component, the notched component including a flat bottom surface having a thickness dimension equal to a thickness of the wall of the structure, and a profiled top surface, the profiled top surface having a central notch oriented perpendicular to a plane of the bottom surface to define a crack, a first socket on a first side of the central notch, and a second socket on a second side of the central notch;

assembling a test specimen which increases an effective thickness of the sample beyond the thickness of the bottom surface of the notched component by coupling a first lateral extension to the first socket and a second lateral extension to the second socket of the notched component;

applying a standard fracture toughness test to the so-assembled test specimen in order to evaluate the fracture toughness of the material in an in-plane direction by creating a bending moment that opens the crack defined by the central notch; and

machining the notched component such that the central notch is oriented to open in a S-L direction in a standard fracture toughness test,

wherein the crack in the central notch includes a first section of rectangular cross section having a first width and a distinct second section having a second width that is smaller than the first width, and wherein the bending moment opens the crack by increasing the first and second widths.

2. The method of claim 1, further comprising forming the first and second lateral extensions such that a sum of the lengths of the first and second lateral extensions and the thickness of the notched component is as great or greater than 4.5 times the width of the notched component as measured from the bottom surface to a tip of the profiled surface.

3. The method of claim 1, wherein the first and second sockets are symmetrical about the central notch.

4. The method of claim 1, wherein the first and second sockets are asymmetrical about the central notch.

5. The method of claim 1, wherein the standard fracture toughness test applies force to the bottom surface of the notched component.

6. The method of claim 1, wherein the first and second sockets are elbow-shaped notches.

7. The method of claim 1, wherein the structure as a thickness ranging from about 5 mm to about 70 mm.

8. The method of claim 1, wherein the first and second lateral extensions have a length (L) that is set according to the following inequality

2L+T≥

4.5W

in which T is the thickness of the sample and W is the width of the notched component.

9. An apparatus for testing a material used in a wall of a structure for fracture toughness, the apparatus comprising:

a notched component made from a sample of the material of the structure shaped to have (a) a bottom surface having a width equal to a thickness of the wall of the structure, (b) a profiled top surface, the profiled top surface having a central notch that defines a crack, (c) a first socket on a first side of the central notch, and (d) a second socket feature on a second side of the central notch;

a first lateral extension coupled to the first socket of the notched component; and

a second lateral extension coupled to the second socket of the notched component,

wherein the first and second lateral extensions extend an effective width of the notched component to provide an assembled test specimen of sufficient length to be used in a standard fracture toughness test, and

wherein the central notch of the notched component is oriented to open in a S-L direction in a standard fracture toughness test,

wherein the crack in the central notch includes a first section of rectangular cross section having a first width and a distinct second section of having a second width that is smaller than the first width, and wherein a bending moment created by the standard fracture toughness test tends to open the crack by increasing the first and second widths.

10. The apparatus of claim 9, wherein the first and second lateral extensions are formed such that a sum of the lengths of the first and second lateral extensions and the thickness of the notched component is as great or greater than 4.5 times the width of the notched component as measured from the bottom surface to a tip of the profiled surface.

11. The apparatus of claim 9, wherein the structure has a thickness ranging from about 5 mm to about 70 mm.

12. The apparatus of claim 11, wherein the pipe structure is made of X65 steel.