Electrochemical fatigue sensor systems and methods

• US 20070074976A1
• Filed: 09/30/2005
• Published: 04/05/2007
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: EFS International SA
• Original Assignee: Material Technologies, Inc.
• Inventors: Moshier, Monty, Berks, William
• Granted Patent: US 7,572,360 B2
• Time in Patent Office: Days
• US Class Current: 205/790.500
• CPC Class Codes: G01N 17/02 Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement
• CPC Class Codes: G01N 2203/0066 Propagation of crack
• CPC Class Codes: G01N 2203/0073 Fatigue
• CPC Class Codes: G01N 2203/0629 using thin films, paintings
• CPC Class Codes: G01N 27/403 Cells and electrode assemblies
• CPC Class Codes: G01N 3/32 by applying repeated or pulsating forces

Abstract

A method for determining a fatigue status of a growing crack in a substrate. An electrochemical sensor device is provided and includes an electrode formed from a stainless steel mesh. The electrochemical device has a bottom surface that contacts the substrate. The bottom surface is coated with an adhesive layer, and a release paper is attached to the adhesive layer. The release paper is separated from the adhesive layer, thereby exposing the adhesive layer. The electrochemical sensor device is secured to the substrate by bringing the adhesive layer in contact with the substrate and thereby forming an electrolyte cavity bounded in part by the substrate. The adhesive seals the bottom surface of the device to the substrate in order to prevent leakage of electrolyte from the cavity. The cavity is filled with the electrolyte. When the substrate is subjected to cyclic loading, the fatigue status of the growing crack in the substrate is determined in accordance with a measured current between the reference electrode and the substrate.

Claims

1. A method for determining a fatigue status of a growing crack in a substrate, comprising:

(a) providing an electrochemical sensor device that includes an electrode formed from a stainless steel mesh, wherein the electrochemical device has a bottom surface that contacts the substrate, the bottom surface is coated with an adhesive layer, and a release paper is attached to the adhesive layer;

(b) separating the release paper from the adhesive layer, thereby exposing the adhesive layer;

(c) securing the electrochemical sensor device to the substrate by bringing the adhesive layer in contact with the substrate and thereby forming an electrolyte cavity bounded in part by the substrate, wherein the adhesive seals the bottom surface of the device to the substrate in order to prevent leakage of electrolyte from the cavity;

(d) filling the cavity with the electrolyte; and

(e) determining, when the substrate is subjected to cyclic loading, the fatigue status of the growing crack in the substrate in accordance with a measured current between the reference electrode and the substrate.

2. An electrochemical sensor device for determining a fatigue status of a growing crack in a substrate, comprising:

(a) a reference electrode formed from a stainless steel mesh material that is substantially impermeable to an electrolyte, wherein the reference electrode has a bottom side that faces the substrate and a top side that faces away from the substrate, and wherein at least one opening is provided in the mesh material, said at least one opening being sufficient in size to permit electrolyte to flow through the reference electrode;

(b) a first electrolyte cavity formed between the substrate and the bottom side of the reference electrode;

(c) a second electrolyte cavity formed between the top side of the reference electrode and a cover of the device;

(d) an electrolyte inlet port formed in a wall of the first electrolyte cavity;

(e) a bleeder output port formed in a wall of the second electrolyte cavity; and

(f) a sensor that measures a current between the reference electrode and the substrate when the substrate is subjected to cyclic loading.

3. A method for determining a fatigue status of a growing crack at a suspected fatigue location on a substrate, comprising:

(a) providing a first electrochemical sensor device that includes a first reference electrode;

(b) providing a second electrochemical sensor device that includes a second reference electrode;

(c) positioning the first electrochemical sensor device over the suspected fatigue location on the substrate, and measuring a first current signal between the first reference electrode and the substrate when the substrate is subjected to cyclic loading;

(d) positioning the second electrochemical sensor device at a location on the substrate where fatigue cracking is not probable, and measuring a second current signal between the second reference electrode and the substrate when the substrate is subjected to cyclic loading; and

(e) assessing the fatigue status of the growing crack at the suspected fatigue location by comparing information from the first and second current signals.