Methods and devices for electrochemically determining metal fatigue status

• US 6,026,691 A
• Filed: 06/30/1995
• Issued: 02/22/2000
• Est. Priority Date: 06/30/1995
• Status: Expired due to Term

• Current Assignee: EFS International SA, University of Pennsylvania
• Original Assignee: University of Pennsylvania
• Inventors: Li, Yuanfeng, Laird, Campbell
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US08/501,879
• Time in Patent Office: 1,698 Days
• Field of Search: 73/806, 73/808, 73/810, 73/813, 73/799, 324/693, 324/701, 324/71.1, 204/400, 204/401, 204/404, 204/406, 204/407, 204/224 R, 204/242, 204/271, 204/277, 204/267
• US Class Current: 73/808
• CPC Class Codes: G01N 17/02 Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement
• CPC Class Codes: G01N 2203/0073 Fatigue

Abstract

Devices and methods for determining the fatigue status of a metallic specimen are provided. The methods utilize the devices, which are an array of a number of cells or modules. Each cell in the array has an electrode, and an electrolyte in contact with a surface of the specimen. The cells of the array can determine a relative fatigue status of a large surface area of the specimen of interest.

Claims

1. A device for determining a fatigue status of a metallic specimen which comprises,

(a) an array containing a plurality of cells being electrically connected to said specimen, each cell having a reference and a counter electrode;

(b) a potentiostat for each cell, being connected to said electrodes of each cell, for controlling a voltage applied across each cell, and carrying a sensing current from each cell;

(c) an amplifier for each potentiostat, being connected to each said potentiostat, for amplifying the sensing current;

(d) a multiplexer, being connected to said amplifiers, for sequentially sensing the amplified sensing current from each of the plurality of cells;

(e) an analog-to-digital converter, being connected to the multiplexer, for converting the amplified sensing current from each of the plurality of cells from an analog to a digital format;

(f) a microcontroller, being connected to said converter, for recording and storing the digital form of the currents;

wherein said currents being provided by the plurality of cells determine a relative fatigue status of the specimen;

wherein the microcontroller produces digital control signals for controlling the potentiostats;

(g) a digital-to-analog converter, being connected to said microcontroller, for converting the digital control signals from a digital to an analog format; and

(h) a second multiplexer, being connected to the digital-to-analog converter, for applying the analog form of the control signals to each of the potentiostats.

2. The device of claim 1 which further comprises a resistor for grounding each potentiostat.

3. The device of claim 1 wherein the second multiplexer is connected to a sample/hold circuit for each potentiostat.

4. The device of claim 3 wherein circuit is in communication with one potentiostat, thereby allowing for varying the voltage controlled by that potentiostat.

5. A device for determining a fatigue status of a metallic specimen which comprises,

(a) an array containing a plurality of cells being electrically connected to said specimen, each cell having a reference and a counter electrode;

(b) a potentiostat, being connected to said electrodes, for controlling a voltage applied across each cell and carrying a sensing current from each cell;

(c) an amplifier, being connected to said potentiostat, for amplifying the current;

(d) a multiplexer, being connected to said amplifier, for sequentially sensing the plurality of cells and for obtaining a readout of the current;

(e) an analog-to-digital converter being connected to said multiplexer, for converting the current from an analog to a digital format; and

(f) a microcontroller, being connected to said converter, for recording and storing the current readout;

said readout being provided by the plurality of cells being capable of determining a relative fatigue status of the specimen, and

wherein said device further comprises a means for controlling the operation of said device, and said digital-to-analog converter is connected to said microcontroller, and wherein said converter is further connected to a second multiplexer.

6. The device of claim 5 wherein the second multiplexer is connected to a sample/hold box.

7. The device of claim 6 wherein the sample/hold box is in communication with said potentiostat, thereby allowing for varying the voltage controlled by said potentiostat.