Composite self-healing system

• US 9,180,632 B2
• Filed: 03/05/2014
• Issued: 11/10/2015
• Est. Priority Date: 04/13/2007
• Status: Active Grant

• Current Assignee: Cornerstone Research Group, Inc.
• Original Assignee: Cornerstone Research Group, Inc.
• Inventors: Hemmelgarn, Christopher Douglas, Margraf, Thomas Wood, Havens, David Ernest, Reed, John Lewis, Snyder, Logan Wayne, Dietsch, Benjamin Allen, Louderbough, Anthony
• Primary Examiner(s): Satanovsky, Alexander
• Application Number:
  US14/198,091
• Publication Number:
  US 20140186476A1
• Time in Patent Office: 615 Days
• US Class Current: 1/1
• CPC Class Codes: B29C 35/0272 using lost heating elements, i.e. heating means incorporated and remaining in the formed article for preforms with internal stresses B29C61/0625; joining using lost heating elements B29C65/34; making electrically conductive articles B29C70/882
• CPC Class Codes: B29C 73/18 the article material itself being self-sealing, e.g. by compression
• CPC Class Codes: B29C 73/22 the article containing elements including a sealing composition, e.g. powder being liberated when the article is damaged
• CPC Class Codes: B32B 43/00 Operations specially adapted for layered products and not otherwise provided for, e.g. repairing; Apparatus therefor

Abstract

An advanced reflexive structure system is disclosed. The reflexive system mimics the pain withdrawal reflex on which the human body relies. The reflexive system incorporates a continuous health and performance monitoring system via an embedded dielectric film, an adaptive composite structure based on shape memory composite material, and an intelligence system which will be interfaced with both the health/performance sensors and the adaptive structure. When activated shape memory polymer will recover its structural integrity via shape recovery and a reptation healing process. These features enable the use of SMP as an adaptive structure in the proposed reflexive system. The development of a reflexive system for structures will enable increased safety and security and demonstrate a better understanding of integrated performance systems. This reflexive technology could find immediate implementation on all current and future systems and future implementation on platforms such as the International Space Station, Lunar, and Martian habitats.

Claims

1. A self-healing system comprising:

at least one composite panel formed from a cured product of stacked plies, the stacked plies comprising;

a first ply of an adaptive structure comprising a shape memory polymer chosen from thermoset shape memory polymers and thermoplastic shape memory polymers;

a second ply comprising an array of heater sections formed from a matrix of discrete heating elements, wherein each discrete heating element is configured to heat a region corresponding to a single heater section; and

a third ply comprising a sensor grid array;

a damage detecting system that sends a waveform to the sensor grid array and receives a response from the sensor grid array to produce a data set;

a control system that analyzes the data set to determine at least one damage location of damage to the at least one composite panel, determines a target healing area based on the damage location, and selectively activates and deactivates individual heating elements of the matrix of discrete heating elements to cause localized heating in the target healing area that activates a combination of self-healing mechanisms in the adaptive structure, the combination of self-healing mechanisms comprising shape memory effect and reptation.

2. The self-healing system of claim 1, wherein the shape memory polymer is a thermoset shape memory polymer.

3. The self-healing system of claim 2, wherein the thermoset shape memory polymer is a styrene-based shape memory polymer.

4. The self-healing system of claim 2, wherein the thermoset shape memory polymer is an epoxy-based shape memory polymer.

5. The self-healing system of claim 1, wherein the adaptive structure is a composite of the shape memory polymer and a reinforcement embedded in the shape memory polymer, the reinforcement chosen from continuous fibers, fiber mats, chopped fibers, fiberglass, spandex, nanoparticles, carbon nanofibers, and carbon nanotubes.

6. The self-healing system of claim 5, wherein the shape-memory polymer is a thermoset styrene-based shape memory polymer and the reinforcement comprises carbon fibers.

7. The self-healing system of claim 1, wherein the second ply is between the first ply and the third ply.

8. The self-healing system of claim 1, wherein the third ply is between the first ply and the second ply.

9. The self-healing system of claim 1, wherein the control system comprises a printed circuit board, DC power supply, capacitors, a computer, programmable microprocessor, and cooling fan.

10. The self-healing system of claim 1, wherein the control system further comprises an interface between the control system and the individual discrete heating elements.

11. The self-healing system of claim 10, wherein the interface comprises a power source and switches that turn the power source on or off to vary a voltage drop across the individual discrete heating elements.

12. The self-healing system of claim 11, wherein the switches are mechanical relays.

13. The self-healing system of claim 1, further comprising a monitor coupled to the control system, the monitor adapted to display status information to a user about a healing process being controlled by the control system.

14. The self-healing system of claim 1, wherein the control system determines multiple damage locations and target healing areas, assigns a damage value to each damage location, and prioritizes activation and deactivation of the individual discrete heating elements of each target healing area according to the damage values of each damage location.

15. The self-healing system of claim 1, wherein the damage detecting system is a continuous health and performance monitoring system.

16. The self-healing system of claim 15, wherein the continuous health and performance monitoring system comprises an embedded piezoelectric sensor system.

17. The self-healing system of claim 1, wherein the control system is a computer control system interfaced with the sensor grid array.

18. The self-healing system of claim 17, wherein the computer control system:

a. compares a baseline data set against a first new data set;

b. determines a healing process based on the comparison between the baseline data set and first new data set;

c. creates a set of tasks capable of being carried out in the proper sequence by a machine to execute a healing process; and

d. compares the baseline data set against a second new data set to determine when the healing process is complete.

19. The self-healing system of claim 1, wherein the individual discrete heating elements are etched foil heaters.