SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  AF071-120 (AirForce)
Title:  Damage Detecting Appliques for Composite Structure
Research & Technical Areas:  Air Platform, Materials/Processes

  STATEMENT OF INTENT: Improve damage detection appliques for composites
  Objective:  Develop a self-adhesive applique film that contains pressure/impact sensitive additives to detect mechanical impact that can cause damage and/or delamination of underlying composite structure.
  Description:  Inspection of composite aircraft structure for impact damage is difficult and time consuming. Research in multifunctional coating systems has shown promise for diagnostic capabilities. Corrosion sensing is of interest in aluminum structure. Composite aircraft skins are subject to low-impact damage, which can result in subsurface delamination. This type of damage is time consuming to inspect for and is thus, costly. Condition based maintenance is desired to reduce maintenance cost and increase mission readiness. Automated damage detection is required to facilitate condition-based maintenance. Applique films, which are under consideration as replacements for traditional paint-based coating systems in newer military aircraft, offer potential for in-situ sensing. A diagnostic applique film is desired that can detect impact damage in composite substrates. The diagnostic applique must meet the requirements of typical aircraft coating systems including signature properties, cleanability, and durability. The applique should adhere tenaciously to the composite structure over the extremes of aircraft operation (e.g., -55 to 175 C).

  PHASE I: The Phase I product will include the development, demonstration, and limited experimental validation of diagnostic applique for impact detection.
  
  PHASE II: The product from Phase I would be further developed and validated over a range of impact conditions. A probability of detection (POD) study will be conducted to quantify damage detectability. Environmental exposure and temperature cycling tests will be performed to indicate long term durability.

  DUAL USE COMMERCIALIZATION: Military application: Technology developed under this program should have widespread application for both military and commercial aircraft. Commercial application: Technology developed under this program should have widespread application for both military and commercial aircraft.

  References:  1. John M. Brupbacher, “Multi-Functional Applique for Corrosion Control,” Proceedings 2003 Tri-Service Corrosion Conference, Las Vegas, Nevada, 17-21 November 2003. 2. Y. Zhang, “Dynamic Strain Measurement Using Piezoelectric Paint,” Structural Health Monitoring 2003 Edited by Fu-Kuo Chang, DEStech Publications, 2003. 3. http://assist.daps.dla.mil/quicksearch/; Conduct a search for MIL-HDBK-17; Proceed to Volume 3, Chapter 7: Damage Resistance, Durability, and Damage Tolerance for guidance on detection criteria.

Keywords:  applique, damage detection, composite structure, self-adhesive film

Additional Information, Corrections, References, etc:
The following industry engineers have expressed interest in being points of contact for their respective companies in addressing questions of the proposers:

Larry Hebert, 3M Aerospace & Aircraft Maintenance, 651-575-3831, lshebert@mmm.com

Doug Ward, GE Aircraft Engines, (513) 243-7184, doug.ward@ge.com

Charlie Watson, Pratt & Whitney, 860-565-0118, charles.watson@pw.utc.com (health monitoring of critical composite ducts and cases)

Appliques are of interest as a replacement for paint on aircraft external surfaces, and the case of this topic, for health monitoring of critical damage-sensitive areas.

Only impact-detecting schemes contained in an applique system (applique+adhesive) are of interest in this particular topic.

Electromagnetic signature (stealth) can be affected by incorporation of electromagnetically-active materials in the applique system. If the signature is affected by a proposed solution, it is viable only for non-stealth aircraft, which generally excludes the newer systems.

Electromagnetically-active materials may be ok at levels of a few percent or less. The safest approach re potential effects of electromagnetically-active materials is to provide data indicating insignificant effects can be aniticipated on the aircraft electromagnetic signature. Additional questions can be addressed publically through SITIS, while limiting answers to non-sensitive information.

Additional functionalities beyond impact detection are not required but may confer additional interest to the proposal if in fact some kind of probability of success can be inferred, otherwise additional risk may be unwarranted.

While impact indications in the visible spectrum are ok if required, some kind of easily applied affordable instrument required to reveal their presence is preferred.

Relevant impact energy levels are as follows:
6 ft-lb (corresponds to tool drop, runway debris, hail, etc) - this is pretty low.
100 ft-lb - general cutoff for consideration of damage tolerance, corresponds to a tool box dropped from waist-high. This is a pretty large number for composites, i.e. one would want to detect damage at much lower levels than this.

Thresholds of interest may lie anywhere between these numbers (6-100 ft-lbs), depending on application. A system that can indicate more than one threshold may be useful.
The following industry engineers have expressed interest in being points of contact for their respective companies in addressing questions of the proposers:

Larry Hebert, 3M Aerospace & Aircraft Maintenance, 651-575-3831, lshebert@mmm.com

Doug Ward, GE Aircraft Engines, (513) 243-7184, doug.ward@ge.com

Charlie Watson, Pratt & Whitney, 860-565-0118, charles.watson@pw.utc.com (health monitoring of critical composite ducts and cases)

Appliques are of interest as a replacement for paint on aircraft external surfaces, and the case of this topic, for health monitoring of critical damage-sensitive areas.

Only impact-detecting schemes contained in an applique system (applique+adhesive) are of interest in this particular topic.

Electromagnetic signature (stealth) can be affected by incorporation of electromagnetically-active materials in the applique system. If the signature is affected by a proposed solution, it is viable only for non-stealth aircraft, which generally excludes the newer systems.

Electromagnetically-active materials may be ok at levels of a few percent or less. The safest approach re potential effects of electromagnetically-active materials is to provide data indicating insignificant effects can be aniticipated on the aircraft electromagnetic signature. Additional questions can be addressed publically through SITIS, while limiting answers to non-sensitive information.

Additional functionalities beyond impact detection are not required but may confer additional interest to the proposal if in fact some kind of probability of success can be inferred, otherwise additional risk may be unwarranted.

While impact indications in the visible spectrum are ok if required, some kind of easily applied affordable instrument required to reveal their presence is preferred.

Relevant impact energy levels are as follows:
6 ft-lb (corresponds to tool drop, runway debris, hail, etc) - this is pretty low.
100 ft-lb - general cutoff for consideration of damage tolerance, corresponds to a tool box dropped from waist-high. This is a pretty large number for composites, i.e. one would want to detect damage at much lower levels than this.

Thresholds of interest may lie anywhere between these numbers (6-100 ft-lbs), depending on application. A system that can indicate more than one threshold may be useful.

Questions and Answers:

No questions posed on this topic at this time

Record: of