Development of a Novel Health Monitoring System for Adhesively Bonded Composite Joints Using Electro-Magnetic
Abstract
Abstract Composites used in aircraft and other naval platforms, allow for a reduction in weight and an increase in operational efficiency. Adhesive bonding has become one of the major processing and fabrication technologies in the manufacturing of primary structures for these systems. Surface contamination and water ingress at the bonding interface have been identified as two of the most detrimental factors that cause debonding and structure failures of aero-structures. Existing damage detection technologies including X-ray, ultrasonic, acoustic emission, lamb wave, and thermography may be able to detect mechanical or geometrical defects in typical maintenance service operations. However, the chemically weakened or fatigued interface of an adhesive bond cannot be detected with these technologies. Some of these chemically weakened interfaces are deemed to have good geometrical integrity in the adhesive bonds while the molecular bonds formed at the interfaces are significantly weakened. Because the chemical process usually generates or consumes electrons that can be transported by mediators in the bond to or from electrodes or probes, the bond weakening process may be detected with active or passive electrochemical sensors. Thus, the proposed research is aimed at developing and studying a novel health monitoring technology that utilizes magneto-electric nanoparticles for infield and on-board monitoring of adhesive bonds. The objectives of the research are 1) to identify mediators that can effectively transport electrons or chemical states and are amenable to the adhesive bond in terms of mechanical strength; 2) to design and fabricate a novel time-resolved electrochemical wave sensor to detect and locate water ingress and chemical attacks at the bond interface; 3) to establish numerical models for analysis of electrochemical waves in a solid medium; 4) to validate the technology via correlation between chemical attack and degradation of mechanical strength of adhesive bonds. Safety of aircraft is the highest priority of the aerospace industry. Existing in-field structure integrity inspection methods can only detect relatively large geometrical defects (e.g. cracks) in the magnitude of millimeters. The significantly weakened adhesive bonds or the so-called ÒkissingÓ bonds cannot be detected as a defect by the existing methods and may fail under a mechanical load and/or environmental attack. The electrochemical wave sensor not only detects progress of the weakening process, but also can determine the location where the weakening process is occurring. The electrochemical wave technology may utilize an active or passive onboard sensor set-up for the constant monitoring of the health level of aircrafts. Application of an electrochemical wave is itself, a new frontier of science and technology. Development of the theory and technology will not only benefit mechanical engineering and aerospace industry but also corrosion engineering, renewable power systems, and bio-medical technology. The Office of Naval Research as well as other Department of Defense agencies have specific needs for the development of proven techniques that can insure the production of high quality adhesively bonded composite structures. More specifically, there is a need to understand how adhesive bonds in composite structures will perform under extended loading cycles and in 2 extreme environmental conditions. Also, this need requires an understanding of the mechanisms and factors responsible for the reduction in the strength of bonds as a results of such continuous dynamic loading in such environments. Providing this understanding will enhance the reliability of composite systems for the DoD as well as other agencies and industries utilizing composite materials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 22, 2016
- Source ID
- N000141512051
Entities
People
- Dwayne Mcdaniel
Organizations
- Florida International University
- Office of Naval Research
- United States Navy