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Composites Evaluation in aircraft industry through Triplex IR imaging system

Final Report Summary - COMPETE (Composites Evaluation in aircraft industry through Triplex IR imaging system)

Executive Summary:
Over the last two decades the use of composites in aerospace applications has increased tremendously whilst being supported by innovative research into various aspects of composite materials. The aerospace industry thrives on cutting edge developments and is constantly striving to improve the quality of the finished product. The market for aerospace composites [1], encompassing both production, maintenance-repair-and-overhaul (MRO) services, worths $9.8 billion for 2010 with the demand for MRO to be more than €1.9 billion. The predictions about the future are that the increasing percentage of composites in new transport aircraft and the continued growth in the demand for MRO services will combine to nearly double the aerospace composites market. The EU aerospace sector consists of approximately 15,600 SMEs that offer manufacturing, composites, NDT&E, inspection and consulting services [2]. As a result, the capabilities of the approximately 15,150 SMEs in the NDT sector that use only existing methods will soon be overwhelmed as use of composites continues to grow!

The real need for development of a novel non–invasive imaging system and the genesis of this proposal came as the use of composites increase in all methods of transport and in particular in the aerospace industry. However there is a lot of conflicting or incorrect information in the aviation community about the safety and capability of fibre composite materials. Composite structures behave very differently under normal loads than equivalent metal structures. Fatigue and corrosion have been proven through trials of composite repair patches to be much less prevalent in composites compared with metals. Subsurface damage such can go undetected for long periods and result in sudden catastrophic failure [3], such as the in the crash of American Airlines Airbus A300-600 Flight 587 in November 2001. Thus, the need of a truly innovative inspection process capable of identifying the condition of these materials is becoming increasingly important. This leads to the ascertainment that an advanced automated infrared imaging tool performing inspections in a faster and more accurate manner, on aircraft composite components would provide an advantageous method to boost the business of the EU aircraft industry SMEs.
[1]. Growth Opportunities for Composites in Aerospace MRO Market 2011-2016 : Trends, Forecast and Opportunity Analysis, 2010, pp. 115
[2]. European Commission, Directorate-General Enterprise & Industry, “Competitiveness of the EU Aerospace Industry with focus on: Aeronautics Industry”, December 2009
[3]. Taylor, R., Fibre composite aircraft – capability and safety. Australian Transport Safety Bureau, Report AR-2007-021, 2008

Project Context and Objectives:
CompETe will develop an automated and advanced non-invasive imaging NDT system-integrated tool for qualitative and quantitative inspection of composites used in aircraft applications. The system will be applied using automated scanning with an innovative approach that will be operating in all three infrared wavelengths (i.e. near, medium and long wave). In particular, the advanced automated system-tool allows for fast and prompt inspection of different composite components of the aircraft transport utilizing Near Infrared Vision (i.e. inspection of transparent and semi- transparent composites), Mid Wave IR Thermography (i.e. inspection in the manufacturing and assembly stages - interior aircraft parts), and Long Wave IR Thermography (i.e. in situ inspections for maintenance and repair - exterior aircraft inspections) with the use of commercial sensors.

The proposed advanced integrated NDT system by applying imaging scanning in the three infrared wavelengths will reduce the use of manual, subjective inspections. This way, accuracy will be improved, leading to an increased “Probability of Detection” at a higher confidence level and further reduce the operating cost and time. A poly-articulated robotic arm will be utilized to apply non destructive testing (imaging scanning) on composite surfaces and the sensors on its head will perform IR Thermography and Near Infrared Imaging NDT scanning, create the appropriate scanning conditions (material energy excitation) and ensure precision and tracking of scanning process. These standard “off-the-shelf” robots have reached a very high level of reliability and appear to be ideally suited for use within the CompETe system able to satisfy all the inspection requirements. Their main advantage is in their ability to have a large range of movement (6 motion axes). The CompETe robotic arm is capable of achieving precise motion with respect to the scanned surface and further inspects surfaces of complex geometry, complying with the aeronautic specifications in terms of fast inspection speeds and accuracy, as well as of repeatability and reliability of the process. A ”smart” laser sensor attached in the robot end effector identifies and follows the sample geometry providing rotational motion of the inspection equipment and positioning vertically the end effector to the surface. Commercial sensor units, bought or rented, are used to acquire images during the non destructive inspection of composites in the three infrared wavelengths, installed on the manipulator’s end effector. The scanner is surrounded by excitation sources (thermal sources, lights), required for the application of imaging techniques inspections. The CompETe robot head offers multi-sensor flexibility and customisation options for the adaptation of a variety of different commercial IR cameras. Multiple commercial imaging sensors will be able to be integrated in the chassis in a modular fashion and can be rapidly interchanged.

The ultimate objective of this project is the delivery of an advanced prompt non-destructive monitoring and assessment system for detecting and evaluating damage of composite surfaces in aircraft industry and at the same time, a cost effective tool to optimize the maintenance schedule and reducing the average life-cycle costs. Unnecessary manual and subjective inspections would be reduced and/or eliminated, accuracy will be improved via the development and validation of an automated and non-invasive scanning NDT tool (for qualitative and quantitative assessment), making it cost effective for inspection and maintenance processes.

Project Results:
The CompETe system available at the end of the project consists of four main categories of components:

- The relocatable robotic cell with the robotic arm
- The robotic (head) effector with the positioning system
- The distributed software platform composed of three subsystems
--- Data acquisition and management
--- Post-processing and image analysis
--- Control of the robot
- Instrumentation: off-the-shelf cameras, lamps, etc.

Note that the first three categories (relocatable robotic cell, robotic (head) effector and distributed software platform) were developed specifically for the project, while the latter category (instrumentation) consists of additional commercial equipments that can be bought, rented or made available free of charge.

The CompETe system employs advanced imaging NDT methods and procedures for composites’ assessment in manufacturing, assembly and maintenance/repair stages. The new equipment is capable to inspect composite materials and structures operating in the three infrared wavelengths (involving Near Infrared Vision, Mid Wave Thermography and Long Wave Thermography) and provide defect assessment by quantitative means of different composite components (CFRP, GFRP, etc) in various air transport applications.
Potential Impact:
The market for aerospace composites, encompassing both production and maintenance, repair and overhaul (MRO) services is by the AeroStrategy’s 2009 estimate worth $7.3 billion. Demand for MRO service of composite components, such as repair of thrust reversers, radomes, nacelles, control surfaces, structural components and cabin interiors, is sizable at €1.8 billion, and it’s growing. The predictions about the future are that the increasing percentage of composites in new transport aircraft and continued growth in the demand for MRO services will combine to nearly double the aerospace composites market. The belief is that the market will reach €9.8 billion till 2016 at a compound annual growth rate of nearly 7%. The next decade (2016-2026) the increase in the composite market is believed to be sharper. The non-destructive testing (NDT) and inspection market size was valued at USD 6.46 Billion in 2015 and is expected to increase to $11.39 Billion by 2022, at a compound annual growth rate of 8.30% between 2016 and 2022. Moreover, the global Non Destructive Testing Equipment market would register a revenue of $2.2 billion by 2022, growing at a compound annual growth rate of 8.7% during the forecast period.

Within the NDT community, development teams are focusing on finding tools and strategies to help the future NDT operators to detect and quantify potential internal structural variations of composite materials in fast and accurate manner.

The novel system will offer its customers quantitative imaging inspection for composites defect assessment, fast, reliable and fully-automated detection of different types of defects, assessment of the aircraft composites parts in manufacturing and assembly stages and during the maintenance and repair stages and procedures for using imaging NDT integrated methodology in non-destructive assessment of composites and composite repairs on air transport applications. The CompETe system is based on pattern recognition and computational intelligence algorithms something that is really innovative and hopefully very useful for automated flaw detection in composites.

List of Websites:
Contact: Mr Patrik Karlsson, CITY University London
Contact: Prof. Nicos Karcanias