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Carbon fiber reinforced polymers are playing a key role for future aircraft structure design concepts as the newest technical developments for aircraft models B787 and A350 are showing. Due to the specific mechanical properties of this composite material and the novel manufacturing and machining techniques for large-scale CFRP made aircraft structu...
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... direction-dependent material properties of the CFRP composite determine the geometry of the components and the structural design. Fur- thermore, regarding handling and non-destructive inspection of CFRP components, it is a big difference to deal with a demonstrator scale (Fig. 1) or a very large sized structure of an industrial production line (Fig. 2). The joining together of two large segments presents a particular challenge, as the high di- mensional stability of CFRP structure components allows a tolerance of only a few micro- ns. Fuselage shells and wing segments, which are manufactured by different supplier plants that are located several hundreds or even thousands of ...
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Citations
... Composite structures have become attractive for many industrial sectors due to their good strength and stiffness per unit weight [8][9][10]. In aviation, the volume of the composite structures used in an aircraft, such as the fuselage, wings, and empennage, has risen day by day. ...
Non-destructive testing (NDT) of aerospace structures has gained significant interest, given its non-destructive and economic inspection nature enabling future sustainable aerospace maintenance repair operations (MROs). NDT has been applied to many different domains, and there is a number of such methods having their individual sensor technology characteristics, working principles, pros and cons. Increasingly, NDT approaches have been investigated alongside the use of data fusion with the aim of combining sensing information for improved inspection performance and more informative structural health condition outcomes for the relevant structure. Within this context, image fusion has been a particular focus. This review paper aims to provide a comprehensive survey of the recent progress and development trends in NDT-based image fusion. A particular aspect included in this work is providing critical insights on the reliable inspection of aerospace composites, given the weight-saving potential and superior mechanical properties of composites for use in aerospace structures and support for airworthiness. As the integration of NDT approaches for composite materials is rather limited in the current literature, some examples from non-composite materials are also presented as a means of providing insights into the fusion potential.
... taxonomies and ontologies [20], are gaining importance and may greatly contribute to rule-driven manufacturing control [21]. In addition to the software and information technology infrastructure presently being developed, hardware that facilitates the gathering of precise in-process data from all process steps will be needed as a third pillar [18,22,23] within less than a decade. These intelligent hardware elements of machines and devices such as sensors and actuators contribute to the "field-level" base of the industrial automation pyramid [19,24], which highlights the numerous components and pathways of industrial communications, as sketched in Fig. 1.1. ...
... The use of CFRP as an innovative material for aircraft design has increased immensely within the few last years [22,29,62] (the Airbus A350 XWB is composed of up to 53% CFRP), leading to an increasing demand for both high quality and quantity of composite material and composite joints, accompanied by lower costs. Adhesive bonding as a joining technology can enable the use of the full potential of CFRP as a lightweight material for aircraft design and is already used for joining many CFRP-based aircraft parts. ...
The first chapter highlights the relevance of both adhesive bonding technology and in-process quality assessment for mastering twenty-first-century challenges in joining functional and lightweight materials like carbon fibre reinforced polymers. The ongoing developments of the relevant technological and regulatory procedures and frameworks are hereby outlined, following trends for data-driven innovation and standardisation. Advances from monitoring process variables towards the in-depth and objective Extended Non-destructive Testing (ENDT) of material-related features are presented, based on methodological and technological innovation and insights from recent European joint research projects like Horizon 2020s ComBoNDT—“Quality assurance concepts for adhesive bonding of aircraft composite structures by advanced NDT”. Introducing ten heuristic principles for quality assessment in bonding processes, a concept is demonstrated for establishing empirically consolidated sets of quantitative material and process-specific correlations between design-relevant joint features and quality data measured during the manufacture or repair of adhesive joints using ENDT. Each correlation is obtained by systematically introducing disturbances of relevant process features identified by experts and is levelled once by linking findings from standardised mechanical tests with ENDT results obtained for joints that have intentionally been manufactured or repaired in an off-specification way. Subsequent chapters will demonstrate the suitability of the broadly applicable process.
... Inferred Thermography is predominately being used to detect subsurface defects in a plethora of structural elements and mechanical systems [1]. It is one of the newest non-destructive technologies and has proven to provide substantial improvements in performance as well as good cost savings, the method allows more frequent maintenance with minimal manpower [16]. ...
Aircraft manufacturers are constantly improving their aircraft ensuring they are more cost-efficient to do this the weight of the aircraft needs to be reduced, which results in less fuel required to power the aircraft. This has led to an increased use of composite materials within an aircraft. Carbon fibre reinforced polymer (CFRP) composite is used in industries where high strength and rigidity are required in relation to weight. e.g. in aviation – transport. The fibre-reinforced matrix systems are extremely strong (i.e. have excellent mechanical properties and high resistance to corrosion). However, because of the nature of the CFRP, it does not dint or bend, as aluminium would do when damaged, it makes it difficult to locate structural damage, especially subsurface. Non-Destructive Testing (NDT) is a wide group of analysis techniques used to evaluate the properties of a material, component or system without causing damage to the operator or material. Active Thermography is one of the NDT risk-free methods used successfully in the evaluation of composite materials. This approach has the ability to provide both qualitative and quantitative information about hidden defects or features in a composite structure. Aircraft has to undergo routine maintenance – inspection to check for any critical damage and thus to ensure its safety. This work aims to address the challenge of NDT automated inspection and improve the defects’ detection by performing automated aerial inspection using a Unmanned Aerial Vehicle (UAV) thermographic imaging system. The concept of active thermography is discussed and presented in the inspection of aircraft’s CFRP panels along with the mission planning for aerial inspection using the UAV for real time inspection. Results indicate that this inspection approach could significantly reduce the inspection time, cost, and workload, whilst potentially increasing the probability of detection.
... Reference [21] inspects the dry fiber construction in view of possible errors with the approaches of non-destructive testing. An alternative approach checks the position of the textiles after the laying process step using vision [22] or laser sensors [23]. Due to the specified increase of the reject costs along the fabrication process and the determination of the fiber orientation at the handling process, there exists the demand to perform the quality assurance – as an early process step – during the handling process. ...
The advantages of Carbon fiber reinforced composites (CFRC) lead to an increasing demand of Carbon fiber products. This class of materials is gaining widespread acceptance in various fields like aviation, wind energy or automotive and is gradually replacing traditional lightweight construction materials such as high-strength steel or aluminum. Currently, particular process steps of the production of fiber composite structures are performed manually or semi-automatically. Especially the automated handling of semi-finished products consisting unstable textile poses a challenge for an economical manufacturing. The reasons for the missing automation are beside the lacking technical feasibility most of all, reliability issues during process execution, representing key aspects for potential large-scale production. As a consequence, the integration of sensor systems constitutes a promising approach for process optimization and quality assurance. In order to catch the intricate nature of possible defects and their interdependences during the single steps of the handling process, an approach for selecting, assembling and integrating the ideal sensors at the respective processing station to monitor dominant defects is presented. For this purpose, possible defects and flaws are derived from a comprehensive process analysis and accordingly suitable sensor principles are selected. The application of this approach is exemplarily demonstrated on an automotive case study focusing the separating and draping steps of flat carbon fiber textiles in a mold for a resin transfer molding (RTM) process.
... It was also used to test Apollo lunar module propellant tanks and various aerospace applications (Gholizadeh, Leman, and Baharudin 2015). Several recent studies on AE in aircraft manufacturing can also be found in (Awerbuch et al. 2016;Mendoza et al. 2013Mendoza et al. , 2014Ullmann et al. 2010). According to AE characteristics in this study the following conclusions were reached: ...
This study assesses the progression of damage occurring on glass fiber reinforced polyester composite specimens using acoustic emission (AE) parameters. Its aims are to improve understanding of the particular characteristics of AE signals; and also to determine the relationship between AE signals and the failure of the material. Time and frequency domain trends were analysed at four different applied loads (60.97, 67.75, 74.52 and 81.30 MPa) representing 45–60% of the ultimate tensile strength of material. The relevant AE parameters were analysed both in the early stages of the test and as the material neared the fracture zone. The results showed a high degree of correlation between the root mean square and number of hits AE values and the number of cycles to failure, of 92.99 and 92.19%, respectively. This correlation, as well as AE basic parameters, suggests that AE can be a valuable tool to predict the fatigue life and detect the onset of damage in such composite materials.
... Nevertheless, a standardised inspection procedure depending on the actual thermographic testing exercise is currently non- existent [3]. Active thermography is capable of being employed during [4] and after the manufacturing process as well as concerning in-service testing in particular [5, 6, 7]. [1] declares typical stages extracted from a CFRP component lifecycle in which the application of NDE by active thermography is feasible. ...
The current development trend in automotive engineering as well as in aviation features an increased substitution of metal components by carbon fibre reinforced plastic (CFRP) structures. However, material-specific requirements make a complete replacement of a metal construction by CFRP structures impracticable. Consequently, metallic regions remain in the CFRP base body as metal joints or reinforcements. Frequently, these hybrid transition areas are involved with an increased quality concern. This research explores the methodological deduction of test specimens which allow an thermographic investigation of typical defects based on predefined industrial CFRP machine elements concretely (shaft coupling, hollow shaft, gripper arm). Thereby, the optimisation through systematic parameter variation and the structured parameter documentation in a database are focused within the present research. By deriving inspection task-specific user guidelines, the predominantly manual thermographic testing process can be considerably accelerated.
... For saving manufacturing costs, it is important to detect material defects as soon as possible in order to avoid further processing with faulty structure parts that in the end cannot be used at all. The principal ideas of automated and process integrated quality assurance (PIQA) of a CFRP production line were previously described in earlier publications [1] [2] [3]. ...
... For saving manufacturing costs, it is important to detect material defects as soon as possible in order to avoid further processing with faulty structure parts that in the end cannot be used at all. The principal ideas of automated and process integrated quality assurance (PIQA) of a CFRP production line were previously described in earlier publications123. ...
Fundamental knowledge of process parameters for the manufacturing of fibre reinforced composites is essential for design and engineering of high performance lightweight structures. This concerns oxide and non-oxide fibre reinforced ceramics (CMC) as well as reinforced polymers (e.g. CFRP). The manufacturing of a layered fibre reinforced composite structure is similar to a primary shaping process and demands an efficient and consistently process monitoring to ensure sufficient quality standards. Consequently, more detailed non-destructive investigations focusing the composite’s microstructure combined with the acquired knowledge of critical manufacturing process parameters are necessary. Optically excited lock-in thermography is a qualified and proven inspection technique that provides valuable information of the composite material’s microstructure. For more sophisticated signal interpretation, the lock-in thermography measurement results are compared with other non-destructive evaluation (NDE) techniques as reference.
... In recent years, composite structures are increasingly used in strength-critical applications in aircraft, requiring more effective NDE methods. These materials, however, have high stress wave attenuation characteristics and AE has encountered stiff barriers against its uses in the aircraft industry [1,2]. Problems are mounted as typical composites are used in anisotropic sheets, requiring more elaborate Lamb-wave theories than usual ultrasonic body or surface waves. ...
The use of acoustic emission (AE) technique for detecting and monitoring damages and the
progress on damages in different structures is widely used and has earned a reputation as one of the most
reliable and well-established technique in non-destructive testing (NDT). Acoustic Emission is a very
efficient and effective technology used for fracture behavior and fatigue detection in metals, fiberglass,
wood, composites, ceramics, concrete and plastics. It can also be used for detecting faults and pressure leaks
in vessels, tanks, pipes, as well as for monitoring the progression of corrosion in welding. This paper
reviews major research developments over the past few years in application of acoustic emission in
numerous engineering fields, including manufacturing, civil, aerospace and material engineering.
Two aircraft wings made of carbon fiber-reinforced plastic material were inspected using the laser-based ultrasonic propagation imaging system for the visualization of manufacturing defect and damages of debonding mode. Hypotheses of the detection mechanism of composite debonding were presented and validated through the inspection results for the bonding lines of the composite wing structures. The inspection showed that the location, shape, and size of the poor bonding defect, artificial stringer tip debonding, and real skin–spar debonding can be visualized and/or measured from the imaging results. The performance of the imaging system was found better than that of a manual ultrasonic C-scan in terms of spatial resolution and damage detectability. Another finding from the inspection was the occurrence of skin buckling between two riveted locations. Most importantly, the presence of structural elements or features such as spars, stringers, ribs, lugs, inspection windows, and even embedded PZT elements did not adversely affect the inspection.
