Browsing by Author "Padiyar M, Janardhan"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Open Access Autonomous inspection and repair of aircraft composite structures(Elsevier, 2018-11-23) Kostopoulos, Vassilis; Psarras, Spyridon; Loutas, Theodoros; Sotiriadis, George; Gray, Iain; Padiyar M, Janardhan; Petrunin, Ivan; Raposo Gaudencio Campos, Joao; Zanotti Fragonara, Luca; Tzitzilonis, Vasileios; Dassios, Konstantinos; Exarchos, Dimitrios; Andrikopoulos, George; Nikolakopoulos, GeorgeThis paper deals with the development of an innovative approach for inspection and repair of damage in aeronautical composites that took place in the first two years of the H2020 CompInnova project which. The aim is a newly designed robotic platform for autonomous inspection using combined infrared thermography (IRT) and phased array (PA) non-destructive investigation for damage detection and characterization, while integrated with laser repair capabilities. This will affect the increasing societal need for safer aircraft in the lowest possible cost, while new and effective techniques of inspection are needed because of the rapidly expanding use of composites in the aerospace industry.Item Open Access Fast, accurate, and reliable detection of damage in aircraft composites by advanced synergistic infrared thermography and phased array techniques(MDPI, 2021-03-19) Padiyar M, Janardhan; Fragonara, Luca Zanotti; Petrunin, Ivan; Raposo, João; Tsourdos, Antonios; Gray, Iain; Farmaki, Spyridoyla; Exarchos, Dimitrios; Matikas, Theodore E.; Dassios, Konstantinos G.This paper presents an advanced methodology for the detection of damage in aircraft composite materials based on the sensor fusion of two image-based non-destructive evaluation techniques. Both of the techniques, phased-array ultrasonics and infra-red thermography, are benchmarked on an aircraft-grade painted composite material skin panel with stringers. The sensors systems for carrying out the inspections have been developed and miniaturized for being integrated on a vortex-robotic platform inspector, in the framework of a larger research initiative, the Horizon-2020 ‘CompInnova’ project.Item Open Access Improving depth resolution of ultrasonic phased array imaging to inspect aerospace composite structures(MDPI, 2020-02-20) Mohammadkhani, Reza; Fragonara, Luca Zanotti; Padiyar M, Janardhan; Petrunin, Ivan; Raposo, João; Tsourdos, Antonios; Gray, IainIn this paper, we present challenges and achievements in development and use of a compact ultrasonic Phased Array (PA) module with signal processing and imaging technology for autonomous non-destructive evaluation of composite aerospace structures. We analyse two different sets of ultrasonic scan data, acquired from 5 MHz and 10 MHz PA transducers. Although higher frequency transducers promise higher axial (depth) resolution in PA imaging, we face several signal processing challenges to detect defects in composite specimens at 10 MHz. One of the challenges is the presence of multiple echoes at the boundary of the composite layers called structural noise. Here, we propose a wavelet transform-based algorithm that is able to detect and characterize defects (depth, size, and shape in 3D plots). This algorithm uses a smart thresholding technique based on the extracted statistical mean and standard deviation of the structural noise. Finally, we use the proposed algorithm to detect and characterize defects in a standard calibration specimen and validate the results by comparing to the designed depth information.Item Open Access Lamb wave-based air-coupled ultrasonic inspection technique for filament-wound composite pipes(British Institute of Non-destructive Testing, 2014-04-01) Padiyar M, Janardhan; Balasubramaniam, K.Filament-wound glass epoxy composite pipe-like structures require ultrasonic inspection in order to characterise any potential defects, such as those due to foreign inclusions and delaminations, so that defective as-manufactured components do not go into service. Current manual point-to-point contact or immersion-based ultrasonic inspections are effective but time consuming and expensive for large-diameter/long-span composite pipes. This work addresses the need for rapid defect inspection for these composite pipes. The detection of multiple artificial inclusions in the pipe using the A0 Lamb wave mode, generated and received using non-contact air-coupled ultrasonic transducers, is studied in this investigation. A two-step inspection technique is proposed. The first step consists of a single-sided global screening in the axial and radial directions of the pipe using the A0 mode for rapidly locating the defects. In the second step, a limited-area point-to-point air-coupled through-transmission inspection for sizing the defects is proposed. Lamb wave-based inspections are interpreted using a two-dimensional intensity profile (B-scans), which satisfactorily indicates the approximate locations of defective regions. The aim of this study is also to demonstrate a system using this proposed Lamb wave technique.Item Open Access Quantitative characterization of interface delamination in composite T-joint using couplant-free Lamb wave methods(Sage, 2015-11-24) Padiyar M, Janardhan; Balasubramaniam, KrishnanResearch in quick Non-Destructive Evaluation methods for field maintenance of aircraft has become a focus of attention due to increase in the use of co-cured skin-stiffened composite structures. When Lamb wave propagates over skin-stiffened structure, the occurrence of multiple modes is unavoidable due to structural features such as stringers and stiffeners, which in turn makes the interpretation of the received wave difficult and limits the defect-detection ability of Lamb waves. Using Finite Element simulations, the propagation of incident S0 Lamb mode in a typical composite T-joint with delamination between the flange and skin (interface) is investigated. Arrival time delays of the out-of-plane mode-converted wave packets are found to be promising indicator for quantitative detection and sizing of the delamination. A novel experimental technique of combining a liquid couplant-free transduction scheme using dry-coupled roller transducer (contact probe) for generating S0 mode and an air-coupled transducer (non-contact probe) as a receiver is proposed. This transduction scheme helps in selectively separating mode-converted wave packets. This investigation also establishes quantitative B-scan imaging method for characterization of delamination in the T-joint. Experimental results show a good agreement with Finite Element predictions.