Browsing by Author "Tinsley, Lawrence"
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Item Open Access A coefficient clustering analysis for damage assessment of composites based on pulsed thermographic inspection(Elsevier, 2016-06-11) Zhao, Yifan; Tinsley, Lawrence; Addepalli, Sri; Mehnen, Jorn; Roy, RajkumarThis paper introduces a coefficient clustering analysis method to detect and quantitatively measure damage occurring in composite materials using pulsed thermographic inspection. This method is based on fitting a low order polynomial model for temperature decay curves, which (a) provides an enhanced visual confirmation and size measurement of the damage, (b) provides the reference point for sound material for further damage depth measurement, (c) and reduces the burden in computational time. The performance of the proposed method is evaluated through a practical case study with carbon fibre reinforced polymer (CFRP) laminates which were subjected to a drop impact test with varying energy levels. A novel method for reducing an entire thermogram sequence into a single image is introduced, which provides an enhanced visualisation of the damage area.Item Open Access Detectability evaluation of attributes anomaly for electronic components using pulsed thermography(Elsevier, 2020-09-16) Liu, Haochen; Tinsley, Lawrence; Addepalli, Sri; Liu, Xiaochen; Starr, Andrew; Zhao, YifanCounterfeit Electronic Components (CECs) pose a serious threat to all intellectual properties and bring fatal failure to the key industrial systems. This paper initiates the exploration of the prospect of CEC detection using pulsed thermography (PT) by proposing a detectability evaluation method for material and structural anomalies in CECs. Firstly, a numerical Finite Element Modelling (FEM) simulation approach of CEC detection using PT was established to predict the thermal response of electronic components under the heat excitation. Then, by experimental validation, FEM simulates multiple models with attribute deviations in mould compound conductivity, mould compound volumetric heat capacity and die size respectively considering experimental noise. Secondly, based on principal components analysis (PCA), the gradients of the 1st and 2nd principal components are extracted and identified as two promising classification features of distinguishing the deviation models. Thirdly, a supervised machine learning-based method was applied to classify the features to identify the range of detectability. By defining the 90% of classification accuracy as the detectable threshold, the detectability ranges of deviation in three attributes have been quantitively evaluated respectively. The promising results suggest that PT can act as a concise, operable and cost-efficient tool for CECs screening which has the potential to be embedded in the initial large scale screening stage for anti-counterfeit.Item Open Access Effect of extrusion and compression moulding on the thermal properties of nylon-6/silica aerogel composites(SAGE, 2017-10-03) Krishnaswamy, Suryanarayanan; Tinsley, Lawrence; Marchante, Veronica; Addepalli, Sri; Huang, Zhaorong; Abhyankar, HrushikeshThe article presents the effect of a lower extrusion speed and compression moulding processes on the thermal properties of polyamide 6 (PA-6)/aerogel composite. Scanning electron and optical microscope images showed that although most of the aerogel was destroyed during extrusion at 65 r/min, extrusion at 5 r/min showed a better retention of the aerogel structure. However, when subjected to moulding in a compression press, both composites extruded at different speeds suffered significant damage. Nevertheless, the extruded samples did show a lower thermal conductivity compared to the virgin polymer. Further, it was observed that the sample extruded at 5 r/min had a lower damage coefficient value with an overall loss of around 33% to the aerogel structure when compared to the material extruded at 65 r/min, which endured a structural loss of 41% to the aerogel in it.Item Open Access Effect of extrusion and compression moulding on the thermal properties of Nylon-6/Silica Aerogel Composites: Experimental Data(Cranfield University, 2017-10-05 16:38) Krishnaswamy, Surya; Tinsley, Lawrence; Marchante, Veronica; Addepalli, Sri; Huang, Zhaorong; Abhyankar, HrushikeshThe paper presents the effect of a lower extrusion speed and compression moulding on the thermal properties of PA-6/Aerogel composite. SEM/EDX and optical microscope images showed that although most of the aerogel was destroyed during extrusion at 65 rpm, extrusion at 5 rpm showed better retention of the aerogel structure. However, when subjected to moulding in a compression press, both composites suffered significant damage. Nevertheless, the final thermal conductivity and damage coefficient values did show an improvement in the thermal insulation properties of the samples extruded at 5 rpm compared to the samples extruded at 65 rpm and the virgin polymer (PA-6) with the former losing around 33% of the structure of the aerogel particles compared to 41% for the later.Item Open Access A fiber-guided motorized rotation laser scanning thermography technique for impact damage crack inspection in composites(IEEE, 2023-04-11) Liu, Haochen; Tinsley, Lawrence; Deng, Kailun; Wang, Yizhong; Starr, Andrew; Chen, Zhenmao; Zhao, YifanLaser Thermography manifests superior sensitivity and compatibility to detect cracks and small subsurface defects. However, the existing related systems have limitations on either inspection efficiency or unknown directional cracks due to the utilization of stationary heat sources. This article reports a Fiber-guided Motorised Rotation Laser-line Scanning Thermography (FMRLST) system aiming to rapidly inspect cracks of impact damage with unknown direction in composite laminates. An optical head with fibre delivery integrated with a rotation motor is designed and developed to generate novel scanning heating in a circumferential rotation manner. A FEM model is first proposed to simulate the principle of FMRLST testing and produce thermograms for the development of post-processing methods. A damage enhancement method based on Curvelet Transform is developed to enhance the visualization of thermal features of cracks, and purify the resulting image by suppressing the laser-line heating pattern and cancelling noise. The validation on three composite specimens with different levels of impact damage suggests the developed FMRLST system can extract unknown impact surface cracks efficiently. The remarkable sensitivity and flexibility of FMRLST to arbitrary cracks, along with the miniaturized probe-like inspection unit, present its potential in on-site thermographic inspection, and its design is promising to push the LST towards.Item Open Access Inspection of electronic component using pulsed thermography(Elsevier, 2021-07-14) Tinsley, Lawrence; Liu, Haochen; Addepalli, Sri; Lam, Wayne; Zhao, YifanCounterfeit electronic components (CEC) are of great concern to governments and industry globally as they could lead to systems and mission failure, malfunctioning of safety critical systems, and reduced reliability of high-hazard assets. Depending on the cost of CEC going into the production line, some industries might look to have some sort of inspection capability in-house to screen critical components before they go to assembly. Although advanced counterfeit inspection methods have been developed for a variety of components, they generally exhibit a combination of disadvantages such as destructive, low throughput, high unit cost, or inaccessible to unskilled operator. This paper investigates the potential of pulsed thermography on detection of CEC in a fast and non-destructive manner. The second derivative of post-heat thermal response is used to construct a fingerprint to differentiate genuine and counterfeit components. Results successfully demonstrate the potential of the proposed solution.Item Open Access A novel inspection technique for electronic components using thermography (NITECT)(MDPI, 2020-09-03) Liu, Haochen; Tinsley, Lawrence; Lam, Wayne; Addepalli, Sri; Liu, Xiaochen; Starr, Andrew; Zhao, YifanUnverified or counterfeited electronic components pose a big threat globally because they could lead to malfunction of safety-critical systems and reduced reliability of high-hazard assets. The current inspection techniques are either expensive or slow, which becomes the bottleneck of large volume inspection. As a complement of the existing inspection capabilities, a pulsed thermography-based screening technique is proposed in this paper using a digital twin methodology. A FEM-based simulation unit is initially developed to simulate the internal structure of electronic components with deviations of multiple physical properties, informed by X-ray data, along with its thermal behaviour under exposure to instantaneous heat. A dedicated physical inspection unit is then integrated to verify the simulation unit and further improve the simulation by taking account of various uncertainties caused by equipment and samples. Principle component analysis is used for feature extraction, and then a set of machine learning-based classifiers are employed for quantitative classification. Evaluation results of 17 chips from different sources successfully demonstrate the effectiveness of the proposed techniqueItem Open Access Pulse thermography-based ageing assessment of thin thermal barrier coatings.(Cranfield University, 2019-06) Tinsley, Lawrence; Zhao, Yifan; Rajkumar, Roy; Mehnen, JornWith the motivation to drive gas turbines at increasing power and efficiency, the increase of combustion temperatures is highly desirable, while turbine temperatures are met by material limitations where the temperatures readily exceed the melting point of the metals used to make the components. In response to this, engine manufacturers implement thermal control systems, from air cooling of the component, to Thermal Barrier Coatings (TBCs) applied on the component surfaces, reflecting radiant heat energy and providing an insulating layer. These materials reduce the temperature experienced by the component materials, enabling higher operational temperatures; while the metallic bond coat in between also protects against oxidation and corrosion attack. With TBCs playing such a crucial role in the standard operation of gas turbines at the edge of its performance capability, standing between materials performing one of the most stringent engineering roles ever designed, and the hot gases capable of melting them; the durability of the TBC to resist its own degradation and their ensuing material life are vital. The assessment of TBC health and its Remaining Useful Life (RUL) are of key interest in the maintenance of aero engine components. This thesis presents a review of Non-Destructive Testing (NDT) methods utilised in the inspection of TBCs, proceeding to evaluate the use of pulsed-active flash thermography NDT for ageing assessment of thin TBCs undergoing cyclic oxidation ageing, selected for study to adapt the method to the more challenging context at the cutting edge of gas turbine performance. The coatings were inspected with and without emissivity-improving soot coating to evaluate a realistic inspection scenario – where contamination may not be justifiable – with ideal inspections performed in parallel. In order to address the challenge of capturing a fast thermal event through a thin TBC, an inspection framework was developed to optimise the data capture and analysis parameters. Through-depth diffusivity has been measured during oxidation ageing of six 150µm thick TBCs deposited via Electron Beam Physical Vapour Deposition (EB-PVD), showing a repeatable trend with distinct features, which can be exploited for ageing characterisation, with automation of thermographic NDT of TBC parts demonstrating the potential for rapid implementation of the technique. The research provides through-life captures of each of the TBC samples uniquely coupled with parallel captures in the non-ideal inspection condition without application of an emissivity improving soot coating, simulating a real-world inspection scenario in which a wide area un-treated surface inspection is desired. Additionally, a novel inspection framework has been developed for establishing the multiple coupled parameters required to tackle the complexities introduced when applying optical flash for thermography of thin EB-PVD TBCs.Item Open Access Service Knowledge Capture and Reuse(Elsevier, 2014-06-30) Roy, Rajkumar; Mehnen, Jorn; Addepalli, Sri; Redding, Louis E.; Tinsley, Lawrence; Okoh, CaxtonThe keynote will start with the need for service knowledge capture and reuse for industrial product-service systems. A novel approach to capture the service damage knowledge about individual component will be presented with experimental results. The technique uses active thermography and image processing approaches for the assessment. The paper will also give an overview of other non-destructive inspection techniques for service damage assessment. A robotic system will be described to automate the damage image capture. The keynote will then propose ways to reuse the knowledge to predict remaining life of the component and feedback to design and manufacturing.Item Open Access Thermal Diffusivity Changes of EB-PVD Thermal Barrier Coatings Undergoing Oxidation Ageing.(Cranfield University, 2020-03-13 09:59) Tinsley, Lawrence; Roy, Rajkumar; Mehnen, Jorn; Chalk, Christine; Nicholls, JohnNormalized (apparent) thermal diffusivity values for yttria-stabilised zirconia (7YSZ) Thermal Barrier Coatings undergoing isothermal oxidation ageing with data captured at 16-hour intervals.