Defect Detection in Synthetic Fibre Ropes using Detectron2 Framework

Fibre ropes with the latest technology have emerged as an appealing alternative to steel ropes for offshore industries due to their lightweight and high tensile strength. At the same time, frequent inspection of these ropes is essential to ensure the proper functioning and safety of the entire system. The development of deep learning (DL) models in condition monitoring (CM) applications offers a simpler and more effective approach for defect detection in synthetic fibre ropes (SFRs). The present paper investigates the performance of Detectron2, a state-of-the-art library for defect detection and instance segmentation. Detectron2 with Mask R-CNN architecture is used for segmenting defects in SFRs. Mask R-CNN with various backbone configurations has been trained and tested on an experimentally obtained dataset comprising 1,803 high-dimensional images containing seven damage classes (loop high, loop medium, loop low, compression, core out, abrasion, and normal respectively) for SFRs. By leveraging the capabilities of Detectron2, this study aims to develop an automated and efficient method for detecting defects in SFRs, enhancing the inspection process, and ensuring the safety of the fibre ropes.Comment: 12 pages, 7 figures, 4 table

Condition Monitoring Technologies for Steel Wire Ropes – A Review

In this research, we review condition-monitoring technologies for offshore steel wire ropes (SWR). Such ropes are used within several offshore applications including cranes for load handling such as subsea construction at depths up to 3-4000 meters, drilling lines, marine riser tensioner lines and anchor lines. For mooring, there is a clear tendency for using fiber ropes. Especially for heavy-lift cranes and subsea deployment, winches with strong ropes of up to 180 mm in diameter may be required, which has a considerable cost per rope, especially for large water depths. Today’s practice is to discard the rope after a predetermined number of uses due to fatigue from bending over sheaves with a large safety factor, especially for systems regulated by active heave compensation (AHC). Other sources of degradation are abrasion, fretting, corrosion and extreme forces, and are typically accelerated due to undersized or poorly maintained sheaves, groove type, lack of lubrication and excessive load. Non-destructive testing techniques for SWR have been developed over a period of 100 years. Most notably are the magnetic leakage techniques (electromagnetic methods), which are widely used within several industries such as mining and construction. The content reviewed in this research is primarily the developments the last five years within the topics of electromagnetic method, acoustic emissions (AE), ultrasound, X- and γ-rays, fiber optics, optical and thermal vision and current signature analysis. Each technique is thoroughly presented and discussed for the application of subsea construction. Assessments include ability to detect localized flaws (i.e. broken wire) both internally and externally, estimated loss of metallic cross sectional area, robustness with respect to the rough offshore environment, ability to evaluate both rope and end fittings, and ability to work during operation

Nondestructive Testing in Composite Materials

In this era of technological progress and given the need for welfare and safety, everything that is manufactured and maintained must comply with such needs. We would all like to live in a safe house that will not collapse on us. We would all like to walk on a safe road and never see a chasm open in front of us. We would all like to cross a bridge and reach the other side safely. We all would like to feel safe and secure when taking a plane, ship, train, or using any equipment. All this may be possible with the adoption of adequate manufacturing processes, with non-destructive inspection of final parts and monitoring during the in-service life of components. Above all, maintenance should be imperative. This requires effective non-destructive testing techniques and procedures. This Special Issue is a collection of some of the latest research in these areas, aiming to highlight new ideas and ways to deal with challenging issues worldwide. Different types of materials and structures are considered, different non-destructive testing techniques are employed with new approaches for data treatment proposed as well as numerical simulations. This can serve as food for thought for the community involved in the inspection of materials and structures as well as condition monitoring

The development of condition monitoring strategies and techniques appropriate to mechanical structures.

Recent legislation, LOLER, removed the compulsion of periodical proof testing of lifting equipment to ascertain its "fitness for purpose". It has become the responsibility of a competent person to assess equipment's fitness for purpose and ability for continued safe use. This thesis reviews the technologies available to the competent person to enable him/her to come to an informed decision regarding the condition of mechanical structures. It was identified that an optimal methodology would interrogate structural integrity whilst the equipment performed its intended function. Coupling a means of assessment with the equipment's operation allows the investigator to focus on only defective conditions that will limit the future operation. Such an approach of condition monitoring structural integrity as opposed to employing traditional methods of inspection that are essentially failure finding tasks permits the discrimination between benign and malignant defects. Restorative and replacement activities can therefore take place based upon the likelihood of equipment's functional failure. The supplementary monitoring of Acoustic Emission (AE), with the established industrial practice of proof testing, was considered to provide data to monitor structural integrity and provide the basis upon which a structure can be re-qualified for future service. The nature of failure of engineering materials was examined which identified failure modes such as corrosion, creep and fatigue resulted in a progressive degradation of a localised area. The AE is a proportion of energy released during such deterioration. Further it was determined that the rate at which the deterioration increased was non-linear. Within a laboratory environment wire ropes with seeded faults were subjected to a simulated life during which the qualitative and quantitative nature of the AE was investigated.It was found that the quantity of the emission generated during proof tests was indicative of the severity of the induced defect. This substantiated the claim that AE could be used to enhance the proof test and provide a means by which a condition assessment could be made at intervals throughout the life of a structure. A series of five case studies explored the use of AE on a variety of differing in-service mechanical structures, mostly lifting equipmept. The case studies were conducted on pad-eyes,link-plates, cranes, both Electrical Overhead Travelling (EOT) and pedestal cranes and finally, an underwater vehicle pressure hull. The approach of using the combination of AE with a proof test was verified in the cases of pad-eyes and EOT cranes. In the instance of link plates, simultaneous measurement of strain and AE during a load test demonstrated the ability of AE to detect localised yielding. During the destruction test of a pedestal crane boom section, various conventional methods of AE evaluation were utilised to investigate which would provide the most reliable condition indicator; it was found that Intensity Analysis generated the most effective trendable measurement. A study on a pressure hull with known fatigue cracks that were subjected to both static and dynamic testing whilst monitoring with AE was conducted. The fatigue cracks were sized pre and post the trial using Time of Flight Diffraction (ToFD). During the trial Alternating Current Potential Drop (ACPD) was used to detect any growth as it occurred. Such techniques were used to substantiate claims AE could detect a propagating defect. When the AE is viewed in conjunction with ACPD results and the measurements attained with the ToFD it was clear that all three techniques concluded that crack growth occurred at two sites. Finally the investigation returns to a laboratory to exarnine the robustness of the technique through the life of a mechanical structure. The objective being to identify if periodical measurement of AE taken during the course of the life of the structure would repetitively generate information pertaining to the identification of the flaw as well as the severity of the flaw as it initiates and propagates through to failure. A power law was fitted to the data acquired during the proof tests. The use of a power law was considered appropriate due to the previously identified non-linear nature of material failure. A Scanning Electron Microscope was used to visually examine the fracture surfaces. It was found that increasing increments between striations on the fracture surface illustrated the non-linear increase of crack extensions during fatigue and corroborated the appropriateness of fitting a power law to the proof test data. Such an investigation permitted the conclusion that the approach of fitting a power law to the discrete energies from sequential proof tests is an appropriate method of attaining a trendable condition indicator. The competent person could employ such a methodology for the purposes of attaining information upon which an informed decision can be made on the continued safe use of mechanical structures

UXO Lao Detection Trial Test Report

During the period November 27, 2014 to December 20, 2014, UXO Lao undertook a detection trial in Sepon. The primary objective was to assess the suitability and cost effectiveness of advanced detection systems of small ordnance. Specifically, the trial was focused on detection of a half BLU-26 at 25cm depth below the natural surface (the national standard of the Lao People’s Democratic Republic (Lao PDR) as set by the National Regulatory Authority (NRA)). The Geneva International Centre for Humanitarian Demining (GICHD) along with Minerals and Metals Group, Lane Xang Minerals Limited (MMG LXML) and in cooperation with UXO Lao conducted and supported the detection trial. A numbers of advanced systems were compared with each other as well as with systems currently used in Lao, on blind test sites. Several digital systems performed well, with a number achieving a higher probability of detection and less than half of the false alarm indications compared to the successful analogue systems tested. As such, they certainly should be considered as viable UXO detection systems. Going forward, it will be important to develop accreditation, operational standards and QM processes for these systems. Some analogue systems did not perform as well as expected. The experienced technical staff handling the equipment may not have ensured proper calibration and handling of the detection equipment. Some of the results clearly highlights the importance of not only having trained staff but also a well defined quality management system that will ensure that staff and equipment is frequently tested, monitored and evaluated. Frequent refresher training is also another key component ensuring that staff is versatile with the equipment that they are using. This is even more important for supervisors that are not consistently operating the equipment

Preparing for the future: A reappraisal of archaeo-geophysical surveying on Irish National Road Schemes 2001-2010

yesThis document reviews Legacy Data generated from 10 years’ worth of road scheme activity in Ireland to determine how archaeological geophysical surveys could be carried out on national roads in the future. The geophysical surveys were carried out by several different contractors across a range of challenging field conditions, geologies, weather and seasons. The research is based upon the results of linear schemes but also has validity for wider approaches. The findings of this research are based upon the compilation of all terrestrial archaeological geophysical surveys carried out on behalf of the National Roads Authority (NRA), a review of the success or otherwise of those surveys in comparison with ground-observed excavations and in combination with experimental surveys that tested previously held assumptions or knowledge to determine best practice methods for the future. The use and success of geophysical surveys in Ireland differ quite significantly from those in the UK, from where many of the methods of assessment were derived or adapted. Many of these differences can be attributed to geology. Ireland has a very high percentage of Carboniferous limestone geology, overlain mostly by tills and frequent occurrences of peat. These soils can reduce, to some extent, the effectiveness of magnetometer surveys; the most frequently used geophysical technique in Ireland. However, magnetometer data can be maximised in these cases by increasing the spatial resolution to produce effective results. An increase in spatial resolution is also effective generally, for enhancing the chances of identifying archaeological features by discriminating between archaeological and geological anomalies as well as increasing anomaly definition and visualisation of small and subtle archaeological features. Seasonal tests have determined that Irish soils are generally suitable for year round earth resistance assessments although some counties in the southeast of the country may experience very dry soils at the surface during some periods of the year. A variety of sampling strategies were used in the past, however it is now apparent that detailed assessments across the full length and width of a proposed road corridor are the most appropriate form of geophysical investigation. Magnetometer surveys are generally suitable for most Irish soils and geologies, although exceptions apply in areas of near-surface igneous deposits, deep peat and alluvial soils; however magnetometer surveys are not capable of identifying all types of archaeological features and other methods will be required for a full evaluation. Analysis of the Legacy Data has determined that in general the NRA archaeological geophysical surveys were historically used in a very positive way on road schemes. The range of features assessed or identified account for most types of archaeological sites in Ireland. These have provided a significant archive of case studies that will be of benefit to future archaeological geophysical research and will help to protect the globally dwindling archaeological resource that is threatened by development-led or commercially driven projects

Archaeo-geophysical survey on the Ushpitun landform, Happy Valley-Goose Bay, Labrador

This thesis presents the results from a geophysical survey undertaken on the Ushpitun landform, an area of Intermediate period Amerindian occupation This archaeo-geophysical survey intends to test the efficacy of using magnetometry, ground penetrating radar, and magnetic susceptibility/conductivity to locate features on the landform. Additionally, the effectiveness and efficiency of geophysical survey methods will be compared to past non-geophysical methods. The results of this project conclude that magnetometry is the best means of locating features, though this is couched in the failure of the magnetic susceptibility/conductivity instrument and the inability of the ground penetrating radar to identify any near-surface features. Charcoal recovered from three combustion features was analyzed and calibrated radiocarbon dates offer a challenge to previous relative sea level dating in the area. An analysis of surface collected lithic materials supports Neilsen’s (2006) assertion that the landform was likely a limited procurement camp and not a long-term habitation site

Fatigue/fracture mechanics analysis of threaded tether connections

The use of threaded connections for joining tubes and pipes is widespread within the oil and gas drilling industry. Such connections have more recently been employed for the joining of tethering elements for a new generation of offshore platform, the Tension Leg Platform (TLP). The platform design depends totally on the integrity of the tethering system and the threaded connection between tether elements has been identified as a critical structural component. The hostile environment of the North Sea leads to severe cyclic loading on the tethering system and fatigue is the most likely in-service damage mechanism. This study involves an analysis of the fatigue behaviour of large threaded connections of the type proposed for tethering applications and considers the implications for subsequent in-service inspection and integrity assessment. A simplified model for the prediction of the non-uniform load distribution within the connection is proposed and this is validated using finite element (FE) modelling of a complete connection. A methodology for the use of this model, in conjunction with simple FE sub models, for the prediction of dynamic stresses in preloaded and unpreloaded connections is presented. Fatigue initiation and fracture mechanics based crack growth models are proposed for this application and large scale tests, to provide experimental data for validation of these models, have been conducted. An inspection system was developed to enable fatigue crack growth to be measured during the test. It is likely that this system will be suitable for integrity monitoring of large scale threaded connections removed from service. The requirements for integrity monitoring during service, based on a knowledge of the likely fatigue behaviour, are considered for a tethering system and a methodology for defining service inspection intervals as discussed

Electrical characterization of carbon nanotubes grown by the chemical vapor deposition method

Single-wall carbon nanotubes after a decade of research show fascinating properties with a promising prospective for possible applications. Their nanometer size and micrometer lengths make them an ideal material for research in nanotechnology. Contrary to most of the molecules, experiments in different scientific areas have been possible due to their robust, chemical inert characteristics (Chapter 1). We have successfully produced CNTs by CVD method. It has been shown that this method is well suited for the investigation of their electrical and mechanical properties. The main advantages of the CVD technique is that CNTs can be grown at specific location with flexibility to routinely implement them for different investigation purposes. Their electronic transport properties have been explored by fabricating the contacts by EBL or optical lithography in straightforward manner. In this thesis, investigation has been focused on CNT’s electronic transport properties from room to low temperature. Although their main characterization at room temperature (the gate dependance and high bias characteristics) does not depend dramatically on the contact resistance, low temperature measurement reveal the importance of the contact resistance and their correlation with the observed phenomena. We have found that problem of the contact resistance can be overcome by annealing of the devices contacted with Ti or using Pd as metallic electrodes on as grown CNT (Chapter 2). Ambipolar field-effect transistor action has been demonstrated on asgrown semiconducting SWNTs (Chapter 3). The observed ambipolar FETs can be tuned with a back-gate from p- to n-type conduction through the semiconducting gap. We have attributed high tunability of our devices to hydrogen presence during the CVD grow, which probably reduce trapped charges in a Si/SiO2 substrate, making coupling to the gate more effective. Electron and hole transport in the Coulomb blockade regime have been investigated in detail. A strong sensitivity on disorder has been observed in semiconducting SWNTs, which effectively brake the nanotube in small sections ≈ 40 nm forming multi-dot system. However, for sufficient doping i.e. by the gate voltage, localized states can be populated, where the transport occurs through an individual orbital. Moreover, doping of the tube section to higher subbands has been demonstrated. Detailed, two terminal transport measurements at low temperature have been performed on the metallic SWNT devices (Chapter 4). Spectroscopy on a SWNT QD can be performed by measuring the conductance as a function of the gate and bias voltages. For low transparent contacts, a SWNT behaves as a quantum dot where the transport phenomena are dominated by the single-electron charging effect (Coulomb blockade). For high transparent contacts, the four-fold degeneracy is observed with the Kondo effect. We have discussed several possible shell filling scenarios in SWNTs. In detail, the ground state of CNTs at half-filling, i.e. for N = 2 added electrons to one shell, is analyzed. We demonstrate that this state is either the singlet or a state for which the singlet and triplet are effectively degenerate, allowing in the latter case for the appearance of the Kondo effect at N = 2. For even higher transparency Fano resonances are observed. The origin of these resonances are identified as an interference between the resonant and non-resonant channels within a bundle of SWNTs. Finally, as grown CNTs have been suspended with three different methods to explore their mechanical properties (Chapter 5). We have shown that thermal vibrations are readily observed in SEM if the suspended length of a SWNT is sufficient (& 1 μm). Good agrement is found between thermal vibration derived for an elastic beam in continuum mechanics, with corresponding Young’s modulus in TPa range. However, for the SWNTs suspended by wet etching Young’s modulus seems to be smaller (� 20GPa). The possible interpretations are that wet etching severely damage CNT or that the boundary conditions are different than in the cases for the growth over predefined trenches and Si3N4 membranes. Our investigation showed that possible implementation of CNTs as nano-electromechanical resonators urges for careful design of the experiments with desirable control of their physical properties (diameter). In this thesis, we have demonstrated that transport investigation in CNTs show pronounced quantum effects with fascinating possibilities to explore the fundamental phenomena which has been elusive in other systems (S-QD-S, spin injection in low dimensional systems, Luttinger liquid, etc). In that respect, the exploration of CNTs opened a new chapter in material science and nanotechnology, as important milestone for the future investigation of molecular based devices