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

Visual Transfer Learning: Informal Introduction and Literature Overview

Transfer learning techniques are important to handle small training sets and to allow for quick generalization even from only a few examples. The following paper is the introduction as well as the literature overview part of my thesis related to the topic of transfer learning for visual recognition problems.Comment: part of my PhD thesi

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

Aplicação do ensaio de emissão acústica à inspecção de cabos de aço

Trabalho final de mestrado para obtenção do grau de Mestre em Engenharia Mecânica – Ramo ProduçãoNos recentes anos, a presença dos ensaios não destrutivos na indústria tem-se revelado como essencial para o envolvimento da qualidade na produção e na manutenção dos mais diversos equipamentos. Entre o vasto espectro de ensaios não destrutivos, este trabalho destaca a aplicação do ensaio de emissão acústica na inspeção de cabos de aço, um dos elementos de transmissão mecânica mais importantes atualmente. Este trabalho inicia-se por uma revisão teórica sobre cabos de aço, ensaios não destrutivos, o ensaio de emissão acústica e o estado da arte da aplicação desta técnica aos cabos de aço. Com base nesta revisão, são realizados dois ensaios experimentais, nomeadamente a análise do comportamento acústico de um cabo sob tração e a determinação da localização de fissuras através do software de processamento de sinal.In recent years, nondestructive testing presence in industry has been revealed as essential for quality involvement in production and maintenance of several equipment’s. Between the diverse spectrum of nondestructive testing, this work highlights the acoustic emission testing application in wire rope inspection, one of the most important transmission elements today. This work initiates with a theoretical review of wire ropes, nondestructive testing, acoustic emission testing and a state of the art of this technique applied in wire rope inspection. Based in this review, two experimental tests were conducted namely the acoustic behavior analysis of a wire rope subjected to tensile stress and the second test was the location of cracks via a signal processing software.N/

The 24th Aerospace Mechanisms Symposium

The proceedings of the symposium are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, latches, connectors, and other mechanisms for large space structures

Pioneer Venus

Venus before Pioneer, the Pioneer Venus mission, Pioneer Venus spacecraft, scientific investigation, mission to Venus scientific results, and results of Soviet studies of Venus are addressed. A chronology of exploration of Venus from Earth before the Pioneer Venus mission and Venus nomenclature and mythology are provided

JUNO Conceptual Design Report

The Jiangmen Underground Neutrino Observatory (JUNO) is proposed to determine the neutrino mass hierarchy using an underground liquid scintillator detector. It is located 53 km away from both Yangjiang and Taishan Nuclear Power Plants in Guangdong, China. The experimental hall, spanning more than 50 meters, is under a granite mountain of over 700 m overburden. Within six years of running, the detection of reactor antineutrinos can resolve the neutrino mass hierarchy at a confidence level of 3-4$\sigma$, and determine neutrino oscillation parameters $\sin^2\theta_{12}$, $\Delta m^2_{21}$, and $|\Delta m^2_{ee}|$ to an accuracy of better than 1%. The JUNO detector can be also used to study terrestrial and extra-terrestrial neutrinos and new physics beyond the Standard Model. The central detector contains 20,000 tons liquid scintillator with an acrylic sphere of 35 m in diameter. $\sim$17,000 508-mm diameter PMTs with high quantum efficiency provide $\sim$75% optical coverage. The current choice of the liquid scintillator is: linear alkyl benzene (LAB) as the solvent, plus PPO as the scintillation fluor and a wavelength-shifter (Bis-MSB). The number of detected photoelectrons per MeV is larger than 1,100 and the energy resolution is expected to be 3% at 1 MeV. The calibration system is designed to deploy multiple sources to cover the entire energy range of reactor antineutrinos, and to achieve a full-volume position coverage inside the detector. The veto system is used for muon detection, muon induced background study and reduction. It consists of a Water Cherenkov detector and a Top Tracker system. The readout system, the detector control system and the offline system insure efficient and stable data acquisition and processing.Comment: 328 pages, 211 figure

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