SIMoNET Seminar , May 2002

Report on the SIMoNET seminar, 22nd May 2002 at UCL NDE Centre.
by Prof Bill Dover

Introduction

Professor Bill Dover as the Chairman welcomed the participants and gave a brief update on SIMoNET highlighting the strong industry feedback for the initiative which is much appreciated. He went on to say that this is the first industry sponsored seminar in phase II intended to facilitate information exchange amongst the attendees from the industry, SMEs and technology providers and universities.

Nine papers were presented at the seminar and a brief outline and key points of each presentation follows:

Continuous Structural Integrity Monitoring of Offshore Structural Nodes, John O'Brien, Physical Acoustics Ltd

An overview of Acoustic Emission (AE) in providing continuous monitoring of fatigue damage in structural members (e.g. offshore welded nodes) was provided. Types of equipment, software and remote interfaces for accurate monitoring, discrimination of events and swift data processing were presented, based on work at Cardiff University. This is achieved through detecting and locating active emissions and discrimination is feasible to discard emissions due to crack rubbing. A particular application for offshore structures and nodes as an aid to ensuring structural integrity is proving effective enabling a focus on critical areas and nodes. Some trials had been undertaken on a box girder bridge over the M6 motorway and on an offshore floating installation. Cost effective reporting had been achieved via a secure automated web site.

Cost Effective Structural Monitoring: an Acoustic Method, Mark Harper, Mecon Ltd

This presentation outlined the development of a practical use of AE in continuous monitoring of multiply connected structures, such as North Sea offshore installations. It was based on data generated on a plastic wire frame model at a scale of 1:100, simulating a jacket structure by fixing transmitters and receivers to monitor acoustic functions to detect and locate changes in acoustic response. The conclusions were that AE is applicable to such complex structures. This is achieved through a modified time step method to model and characterise transmissions, hence allowing damage location to b ahieved. Locating the transmitters above water line was considered key in obtaining cost effective and realistic data. Further work was planned both using the technique on the existing model and also on a steel structure

National & European Networks on Structural Integrity, Prof. J.V. Sharp, Cranfield University

Professor Sharp outlined the basis for the growing number of networks associated with structural integrity. These included networks funded initially by the Engineering & Sciences Research Council, including Simonet and the related networks (Asranet, Sidanet), as well as OWEN (Offshore wind energy network). All of these were now moving into a second phase, with industry or other funding. European thematic networks were becoming well established, with several (SAFERELNET, TRENDS, SAMCO) having links to structural integrity. In addition there were another 11 specialised networks focussing on specific aspects of materials, corrosion or particular structural elements. SAMCO (Structural assessment, monitoring and control) started in 2001, led by the JRC for structural assessment, with BRE and TRL Ltd as the lead UK partners. Its main interests are associated with monitoring bridges, roads etc. Professor Sharp outlined the main aspects of the Sixth European Framework programme, which was focussing on establishing a European Research Area. Networks of excellence were also to be part of this .In conclusion he said that networks were growing in number, covering a wide range of interests and provided an opportunity for linking with other partners, dissemination of research interests to industry and developing future research proposals.

ACFM in the rail industry - Mark Howitt, Condition Monitoring, Bombardier Transportation Services

Mark Howitt outlined the many inspection jobs that take place in the rail industry - both on vehicles and infrastructure - and listed the inspection techniques used at present. He then described the ACFM technique and outlined the advantages this technique had, particularly compared to MPI. Bombardier Transportation have pioneered development of ACFM for the rail industry, particularly for inspection of bogies, where new water-based paints are very difficult to remove. Mark also presented results from independent trials of ACFM and MPI on axles, in which ACFM was found to be significantly better. Finally, Mark also described a new development of ACFM for detection of gauge corner cracking on rails.

Monitoring with ACFM - Martin Lugg, TSC Ltd

Martin Lugg outlined how ACFM had originally developed to replace ACPD for underwater crack sizing, and then listed the advantages the technique had for inspection. ACFM is now able to provide many benefits in crack growth monitoring, the main preserve of ACPD. Martin listed the advantages and disadvantages of ACFM and ACPD for monitoring and gave examples of results obtained for both techniques. Finally, two potential future applications for ACFM monitoring were described - monitoring existing cracks underwater during the winter, and remote monitoring of unmanned installations.

Integration of NDT Approaches throughout a product life cycle using Moiré, Professor Eann Paterson, Sheffield University

Professor Paterson described how new developments in using polarised light to provide valuable information on stress analysis. A method had been developed for shape correction in photoelasticity in the reflective mode. This enabled 3D objects, such as large compressor blades to be analysed. Comparison with CAD models was also possible, enabling the technique to be used both in design, manufacture and in-service maintenance. Examples were show of the application of the technique in practice.

Fatigue & fracture of tubulars containing large defects, Bijan Talai-Faz, UCL NDE Centre

Bijan Talai-Faz described the full scale strength tests that had been completed on joints representative of a jack-up platform, containing large cracks. Photogrammetry had been used, with specific reflective targets fixed to the specimen. The use of two cameras set at about 2m away from the specimen allowed deformations to be detected at each load increment, with an accuracy of +/- 0.5mm. There were advantages in the technique being non-contacting. Examples were shown of the initial crack opening and at a later crack tearing stage. He saw future possibilities for the technique in monitoring buildings, or with cameras on satellites using lasers as targets.

Use of Guided Ultrasonic waves to inspect tendons in concrete and rock bolts in mines, Dr. Malcolm Beard, Imperial College, London

Dr. Beard explained that inspection methods for rock bolts in the roof of coal mines are limited. The use of transducers clamped onto the free end of the bolt provided information on the length of the bolt from the reflected signal and hence able to detect breakages. Different test frequencies had been tried, with different attenuation levels and properties found for both the high and low frequency methods examined. Trials of the method had been undertaken in a limestone mine and the method was now being developed by a mining company .

A similar technique had been used for examining tendons in post tensioned concrete structures. These tendons are in grout filled ducts. However due to high attenuation of the signal detection of any breakages was limited to a range of ~1m from the transducer..

Proposed Development of a National NDE Centre with EPSRC funding, Dr. Fergal Brennan, UCL NDE Centre

Dr. Brennan described this application, bringing together key researchers from several UK institutions to conduct long-term multi-disciplinary research within a multi-institution centre. The National NDE Centre aims to promote the safety of systems through the integration of structures and materials understanding, advanced sensors and modelling. The core academic collaborators are UCL, the Universities of Sheffield, Warwick, Cambridge, South Bank, Surrey and Loughborough. The plan is that the Centre will be managed by a dedicated manager from TWI.

Closure, Professor Bill Dover, UCL NDE Centre

Professor Dover outlined the plans for phase II of Simonet, with industrial funding (based on a fee of £600 p.a.). At this stage at least 10 organisations had agreed to join but other Sponsors would be welcome. Future seminar would be held on relevant topics and the web site would be developed further. He thanked the speakers and those attending for their contributions.

seminars index