Metallurgical Consulting Services Ltd. has been selected as the winner of an ASM Canada Council John Convey Innovation award for 2012.
The ASM Canada Council John Convey Innovation Awards were established in 1997 to recognize companies for their contributions to furthering the development of the Materials Engineering Industry in Canada. The awards consider achievements and/or service directed at the Canadian or international marketplace.
The citation for Metallurgical Consulting Services Ltd. reads:
"For advancing knowledge of metallurgical science and practice, and for innovative contributions to the safety and continued safe operation of industrial plants and equipment through knowledge of failure mechanisms, evaluation of damage and methods of remediation."
A plaque commemorating this award will be presented to Dr Iain Le May, President of Metallurgical Consulting Services Ltd., at MS&T'12 in Pittsburgh, USA, in October.
Closing date for Nominations: 14 September 2012, 17:00 GMT
The £1million QEPrize has been established to reward the individual (or up to three individuals) responsible for an engineering-led advance that has been of global tangible benefit to humanity.
The first-ever prize will be awarded by Her Majesty, the Queen, in Spring, 2013.
For further information, see the QEPrize website at http://qeprize.org
The 8th meeting of the ESIS TC2 technical committee on Micromechanisms was held at Mansfield College, Oxford University, UK on 2nd-3rd April 2012, in collaboration with the UK Forum for Engineering Structural Integrity (FESI). Over 50 delegates attended: from the UK, Czech Republic, Austria, Slovenia, Germany, France and the Netherlands, with 9 delegates partially supported by ESIS bursaries for young scientists. The organising chairs were James Marrow (University of Oxford) and Jaroslav Pokluda (Brno University of Technology). There were 24 oral presentations and a poster session with over 10 contributions. The meeting sessions, spread over the two days in a continuous programme, were: Microstructure and Plasticity; Fatigue; Fracture and Constraint; and Ceramics and Composites, and were chaired by Jaroslav Pokluda, Peter Flewitt (University of Bristol), Alan Cocks (University of Oxford), David Smith (University of Bristol) and James Marrow.
Photo: Petr SestŠk (Brno University of Technology).
The topics discussed covered a broad range, with some common themes addressed by several presentations: these included; modelling and measurement of critical shear stress for plastic deformation; the heterogeneous deformation of polycrystalline grain assemblages responsible for intergranular cracking; the role of constraint and residual stresses on crack tip deformation in fatigue; the influence of microstructural evolution on damage mechanisms and fracture property modelling of heterogeneous microstructures.
The delegates enjoyed a walking tour of Oxford's historical architecture prior to the meeting, and a very convivial candle-lit dinner in the oak-panelled Mansfield College hall; a number of international collaborations may have been sparked off by the event. A special issue of the ESIS affiliated journal, Engineering Fracture Mechanics, is planned for publication in 2013, and will contain papers from the meeting. A delegate list, extended abstracts of all contributions, copies of the majority of the presentations and some photographs of the event are available from the meeting website (energy.materials.ox.ac.uk/Meetings/esis-tc2-oxford.html).
Thanks to all those who contributed to a very successful and enjoyable meeting.
The section of Hammersmith flyover that hit the headlines with its closure over Christmas 2011 is of a segmented post tensioned construction. All of the elevated sections of the M4 from Chiswick to Hammersmith have been under continuous investigation, repair and maintenance for the past 20 years or more. However, most of it is of conventional reinforced concrete and easier to investigate, monitor and repair than the prestressed sections. The problem is the intrusion of deicing salts into the concrete. The chloride ions diffuse into the concrete cover and compete with the hydroxyl ions at the steel surface that sustain the protective passive oxide film. When the chlorides exceed a critical threshold level the passive oxide layer formed in the alkaline hydroxide environment breaks down and corrosion of the steel ensues.
For conventional reinforcement, the results can appear dramatic as a mere 50 microns of reinforcing steel section loss can create sufficient corrosion product to crack and spall the concrete cover to the steel. If you drive under the M4 elevated sections in certain areas you can see exposed reinforcement where loose cover has been removed to avoid the risk of damage and injury, as shown in Figure 1 taken a few years ago. However, for these reinforced concrete sections, the loss of a few tens of microns in steel section is very unlikely to cause structural problems.
Figure 1 - exposed reinforcement on cross beams under the M4 elevated section
due to deicing salt leakage through the expansion joints onto the substructure.
Impressed current cathodic protection is now being installed in conventionally reinforced elevated sections of the M4 to control the corrosion and is routinely applied to conventionally reinforced concrete bridges and other structures suffering from reinforcement corrosion, see Concrete Society Technical Report 73, "Cathodic Protection of Steel in Concrete" 2011. As conventional reinforcing steel is embedded directly into the concrete we have physical, chemical, electrochemical, electromagnetic and acoustic methods that can be used to assess the corrosion and the condition of the structure. For instance, simple hammer sounding will identify delaminations of the concrete before they become spalls. Half-cell or reference electrode potential mapping will identify areas of high corrosion risk. Progressive chloride drillings will determine the rate of progression of chlorides into the concrete cover and the level at the reinforcement.
The regular condition assessment and rating of highway structures is mandated by the Highways Agency. Although the Hammersmith Flyover is now under the jurisdiction of Transport for London, this has been done throughout its life and gave warnings that all was not well. These assessments are now done on a risk assessment basis and the Hammersmith flyover would have been recognised as a high risk structure.
On these bonded post-tensioned structures, the issues are rather different from conventionally reinforced structures. In this case the prestressing wires run through ducts and are stressed up to 80% of the wire's ultimate tensile strength at the time of construction. They are then filled with a cementitious grout to bond the tendons to the duct and to provide corrosion protection. If chlorides get into the ducts and the cementitious grouting is inadequate then corrosion can proceed rapidly and the consequences can be more structurally significant and are harder to monitor and assess than for conventional reinforcement. Most of our assessment techniques will not work through the tendon ducts so the assessment is often of the integrity of the ducts and the anchorages or by physically breaking out the tendons for examination of the steel condition and the quality and effectiveness of the cementitious grout. Also techniques corrosion control techniques such as cathodic protection are difficult to apply as they too cannot work through the ducts and there are risks of hydrogen embrittlement of the strands which could exacerbate rather than ameliorate the problems.
I understand that the prestressed section of the Hammersmith Flyover had been fitted with a state-of-the-art acoustic monitoring system. This and other Structural Health Monitoring systems are discussed in the recent CIRIA report No. 661 on "Intelligent monitoring of concrete structures" published in 2008. The acoustic emission system is tuned to detect the "ping" of prestressing strands failing as the loss of steel section due to corrosion means the strands can no longer bear the prestressing load. This, along with physical inspection of tendons which found corrosion in unexpected areas at the top of the deck segments, led to the decision by the structural engineers to close the bridge until they could be certain that it was capable of accepting the loads without the risk of failure.
Post tensioned concrete bridges have been a long term problem to the civil engineering and corrosion engineering community for many years. In the mid 1990s, after several failures that were not foreseen, the Highways Agency applied a moratorium on the construction of post tensioned bridges in the UK until new design codes gave better confidence that the post tensioned cables could be protected from chloride ingress and corrosion of the strands (Concrete Society Technical Report 47, 2002). However, Hammersmith and many other bridges date from before that time and do not have the level of protection used in current designs.
Even relatively new post tensioned bridges have been found to have problems. Florida Department of Transportation have found that due to the natural shrinkage of the grout and the formation of bleed water at the surface, the tendons can be left completely unprotected. In a marine exposure condition this has led to severe corrosion of anchorages and massive retrofitting of post-tensioning to structural columns in the sea. (Sagues, A. A., et al. (2005). "Corrosion of the Strand - Anchorage System in Post- Tensioned Grouted Assemblies." NACE Corrosion Conference, Houston USA, Paper No. 05266).
It can therefore be seen that the corrosion of post tensioned highway structures in high chloride conditions is well understood by scientists and engineers. However, it is very difficult to assess and monitor on post tensioned structures in the field due to their design. Despite improvements to the corrosion protection systems of the post tensioned strands, we are still finding problems on relatively new bridges as well as the older ones like Hammersmith that were built before the problems were identified in the 1990s. Structural health monitoring systems can be built into new structures, but that rarely happens. They can also be retrofitted into existing structures and that has happened at Hammersmith. This helped give the warning that more detailed investigation was needed and now the structural engineers and contractors are designing new post tensioning to be installed in the flyover to restore its full load capacity.
John Broomfield is a consulting engineer specialising in the corrosion of steel in concrete and corrosion of the built environment. His book "Corrosion of steel in concrete; understanding, investigation and repair" is in its 2nd edition and is published by Taylor and Francis UK. Broomfield Consultants, www.jpbroomfield.co.uk.
FESI is delighted to welcome Det Norske Veritas (DNV), a leading international provider of services for the management of risk, and an independent foundation with the purpose of safeguarding life, property, and the environment.
Established first in Norway in 1864 to inspect and evaluate the technical condition of Norwegian merchant vessels, and working internationally since 1867, DNV's core competence has been to identify, assess, and advise on how to manage risk, and safely and responsibly improve business performance. DNV's Corporate Vision, Global impact for a safe and sustainable future, is complemented by an internal business culture into which Corporate Responsibility is fully integrated.
Headquartered in Oslo, Norway, DNV is a knowledge-based company with approximately 300 offices in 100 countries, and 9,000 employees from more than 85 different nations.
While many of DNV's services such as management system certification and corporate responsibility can be applied successfully in any industry, their main focus is on the Maritime, Oil, Gas & Energy, Food & Beverage and Health Care industries.
Further information on DNV's services, research and innovation, current projects and news may be found at www.dnv.co.uk.
This publication presents an analysis of strength and fracture criteria. The author offers a new, more precise, evaluative theoretical decision procedure in regard to mechanical behaviour of materials and structures, which is proven through experiments. It shows the necessity to evaluate the mechanical behaviour of materials and structures in cases of a complicated state of stress and different anisotropicity. This new criteria of strength and fracture evaluation should be applied during the creation of new materials, structures and technologies.
This book is intended for the scientists of mechanics and construction engineering, together with graduate students and engineering staff.
An essential new specialist handbook for fracture toughness estimation in structural integrity assessments
"... valuable and up-to-date... fresh insights and a wealth of data"
Order from EMAS.
Fracture Toughness of Engineering Materials - Estimation and Application, Professor K R W Wallin's authoritative guide and practical handbook on fracture mechanics in the context of Engineering Structural Integrity Assessment (ESIA), is released by EMAS Publishing, the publishing arm and online bookshop for FESI, the UK Forum for Engineering Structural Integrity.
This `rule-of-thumb' reference work will increase existing knowledge, encourage avoidance of commonly held but potentially dangerous misconceptions, and stimulate new, improved applications that will help fracture mechanics to develop further. The clear insight into the underpinning of physical concepts combined with experimental data and case studies, the vast majority of which are new and previously unpublished, will complement fracture mechanics textbooks and courses.
Fracture Toughness of Engineering Materials - Estimation and Application has four main themes:
Kim Wallin is a renowned international expert in the field of fracture mechanics and was major contributor to the development of ASTM Standard of the Master Curve Method, E1921.
Fracture Toughness of Engineering Materials - Estimation and Application draws on his lifelong passion for fracture mechanics and explains some of the engineering puzzles he has encountered to date during his 30+ year career.
This authoritative guide and practical handbook for advanced students, fracture mechanics practitioners and R&D specialists is OUT NOW and available to order from EMAS Publishing, FESI's online bookshop and publisher.
Two more awarding-winning, innovative and world-class Corporate Sponsors join FESI:
Design Unit, University of Newcastle
Department of Design, Development, Environment and Materials (DDEM), Open University
FESI is delighted to announce that the University of Newcastle's Design Unit and the Department of Design, Development, Environment and Materials (DDEM) at the Open University will be supporting FESI's critical working to assure the reliability, safety and economic viability of engineered systems, structures and components from design to end-of-life, whilst minimising undesirable environmental impact. Both departments, in common with FESI, promote strong links between academia and industry to meet the UK's future engineering safety needs.
The University of Newcastle's Design Unit is a specialist gear technology outreach centre for Mechanical Power Transmission Systems, based in dedicated facilities within the award-winning School of Mechanical and Systems Engineering at Newcastle University. Specialising in gearing consultancy and research, Design Unit provides gear design, performance testing, gear metrology, and failure analysis services to the international gearing industry, including the automotive, aerospace and defence sectors.
DDEM is based within the Open University's Mathematics, Computing and Technology Faculty. Formed in 2007, DDEM brings together groups with a long history of innovation in teaching and research including the Environmental and Mechanical Engineering Group, Design Group, Development Policy and Practice Group, Materials Engineering Group, and Sustainable Technologies Research Group. DDEM's core research themes focus on fabrication, residual stress analysis and high temperature performance of metals and structures.