NEWSLETTER

Structural Integrity Monitoring is an established practice but recent developments could make it much more widely used. It is deemed to be necessary, as with periodic inspection, because of the fact that structures, although designed to survive in service for a prescribed design life, may fail prematurely. This is often due to environmental, manufacturing, material and design uncertainties exceeding the safety factor allowed for in the original design strength. The net result is that structural strength may degrade to a point where failure becomes possible earlier than anticipated. Failure of structures may cause loss of life, environmental damage and it could be very costly.

It is for these reasons that in-service inspection is conducted, and this is usually periodic. However periodic inspection, in many cases, can only be done during shutdowns or by restricting normal operations. Recently it has been realised that structural integrity monitoring offers an alternative and in some cases far more beneficial alternative to periodic inspection as it avoids interrupting normal operations, can interface with remaining life software giving instantaneous updates on structural integrity, and can be more accurate. The advances in information technology have made the possible widespread use of SIM a much more practical solution.

The information required from monitoring is many and varied. It could be that information on service stresses, material changes, loss of section, distortion, defect initiation, crack growth etc, are needed. Thus a wide variety of sensors are needed and traditionally these have varied from, say, simple visual inspection up to the more sophisticated ultrasonics or electromagnetic techniques. Traditional methods of structural monitoring include strain gauges and displacement sensors or accelerometers. Data retrieval from these systems has been a problem but new technological developments are now making it possible to monitor continuously the state of a structure, remotely. In principle, this allows the responsible person to interrogate a structure to determine its current condition. This would then allow the estimation of the probability of failure and remedial action if necessary.

Structural monitoring can, in essence, be regarded as a three part system including a Sensor, a Data Retrieval System, and Interpretation. At present each method has been developed independently by its own manufacturer. Retrieval, interpretation, data storage and analysis could be common to all techniques and this would facilitate greater commonality and cost savings in future installations. It could also provide greater safety by removing common errors and there is a further possibility of data fusion leading to better quality information in critical situations. The final step would be to move towards International Standards and this has already started. For all of these reasons the SIMoNET project was proposed and funded by EPSRC.

SIMoNET has been established with a broadly based committee membership including HSE, AEAT, Railtrack, Ove ARUP, BP-Amoco, Fugro, BMT, Atkins, and various Consultants It is run by UCL and Cranfield University with a web site www.simonet.org If you are interested in being involved in SIMoNET please contact either Mike Lock (m.w.lock@cranfield.ac.uk), John Sharp (J.V.Sharp@btinternet.com) or Bill Dover (wddover@btinternet.com) in the first instance.

SIMoNET is establishing a multidisciplinary group for the exchange of information and experience on SIM. It is linking Industry and University in order to solve problems of common interest and exchange information on SIM. SIMoNET has begun to identify the latest available technology, experience in use and methods of retrieving and interpreting data. It is working within the UK to encourage the harmonisation of data storage and retrieval by identifying incompatibility within systems. SIMoNET will be attempting to provide general guidelines for the practice and application of structural monitoring and to identify priorities for further development. As part of this activity a newsletter will be produced every 3-4 months. Articles for this newsletter (500-1000 words) will be welcome from all members.

SIMoNET will be attempting to become an international network in the future using additional EPSRC funding. The proposal has been submitted and the status will be reported in the next issue of the newsletter.