Professor Tripp Shenton, Chairman of the Department of Civil and Environmental Engineering at the University of Delaware, is a visionary when it comes to life-long monitoring of important civil structures. The Indian River Bridge that parallels Delware’s Atlantic beaches is an example of his vision being realized.

A new video details how strain, temperature, displacement, acceleration and other critical sensors became an integral part of this 2km long structure – and why Micron Optics’ fiber optic sensor technology was selected as means to deliver the needed measurements.

The University of Delaware, DelDOT, and Micron Optics’ integrators Cleveland Electric Labs and Chandler Monitoring Systems were among the key players that made the installation a success. If you’re considering SHM options for a civil structure project, or have an interest in fiber Bragg grating sensors for another application, this video is well worth a look.

Indian River Bridge on YouTube

6/26/2012 ETA – updated link to latest version of video

Orion is the Crew Exploration Vehicle that was created for NASA’s Constellation project. At first glance, Constellation is reminiscent of the Apollo system, with the crew riding atop a large launch vehicle. But Orion is meant for longer missions to the moon and rendezvous with asteroids. So while Apollo and Constellation might look similar, the engineering tasks represent a new set of challenges. See more here www.nasa.gov/

Fiber optic strain sensors are being used to verify the design and performance of a critical part of the Orion Capsule - the heat shield. Recent drop tests at the US Army’s Aberdeen Proving Grounds included 41 drops and various angles and velocities. A Micron Optics sm130-700 Optical Sensing Interrogator was the primary measurement tool gathering data from dozens of FBG strain gages welded to the interior surface of the heat shield.

Chris Lynn, NASA’s lead engineer for these tests, had this to say to the Micron Optics team following the tests “The Crew Module water landing drop tests were very successful, so much so that we completed a total of 41 drops when we only planned for 23 in the original test matrix. The fiber optic strain sensors provided by Micron Optics held up extremely well during testing - we didn’t lose a single sensor during the duration of testing. We greatly appreciate MOI’s support during all phases of work, without the great work the testing would not have been a success. Thanks again for the great work!”

Tom Graver
Vice President -Optical Sensing Group

Micron Optics produces the most reliable, capable and widely used FO instruments, sensors, and software in the world, but it’s our integrator partners who make so many successful applications possible. One good example is Sengenia, Ltd. in Northern Ireland. They’ve highlighted a recent application in their newsletter (see excerpt below) that involved embedding a network of FBG strain gages in a bridge deck and measuring them with a Micron Optics sm125 instrument.

These sensors were needed to evaluate the performance of a new “RockBar” reinforcement material for concrete decks. In quotes from the bridge owner, it was clear that Sengenia’s expertise and Micron Optics ENLIGHT software made the process of both installing the sensors and extracting and analyzing the data fast and simple.

Through their efforts, Sengenia has demonstrated to yet another group of engineers the power of fiber optic sensing technology. Successes like this one will lead to more applications, better methods, a greater variety of sensors, and a more widespread understanding for how FO sensors can enhance and improve upon traditional structural analysis and inspection practices.

For more information about Sengenia’s capabilities, and to subscribe to their newsletter, visit their website at http://www.sengenia.com.

Excerpted from Sengenia’s newsletter:
It is known that every year millions of pounds are spent, in the UK alone, on the repair and rehabilitation of concrete infrastructure. A large proportion of this is due to the corrosion of the reinforcing steel that is used and now with the introduction of fibre bars, such as those provided by MagmaTech , it is hoped that such financial waste can be prevented.

Thompson’s bridge is a replacement bridge to carry the two-way, A class road in Co. Fermanagh, Northern Ireland. The previous bridge was a pinch point and not suitable for the wide loaded vehicles that frequently use this stretch of road. The bridge is a single span, consisting of reinforced concrete abutments on piled foundations. The superstructure comprises of ‘W’ precast pre-stressed beams with a reinforced concrete slab bridge deck reinforced with RockBar.

Queen’s University Belfast (QUB), through Dr Su Taylor, were tasked with providing much of the specification details for the bridge and Sengenia worked alongside QUB for the load testing aspect of the project. Sengenia were able to use their fibre optic sensors, taking advantage of the ability to create more than one sensor along the length of a single strand of fibre, thereby reducing the cabling and therefore installation time and effort normally required. When used in tandem with the Micron Optics sm125-500 unit and Enlight software the monitoring process becomes a simplistic one, especially when taken in direct comparison with the alternative methods that were also in use through QUB.

Ben Williams, MD of MagmaTech commented ‘I was very interested to see the use of the fibre sensors actually in the field. The system used to acquire and display the data was remarkably simple to comprehend but yet clearly a highly sophisticated and powerful tool in such work. At MagmaTech we intend to pursue this further with Sengenia, looking always at how we can enhance the offering to our customers as well.’

Previously in this blog, and elsewhere, we’ve extolled the virtues of FBGs — like their small size, immunity to EMI, and resistance to corrosive environments.  In a recent paper in the Journal of Power Sources, Nigel A. David and a team from the University of Victoria, Canada have demonstrated the importance of each of these FBG sensor characteristics for their application.  David and his colleagues are interested in polymer electrolyte membrane fuel cells.  These are thin, flat structures that have an electrochemically active environment inside.  David et al detail how others have tried electrical and infrared optical techniques to characterize the performance of PEMs and how these methods come up short.  David concludes that using embedded FBG sensors “reliably measure[s] temperature dynamically with a relative resolution of less than 0.2 DEG C,” and is an inexpensive approach that may prove useful for understanding current distribution across the PEM cell.

FBG measurements in this study involved both Micron Optics instrumentation and sensors, specifically the sm130 Optical Sensor Interrogator and os1100 FBGs.  See the full paper at: Science Direct