Work is nearing completion at the new Indian River Inlet Bridge at Rehoboth Beach, Delaware.  In the next few months the bridge construction will be completed and the embedded fiber optic structural health monitoring system will come on line.  Tying together fiber optic based sensors that monitor strain, acceleration, tilt, chloride penetration and movement at key locations, this system will help the Delaware Department of Transportation see the real time performance of the bridge over time as well as during significant events such as hurricanes or earthquakes, which the bridge site recently experienced both of in a two week period. 

Due to the inherent immunities to environmental damage offered by fiber optics, this embedded system will be functional for years to come and the long term data gathered will give DelDOT bridge engineers valuable information on how the bridge functions on a daily basis, seasonal patterns and as it will aid in future determination of maintenance needs. 

The optical monitoring system wall act as an early warning system that provides real time continuous data during significant events that may require the bridge be closed to traffic for safety reasons.  It will be one of the first systems of its type on a new construction bridge in the United States and will provide a model for how this type of system can be integrated into new construction projects to give a level of knowledge to engineers not previously possible.

Please visit the fiber optics page of our website and follow the link to structural health monitoring for more information.

Almost any sized fastener can be converted to BrainyBolt so please contact CEL to learn about this exciting fiber optic sensing technology.

The Indian River Inlet Bridge monitoring system is one of several projects in the US that will show how fiber optic structural health monitoring can become an integral part of evaluating and maintaining critical structures over time.  Immunity to environmental interference, nearly limitless system distance, multiplexed sensors and high speed simultaneous data sensing make fiber optic sensors the idea choice for long term structural health monitoring.

Also important, turbine engine fiber optics sensors and sensing systems can relay data to an interrogator hundreds of times faster than traditional sensors. Transient temperatures, melt points, and indications of surge must be sensed in fractions of seconds to give test engineers time to react and correct undesirable turbine engine conditions and perhaps time to prevent catastrophic events 

1. Public Safety- fiber optics are used to “see inside the structure” where the human eye cannot see to identify the slightest structural changes that could, over time,  become dangerous
2. Asset Management- this 150 million dollar asset must be protected.  An expansion joint is intended to move, but when frozen, may cause damage to adjacent bridge members.
3. Condition Alarms-fiber optic sensors are used to signal conditions during extreme events, high winds, extreme temperatures, overloading
4. Data Collection- data collected will expand fundamentally the knowledge of bridge behavior
5. Construction Aid- sensors embedded in pylons, decks, and installed on selected cable stays enhance the precision of the process

“Everyone has heard about bridge failures in the past including the Tacoma Narrows Bridge, Silver River Bridge and the I-35 Bridge in Minneapolis,” says Dennis Mertz, Director of UD’s Center for Innovative Bridge Engineering.

Cleveland Electric Labs of Twinsburg ,Ohio was awarded the contract for fiber optic sensors and sensing systems for  the Indian River Inlet Bridge.

FBG fiber optics sensors are being embedded into flooring and terminal mats and into buried cable by application engineers at Cleveland Electric Labs. The sensors are fiber optic strain gages that respond to the slightest pressure change when an unexpected intruder’s weight or unwanted mass is placed on it. As soon as the Cleveland Electric Labs FORRmat (fiber optic rapid response mat) , or FORRguard (direct burial cable) FBG sensors are deflected,  the FBG sensors reflect light waves back to a scanner that results in an immediate recognition of the intrusion location.  In most instances, the deflection sends a signal to a hidden video camera at the site that is programmed to tape the intrusion instantaneously when the signal is sent from the FBG sensor.

Fiber optic intrusion detection will become the security standard because is it immune to high and low temperatures, harsh chemicals and corrosion, lightning strikes, and radio frequency and electromagnetic interference.

A Laser/interrogator sends light waves through a glass fiber cable.  FBG sensors strategically located and embedded in the fiber cable reflect portions of the light back to the interrogator. The interrogator scans the light waves reflected back from the FBG sensors.  The waves scanned from each sensor are converted to numerical data for each location.

Fiber optic applications at Cleveland Electric Labs Advanced Technologies Group include fiber optic sensors to identify; new higher temperature capacities for turbine engines, the structural integrity of bridges, the imminent failure of structural fasteners (bolts), the means to identify terrorists and intruders, and impact of flight conditions in aircraft.

Fiber optic sensors are being specified versus electronic sensors developed in the 1950’s. All or some of the fiber optic applications noted below require these fiber optics advantages — immunity to EMI, RFI, corrosion, chemicals, high heat or very cold conditions. Fiber is easily routed in tight places, and is very light weight. Fiber optic sensors respond hundreds of time faster than electronic sensors and one fiber trunk line can transmit data from 80 sensors. Electronic sensors require individual connections for each sensor creating a weight concern in addition to the labor that is required.

High Temperature Fiber Optic Applications

Fuel consumption and performance are two critical cost factors for turbine aircraft operators. Every ounce of fuel consumed by either a commercial or military aircraft engine increases operating cost.  Jet engines that run hotter are often more efficient because they develop more horsepower and thrust.  Fiber optic sensors and interrogators are needed for engine testing because traditional thermocouples, normally used to measure engine heat, cannot respond in fractions of seconds. During engine testing transient temperatures, engine material melt points, and indications of engine surge require instantaneous temperature measurements to avert undesirable conditions and potential catastrophic events. CEL Advanced Technologies Group engineers have developed fiber optic sensors that can withstand sustained temperatures of 1400C, the first high temperature fiber optic sensors ever developed for commercial use

Structural Health Monitoring Fiber Optic Applications

70,000 bridges in the US have been determined “structurally deficient” by the American Association of State Highway Traffic Officials. These and other bridges require frequent inspections, maintenance, and repair.  Bridges have been visually inspected for over 80 years and recently ultrasound and electronic devices have been used. However, each inspection method has specific drawbacks and we believe no inspection and monitoring technology can equal the benefits of fiber optics. CELs engineers fiber optic applications that include structural health monitoring plans utilizing fiber optic strain gages, fiber optic temperature gages, fiber optic scour gages, fiber optic tilt and vibration sensors. The sensitivity of fiber optics sensors enable slight changes in aging bridge structures to be evaluated and monitored effectively. Fiber optic sensors and sensor arrays are mounted on a bridge and connected to a fiber optic trunk line. Up to 80 sensors (of different types) can be connected to one fiber and connected to one channel of an interrogator. The interrogation instrument can operated by solar power if no electricity is present. The data gathered is analyzed by a computer and be accessed at the bridge location or transmitted by satellite to a remote monitoring station. Each sensor on the structure can be identified by its individual address on the bridge and each sensor reports its condition– temperature, vibration, strain, tilt etc.

CEL Advanced Technologies Group can provide both the monitoring strategy and provide the fiber optic applications plan plus complete the bridge installation. Various supply companies can provide some of the ingredients required for SHM, but CEL can supply all the requirements; monitoring plan, sensors and interrogation equipment, installation, on-going monitoring and data analysis.

Fiber Optic Applications-Security

Perimeter security is a critical concern for all high value public facilities and private locations. Nuclear power plants, water treatment facilities, and electric utility substations, and other targets need to be protected from intruders. Locations that rely upon fences and video surveillance are frequently violated. Utilities substations are attacked every day and trespassers are being electrocuted as they attempt to steal copper parts from generating and transmission equipment. Lawsuits against utilities are commonplace.

CEL Advanced Technologies Group has fiber optic applications that include buried security cable. The fiber optic cable is so sensitive that when a trespasser steps within 5 feet of either side of the buried cable, the trespassers exact location is registered instantaneously signaling the sub-station monitoring personnel that may be many miles from the substation. Even more important for law enforcement officials, a video camera (that can be concealed from view many yards away) can be trained to immediately focus on the exact location of the violation. The exact intrusion location creates a high probability that the camera can capture the identity of the perpetrator.

Another security product FORRmat, fiber optic rapid response mat,  from the CEL Advanced Technologies Group detects illegal entry in locations that use card swiping devices for legal entry. This important fiber optic application is designed to identify “tailgaters,” trespassers without legal swipe-cards. Tailgaters enter a secure facility close behind a legal card holder either by force or by not being noticed by the legal card holder as he or she enters the “secure” facility.  FORRmat, the fiber optic rapid response mat from Cleveland Electric Labs detects tailgating. Fiber optic sensors embedded in this non-descript entry mat are sensitive to multiple weight points that simultaneously compress the sensors. The mat can detect the weight of two persons or four footprints where the weight of only one person or two footprints should be sensed. The FORRmat fiber optic sensors signal a violation and in an instant a video camera aims at and records the incident. Sensors notify security personnel of an unlawful intrusion.

A long series of FORRmats, manufactured similar to the above fiber optic application is capable of detecting transit station encroachment. Across the world transit authorities are threatened by persons who attempt suicide by jumping in front of oncoming trains, or attempt to de-rail trains by placing explosives on tracks. The FORRmats fiber optic sensors, and the  accompanying interrogation system, immediately detects transit violations and trains a video camera on the track at the exact location of the violation to alert authorities of an impending catastrophe.

Fiber optic Applications-Structural Fasteners-Bolts with Brains

Each year thousands of bolts (structural fasteners) yield or break as they connect steel and other materials. Used in tunnels, bridges, buildings, cranes, and heavy equipment, fasteners are critical to  structural integrity and until now the ability to predict failure has been impossible. Now with the advent of Cleveland Electric Labs Brainy Bolt, a fiber optic insert located inside the fastener shaft, can detect strain, elongation, and tension on the bolt.  The insert is a fiber optic strain gauge and when connected  to an interrogator and an industrial computer the light waves are scanned and changed into digital messages regarding the load and stress on the bolt. A 5/8” bolt can supply clamping loads as high as 30,000 pounds. The Brainy Bolt is capable of detecting load changes of less than 1% of the maximum load.

About Fiber Optic Sensors

Cleveland Electric Laboratories  is active in development and applications of fiber optic sensors that do many things.  Some of the projects and markets include:

• Development
• Advancement & Applications of Fiber Optic Sensors
• Turbine Engines
• Health Monitoring of Aircraft
• Buildings
• Bridges
• Oil & Gas
• Transmission Systems
• Nuclear Power Plants
• Mines
• Petrochemical Plants
• Cranes
• Wind Turbines
• Mining
• Dams

Fiber optic sensors are being used to monitor temperature, pressure, strain, vibration, acceleration, load, fatigue and a multitude of other environmental factors.  Fiber optics can improve monitoring and save lives.

If you would like to know more about fiber optic sensing solutions, visit the www.clevelandelectriclabs.com website and view our many products and solutions.