Fiber Bragg Grating Strain Sensors for Creating Modern Sophisticated Equipment

Strain measurement is imperative during prototype design and testing. Strain measurements ensure that materials perform as they should and that the equipment is safe and durable. Measuring strain is crucial for testing complex structures, like aircraft, turbines, etc. There multiple ways in which stress can be measured. However, it is widely accepted that FBG sensors are the most efficient way of strain measurement. FBG sensors provide multiple advantages over other methods:

1) high sensitivity;

2) small size;

3) ability to be mounted on any surface;

4) immunity to electromagnetic interference;

5) reliability even in harsh environments;

6) low sensitivity to vibration and heat.

FBG strain sensors are used in wing load testing to determine the structure’s performance and possible limitations under the lifting forces during flight. There are several benefits that FBG strain sensors offer to the aerospace field for this type of application. For instance, FBG technology provides strain measurement using a big number of continuous sensors which ensures maximum coverage from a single optical fiber. The immunity to electromagnetic interference, radio frequency interference and other electrical influences makes FBG strain sensors ideal for use in hazardous environments, such as flight. Also, FBG sensors are less cumbersome to install. In addition, the FBG strain sensor prices are expected to decrease by 20% which will open up new opportunities for various markets.

The repeated loading and unloading of a material causes fatigue. It is estimated that around 90% of structural failures are a result of fatigue. To determine the breaking point of a structure, fatigue tests are performed. The tests indicate the number of loading cycles until failure. FBG sensors are able to provide real-time data on strain fields and load distributions. The immunity to both low and high temperatures enables the sensors to be monitored during the high-temperature cure phase of composite fabrication. The fatigue life of an FBG strain sensor far surpasses that of other methods of strain measurement.

The tendency to build longer wind turbines with longer blades complicates the maintenance. The design of stronger, lighter materials is necessary, however small imperfections during the manufacturing process can cause failures. FBG strain sensors may provide real-time knowledge of load distributions and turbine blade shape. This data will provide valuable information on the needed adjustments to the blades manufacturing.

Optromix, Inc. is a U.S. manufacturer of innovative fiber optic products for the global market, based in Cambridge, MA. Our team always strives to provide the most technologically advanced fiber optic solutions for our clients. Our main goal is to deliver the best quality fiber optic products to our clients. We produce a wide range of fiber optic devices, including our cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Optromix, Inc. is a top choice among the manufacturers of fiber Bragg grating monitoring systems.

If you have any questions, please contact us at info@optromix.com

 

 

Ubiquitous optical fiber strain sensors against a background of large-scale urbanization

FBG strain sensors in urbanization processFiber Bragg gratings are often used in strain sensing especially in such places where the environment is harsh (for instance, high-EMI, high-temperature, or highly-corrosive). Strain measurement is imperative during prototype design and testing. Strain measurements ensure that materials perform as they should and that the equipment is safe and durable. Measuring strain is crucial for testing complex structures, like aircraft, turbines, etc. There various ways in which stress can be measured, but it is widely accepted that FBG sensors are the most efficient way of strain measurement.

There are two types of applications of the fiber Bragg grating strain sensors:

  • Long-term Static Strain Sensing. The main issue in the long-term static strain test is an interest in measuring the long-term static strain of the component in question. In order to carry out the above operation, it is necessary to set up the grating on the structure, find out what the initial wavelength is, and then within a set period of time to detect and record the changes that have occurred. Also, it is possible to return to the structure, reattach, and refer back to the initial wavelength. As a result, it becomes possible to obtain the determination of what this strain is from the initial condition at that time. The ability to disconnect your monitoring instrumentation and return for results after a large amount of time such as months or even years is a very great advantage of fiber Bragg grating sensors. For instance, in the case of bridges, it is common for engineers to visit the bridge and conduct the impact testing using an impact hammer on the different parts of the bridge. This is time-consuming and even hazardous because of the height of some bridge structures. The distribution of a number of FBG sensors throughout the bridge and the attachment of the instrumentation to this bridge on a periodic basis is a much more efficient solution. This is only one of the good examples to demonstrate the effectiveness of the fiber Bragg grating strain sensors. Besides bridges, other examples of using FBG for long-term static strain testing are buildings, piers, and structures in high earthquake-prone areas.
  • Dynamic Strain Sensing. The different structures may have very-low-frequency modes, and they may also have higher modes due to the effects of wind and tide. Most earthquakes and other earth tremors are low-frequency events.  Fiber Bragg gratings can be attached to the structures and monitored for the vibrations during the earth’s tremors and earthquakes. The low-frequency dynamic strain testing can help in determining the reaction of high-rise buildings to the wind. In addition to this, FBG sensors create connections with peers and other shore structures to determine their vibrations during the ebb and flow of tides. Dynamic strain testing can also be performed on transportation vehicles like automobiles, trains, and airplanes. In addition to civil structures and vehicles, there are a number of other applications for dynamic strain testing and vibration stress testing using fiber Bragg gratings. FBG sensors can be attached to industrial machinery to determine the frequency and amplitude of the stress vibrations.  

Optromix, Inc. is a U.S. manufacturer of innovative fiber optic products for the global market, based in Cambridge, MA. Our team always strives to provide the most technologically advanced fiber optic solutions for our clients. Our main goal is to deliver the best quality fiber optic products to our clients. We produce a wide range of fiber optic devices, including our cutting edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems.

If you would like to purchase Optromix FBG Strain Sensors, please contact us: info@optromix.com or +1 617 558 98 58

 

Fiber Bragg grating sensors for biomechanics and rehabilitation applications

Fiber Bragg grating sensors are becoming increasingly popular and attractive for biomechanics and rehabilitation applications due to their advantageous properties like small size, lightweight, biocompatibility, chemical inertness, multiplexing capability, and immunity to electromagnetic interference. FBG sensors have been utilized in a variety of different applications, such as aeronautics, automotive, civil engineering structure monitoring, and undersea oil exploration. The use of fiber optic sensors for biomechanics and rehabilitation applications is very recent. The full-scale implementation has not been done yet.

FBG strain sensors can be used to measure strain in bones, stresses in intervertebral discs, pressure distribution in Human Machine Interfaces (HMIs), forces induced by tendons and ligaments,  shrinkage stresses in bone cement during polymerization. FBG displacement sensors could be used to measure chest wall deformations, angles between body segments during gait. FBG sensors are especially useful in dental biomechanics.

Applications of fiber Bragg grating sensors in biomechanics and rehabilitation engineering:

  1. Monitoring of biomechanical behavior of the musculoskeletal system;

The measurement of strain on the bones is crucial for understanding bone diseases and in designing medical devices. The measurement of bone strain is conducted using FBG strain sensors, which helps to study the effects of fracture fixation plates. FBG strain sensors can also be used to understand to what extent the bone calcium loss affects the strain response of bone

  1. Strain measurement of bone cement;

Damage to bone cement caused by dynamic loading is one of the main causes of hip replacement failures. The studies of human bone models using FBG strain sensors could be useful to verify the action of the cement, both during the curing process and after consolidation.

  1. Pressure mapping and the measurement of contact forces and stresses of orthopedic joints;

The understanding of contact stress at orthopedic joints is necessary for prostheses research and biomechanics studies. Due to the flexibility and multiplexing capability, FBG sensors are suitable for irregular-shaped interface surfaces, like a knee joint.

  1. Measurement of pressure distribution at the intervertebral disc;

FBG pressure sensors have outperformed other means of measuring pressure distribution at the intervertebral disc due to the small size and biocompatibility.

  1. Dental biomechanics;

FBG sensors are already used in dental applications, for example, monitoring the force and temperature as a function of time in dental splints worn by patients suffering from sleep apnoea.

  1. Monitoring of chest wall movement during respiration.

The studies of biomechanics have benefited greatly from the implementation of FBG sensors to measure chest displacement during respiration. The FBG sensors are embedded into a chest deformable strap which is strained in accordance with the deformation of the chest.

If you are interested in Optromix FBG sensors, please contact us at info@optromix.com

The use of FBG sensors in intelligent textiles

Medical textiles are an exciting idea that has the potential to significantly improve people’s lives. The use of textiles for medical purposes has a long history, and they are still used in the healthcare industry today. Traditionally, the textile industry was confined to the production of fibers and fabrics; modern technology allows the applications of textiles to expand. Recently, important developments have been made in enhancing the capabilities of textiles to respond to environmental stimuli. These textiles are called smart textiles; they possess the properties of conventional textiles and also carry additional functional values.

Smart textiles correspond with a wide area of products, as well as studies, that enhance the usefulness and functionality of conventional fabrics by using woven or non-woven structures that connect with the environment or users. The structures have the capability to sense environmental conditions.

There are multiple kinds of smart textiles that are used nowadays, one of them being E-textiles, or electronic textiles. E-textiles include smart health monitoring devices and sensors within the clothing that sense and record the basic bodily functions like body temperature, respiration, the functioning of a heart, etc. The data collected by the sensors is then transmitted to healthcare centers or hospitals. Fiber optic technology is widely incorporated in smart textiles in the form of sensors. Fiber optic sensors are used due to multiple advantages that they present, like low zero drift, large bandwidth, flexibility, good accuracy, immunity to electromagnetic interference, etc. Over the years fiber optic sensors have also become cheap and easily accessible.

Different fiber Bragg grating sensors are used in a variety of smart fabrics. Some of the FBG sensors that are used in smart fabrics include:

  • Stretch-sensitive sensors;

FBG strain sensors are used for monitoring and sensing body parameters. The sensors are used for determining respiration, movement, blood pressure, heart rate.

  • Temperature sensing;

FBG temperature sensors provide temperature monitoring on skin surfaces

as well as the near-body environment. These sensors are often incorporated in combat clothing.

  • Sensing harness;

FBG strain sensors and FBG displacement sensors are placed to measure abdominal and thoracic movements caused due to breathing activity without corrupting signals or overlapping signals.

Optromix, Inc. is a U.S. manufacturer of innovative fiber optic products for the global market, based in Cambridge, MA. Our team always strives to provide the most technologically advanced fiber optic solutions for our clients. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line: fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Temperature Sensing (DTS) systems. We create and supply a broad variety of top-notch fiber optic solutions for the monitoring of various facilities all over the world.

If you are interested in Optromix FBG sensors, please contact us at info@optromix.com

Fiber Bragg grating for shallow landslide triggering detection

Shallow landslides pose a serious threat to structures situated in close proximity. The most dangerous are some flow-like landslides that travel at significant rates for long distances. The detaching area is the starting point for flow slides that erode and engage large amounts of soil along their path and may discharge great impact energy to engineering structures.

The detection of landslide triggers has been an important issue for many years; significant efforts have been undertaken to understand the mechanisms responsible for landslide triggering, as well as to identify the first signs of soil instability. This information will aid in the development and implementation of effective early warning systems. Among triggering, factors for a landslide are slope saturation, groundwater seepage, excavation, erosional processes, seismic action, etc. All these factors increase shear stress and pore water pressure, which in turn cause sliding surfaces due to high strain in the sliding mass. The strain increases with the approach of flow sliders; the strain increases exponentially as the landslide approaches. Soil instability follows, which causes erosion.

Therefore, the strain is the most important parameter for landslide monitoring. In recent years, fiber optic technology has attracted significant interest due to the multiple advantages that it provides. Fiber optic strain sensors are already widely used in geotechnical applications, including landslide monitoring. recently, the results of experiments involving FBG strain sensors have revealed that FBG sensors can be successfully used for measuring strain in the soil since it is possible to effectively couple the fiber cable with the soil.

One of the most attractive attributes of FBG strain sensors for landslide triggering detection is that FBG sensors do not interfere with the phenomenon that they are designated to monitor.

Optromix, Inc. is a U.S. manufacturer of innovative fiber optic products for the global market, based in Cambridge, MA. Our team always strives to provide the most technologically advanced fiber optic solutions for our clients.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line: fiber Bragg grating sensors, FBG interrogators, and multiplexers, Distributed Temperature Sensing (DTS) systems. We create and supply a broad variety of top-notch fiber optic solutions for the monitoring of various facilities all over the world.

If you are interested in Optromix FBG strain sensors, please contact us at info@optromix.com

Fiber Bragg grating strain sensors for structural health monitoring

Fiber Bragg gratings stand out among other fiber optic sensors as the most developed and prominent technology for the measurement of strain, vibrations, temperature, and pressure. FBG sensors have attracted significant interest in structural health monitoring due to numerous advantageous properties:

  1.  immunity to electromagnetic interference;
  2. intrinsic fire safety;
  3. low invasiveness;
  4. minimum aesthetic impact;
  5. possibility to send the data remotely using the same sensing fiber.

There are multiple sensing advantages that FBG sensors provide. First of all, FBG sensors perform with an excellent balance between complexity and performance, which is one of the most attractive qualities of fiber Bragg grating sensors for structural health monitoring. Secondly, FBG sensors are able to work in low signal-to-noise ratios better than other optic sensors. Moreover, fiber Bragg grating sensors are predictable and less dependent on the temperature of the surrounding environment, as well as are well-suited for multiplexed optical sensor networks.

Over the past decade, structural health monitoring has attracted a lot of attention as modern technology develops, and new materials and compounds are used in the construction of buildings and structures. Structural health monitoring involves the collection and analysis of information obtained through measurements of the structure. The results of data analysis are used to assess the damage and evaluate the performance of the structure under harsh conditions.

FBG sensor structural health monitoring has become an important tool for assessing the performance of different structures and measurements of temperature, strain, pressure, displacement, etc.

Fiber optic strain gauge is welded directly to the surface of the metal structure (pipes, beams, etc.), and it has a protective silicone cover. Fiber optic strain sensors are durable and stable, widely used for civil engineering constructions, particularly they reinforce concrete structures exceptionally well.

Fiber Bragg Grating strain sensors demonstrate lots of advantages compared to the regular electrical strain gauges. Namely, they are immune to electromagnetic interference and power shortages. Compact size devices provide the most accurate measurements. FBGs are, literally, the best strain sensors right now.

If you would like to purchase Optromix FBG Strain Sensors, please contact us: info@optromix.com or +1 617 558 9858

Measurement of strain with strain gauges and FBG strain sensors

The relationship between stress put on a material and the resulting deformation is defined by Hooke’s Law that has been around since 1678. Different techniques and technologies have been used to measure the law over different periods of time. In the past mechanical strain gauges have been used to measure strain applied to a material. The first strain gauges were analog. Some of these devices, like springs and levers, are still used today, but they are not accurate enough as the strain applied to the material would have to be quite high for the device to register it. Strain gauges have a number of disadvantages, one of them being the need to be clamped firmly so the device didn’t move which causes an inaccurate reading.

The next step in strain measurement techniques were resistive strain gauges, the most common of which are foil resistive gauges. These devices are better than the previous model as they are sensitive, accurate, easier to produce. However, the lack of foil elasticity poses limitations on the device, for example, resistive strain gauges cannot be used for ductile materials. To overcome this downside conductive material can be added to elastomers for a stretchier gauge.

The best solution that has been developed so far for strain measurements are fiber Bragg grating strain sensors. They are still catching on as their initial price and lack of awareness slowed their adoption among industry professionals. However, the price of FBG strain sensors is dropping every year which is tied with the level of development of fiber optic technology.

The low price of FBG sensors makes them available for different applications, some of which include automotive, medical, aerospace, and energy markets. FBG strain sensors have been found to be useful in aerospace applications where they are used to determine wing loading while providing accurate fuel readings. Civil engineers utilize FBG sensors for structural health monitoring. The operational life of vehicles can be determined with the use of FBG sensors that are widely utilized by automotive designers. FBG strain sensors are lighter, easier to install, and less expensive than strain gauges.

Optromix, Inc. is a U.S. manufacturer of innovative fiber optic products for the global market, based in Cambridge, MA. Our team always strives to provide the most technologically advanced fiber optic solutions for our clients.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line: fiber Bragg grating sensors, FBG interrogators, and multiplexers, Distributed Temperature Sensing (DTS) systems. We create and supply a broad variety of top-notch fiber optic solutions for the monitoring of various facilities all over the world.

If you are interested in Optromix FBG strain sensors, please contact us at info@optromix.com

Crack monitoring of wind turbine foundations using FBG strain sensors

FBG strain sensors for crack monitoringThe increased demand for energy due to the growing population has forced the industry to develop new sustainable ways to produce energy. Among new and developing energy technologies are wind turbines. They are widely used to produce energy in many parts of the world. However, there are multiple concerns that are yet to be solved, one of them has been the lack of effective monitoring devices and techniques. Structural health monitoring of wind turbines is needed to ensure that the infrastructure around wind power remains reliable. It is crucial to monitor the operation of wind turbines to ensure effective wind power generation and avoid costly downtimes.

Besides monitoring of wind turbine temperatures, which can be effectively performed with the use of FBG temperature sensors, the monitoring of wind turbine foundations can prevent premature decay of the foundations and prolong the operational time of the turbines. Often the access to the underground part of the foundations is limited, therefore the degradation of onshore, reinforced-concrete wind turbine foundations is assessed via above-ground inspections, or through excavations that suspend energy generation. Sustained measurements of crack behavior could be used to quantify the risk of water ingress and reinforcement corrosion. However, the cracks that occur during turbine operation are not monitored. A solution to this issue is the use of fiber Bragg grating sensors.

Subterranean fiber Bragg grating strain sensors can be used to monitor the opening and lateral displacements of foundation cracks during wind turbine operation. Cracks that occur in the foundation of the turbines are often caused by the vibrations that are produced by turbines themselves. Therefore crack displacement results that are obtained via FBG strain sensors installed on the foundations are correlated with the strains measured by the second series of FBG sensors affixed to the turbine tower and verified against wind speed and turbine data from the operator.

The use of FBG strain sensors can be used to better assess the risks of water ingress and subsequent corrosion of the foundation’s steel reinforcement. The data obtained by fiber Bragg grating sensors may help engineers to more accurately determine the current asset lifetime and the design and construction of foundations in the future.

Fiber Bragg grating strain sensors demonstrate lots of advantages compared to the regular electrical strain gauges. Namely, they are immune to electromagnetic interference and power shortages. Compact size devices provide the most accurate measurements. FBGs are, literally, the best strain sensors right now.

If you would like to purchase Optromix FBG Strain Sensors, please contact us: info@optromix.com or +1 617 558 9858

Fiber Bragg grating strain sensors in prototype testing

FBG strain sensors in prototype testingStrain measurement is imperative during prototype design and testing. Strain measurements ensure that materials perform as they should and that the equipment is safe and durable. Measuring strain is crucial for testing complex structures, like aircraft, turbines, etc. There are multiple ways in which stress can be measured; however, it is widely accepted that FBG sensors are the most efficient way of strain measurement. FBG sensors provide multiple advantages over other methods: 1) high sensitivity; 2) small size; 3) ability to be mounted on any surface; 4) immunity to electromagnetic interference; 5) reliability even in harsh environments; 6) low sensitivity to vibration and heat.

FBG strain sensors are used in wing load testing to determine the structure’s performance and possible limitations under the lifting forces during flight. There are several benefits that FBG strain sensors offer to the aerospace field for this type of application. For instance, FBG technology provides strain measurement using a big number of continuous sensors which ensures maximum coverage from a single optical fiber. The immunity to electromagnetic interference, radio frequency interference, and other electrical influences makes FBG strain sensors ideal for use in hazardous environments, such as flight. Moreover, FBG sensors are less cumbersome to install. In addition, the FBG strain sensor prices are expected to decrease by 20% which will open up new opportunities for various markets.

The repeated loading and unloading of material causes fatigue. It is estimated that around 90% of structural failures are a result of fatigue. To determine the breaking point of a structure, fatigue tests are performed. The tests indicate the number of loading cycles until failure. FBG sensors are able to provide real-time data on strain fields and load distributions. The immunity to both low and high temperatures enables the sensors to be monitored during the high-temperature cure phase of composite fabrication. The fatigue life of an FBG strain sensor far surpasses that of other methods of strain measurement.

The tendency to build longer wind turbines with longer blades complicates the maintenance. The design of stronger, lighter materials is necessary, however small imperfections during the manufacturing process can cause failures. FBG strain sensors may provide real-time knowledge of load distributions and turbine blade shape. This data will provide valuable information on the needed adjustments to the blades manufacturing.

Optromix, Inc. is a U.S. manufacturer of innovative fiber optic products for the global market, based in Cambridge, MA. Our team always strives to provide the most technologically advanced fiber optic solutions for our clients. Our main goal is to deliver the best quality fiber optic products to our clients. We produce a wide range of fiber optic devices, including our cutting edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. If you have any question about FBG strain sensors, please contact as info@optromix.com

Fiber Bragg grating sensors in aerospace applications

FBG sensors in aerospace applicationsAll engineering infrastructures undergo aging. The damage that appears over time is a consequence of the loads applied to them, therefore regular maintenance actions are required in order to predict the lifetime of these structures and lengthen it, which, in turn, will aid in avoiding catastrophic failures. Aviation-related infrastructures demand the highest levels of damage detection as these structures are overwhelmingly built according to a damage-tolerant principle. The structures for aerospace are designed to withstand damages with certain characteristics. Damage-tolerant design involves considerable effort for structure inspection. The inspections and maintenance tasks need to be periodic and scheduled; these are essential for safe and efficient operations.

Automation of the inspection processes is a point of capital importance to reduce inspection efforts, as maintenance is time-consuming and costly. Fiber Bragg grating sensor systems can perform real-time inspection which leads to a reduction of maintenance costs and improved the reliability and performance of the structures. Therefore, there is great interest in developing FBG sensors from the industry and academia. The most promising sensors are FBG strain sensors, FBG temperature sensors, FBG accelerometers, etc.

The intrinsic capabilities of FBG sensors, such as insensitivity to electromagnetic radiation, lightweight, small size, high sensitivity and resolution, and, most importantly, their suitability to be embedded into structures, make them suitable for most aerospace applications.

Among different approaches to a maintenance system based on FBG sensors deployment are: 1) single-point sensors; 2) distributed sensing, including distributed temperature systems. Distributed temperature sensing (DTS) systems are optoelectronic devices that measure temperatures by means of optical fibers functioning as linear sensors. Temperatures are recorded along the optical sensor cable, thus not at points, but as a continuous profile. High accuracy of temperature determination is accomplished over great distances.

The successful application of FBG sensors to aircraft requires the sensors to provide reliable and accurate information about the condition of the structure and to reduce economic losses caused by unproductive downtimes. At this moment, FBG sensors and FBG based systems, such as DTS, are the most appropriate solution to most aerospace needs.

Optromix will write a tailored fiber Bragg grating-based on your specific requirements, which can be used with any type of optical fiber sensor technology. We will make sure to analyze your fiber optic applications and deliver the most suitable solution.

If you would like to purchase FBGs, please contact us: info@optromix.com or +1 617 558 9858