This technology is a low-cost RFID-based torque and tension sensor for high-performance fasteners, such as bolts, that are used in sophisticated high-tech equipment and systems. It offers the ability to remotely and quickly verify that a given fastener is torqued properly, resulting in potential cost-savings over the life of the fastener and its host system. The technology is also extremely low-cost compared to current torque sensing wrenches and comparable technologies. This asset management tool offers performance and safety improvements as well. The motivation behind this invention was the catastrophic event in which a NOAA satellite sustained heavy damage after falling from a Turn-Over-Cart (TOC). The root cause was a configuration change in which 24 bolts had not been secured properly to the TOC. With this NASA invention, the quality assurance, tension monitoring, and configuration management associated with proper torqueing of fasteners will be largely automated, therefore providing a higher degree of safety.
The NASA-developed RFID torque and tension sensing tag system replaces traditional designs by using standard bolts in conjunction with an RFID ring integrated circuit (IC), antenna layers (top and bottom), a flat washer, and a spring washer. The antenna, RFID ring, and spring washer comprise a sensor tag that can be remotely interrogated. When sufficient torque is applied to the bolt, the RFID circuit is enabled, allowing it to communicate with remote RFID interrogators (typically 3 to 30 feet away, depending on the tag antenna design). A new level of automation and sensor telemetry is now possible due to this technology's ability to read longer ranges than the present systems. This system's cost saving has the potential to revolutionize the asset management industry, allowing for more products to be monitored for torque and tension.
This is a passive device, meaning that even when the RFID ring circuit is complete, it will only provide an RF response when activated by an external reader. The RFID IC chip is a standard EPC Global Class 1, Gen 2 design that is commercially available and routinely employed in tracking and supply chain logistics applications. For torque applications (not necessarily for tension monitoring applications), the design must be tailored to the operational concept and possibly to the environment in which the fastener will be used. For example, the distance from which the signal must be read impacts the tag antenna design, and the environment impacts characteristics of the spring washer. The system can also be used to monitor tension on a fastener over time.
Potential applications include use in automotive systems, shipbuilding, complex construction, and heavy equipment manufacturing.