How Wireless Sensors Measure Strain: Principles and Applications

Wireless sensors have transformed how we monitor the health of infrastructure, especially in measuring strain. Traditional strain measurement methods often involve wired sensors, which can be complex and prone to maintenance issues. Wireless technology offers numerous advantages in terms of ease of installation, data transmission, and remote monitoring.

What is Strain Measurement?

Strain measurement refers to the process of quantifying deformation in an object due to applied forces. It is a dimensionless quantity that quantifies the degree of deformation. In civil engineering and construction, accurate strain measurement and data is important for understanding the behaviour of materials and structures under load. When a material is subjected to stress, its shape changes, and this deformation—whether elongation or compression—can be detected and measured.

Strain gauges are one of the most common tools for this purpose. These instruments measure the slight changes in length when a structure is subjected to external forces. Strain data helps engineers understand how much load a structure can handle and whether it’s nearing failure.

Why Monitoring Strain is Important for Infrastructure?

Aging infrastructure, coupled with increasing load demands, makes strain monitoring an important aspect of structural health management. It is essential for infrastructure that handles high stress, such as bridges, dams, and large buildings. By continuously measuring strain levels, engineers can:

• Identify potential structural weaknesses: Detect signs of fatigue, cracking, or other damage before they escalate.
• Assess the impact of loads: Evaluate the response of structures to various loads, such as traffic, wind, or earthquakes.
• Optimize maintenance: Schedule repairs and maintenance based on real-time strain data, reducing downtime and costs.
• Ensure public safety: Prevent catastrophic failures by monitoring the structural health of critical infrastructure.

Wireless Sensors for Strain Monitoring

With the advent of wireless technology, strain monitoring has become much more accessible and efficient. Unlike traditional wired sensors, wireless strain sensors offer numerous advantages, including ease of installation, reduced costs, and the ability to monitor structures in real time from remote locations.

Wireless strain sensors are particularly advantageous for large, hard-to-reach infrastructure such as bridges or wind turbines, where manual data collection would be time-consuming, expensive, and risky. Wireless technology allows engineers to receive continuous data without the need for frequent site visits.

Working Principle of Wireless Strain Measurement Sensors

The principle behind wireless strain measurement is relatively simple but highly effective. Wireless strain sensors, like the Resensys Wireless Strain Gauge SenSpot™ Sensors, utilize strain gauges to detect minute changes in deformation. The sensor converts the detected strain into an electrical signal. This signal is transmitted wirelessly to a data collection point, often a gateway like Resensys’ solar-powered SeniMax™ gateway.

This system allows for real-time data acquisition, remote communication, and the ability to monitor infrastructure continuously. Engineers can track stress, strain, and other important factors remotely, ensuring optimal performance and safety.

Wireless Strain Gauge SenSpot™ Sensors at Bridge Structure

Strain Measurement with Resensys Sensors

Resensys offers wireless strain sensors designed for the structural health monitoring (SHM) of critical infrastructure. The Wireless Strain Gauge SenSpot™ sensor is designed for applications that require precise, real-time strain measurements. This product provides continuous, reliable monitoring, allowing engineers to detect structural fatigue early and prevent possible failures.

In addition to strain, Resensys sensors can measure various parameters, including temperature, vibration, and inclination, offering a complete solution for monitoring infrastructure health. Resensys’ system utilizes wireless technology to collect and transmit strain data, making it a leader in remote construction and infrastructure monitoring solutions.

Applications of Wireless Strain Monitoring

Wireless strain monitoring is used across various sectors where infrastructure health is prime:

1. Bridges: Bridges experience constant stress from traffic, weather, and environmental changes. Monitoring strain in real time allows for immediate action when necessary, minimizing the risk of collapse.
2. Tunnels: Similar to bridges, tunnels bear the weight of roadways and must maintain their structural integrity despite heavy loads and environmental conditions.
3. Dams: Dams handle significant water pressure. Monitoring strain ensures their continued safety and performance, preventing catastrophic events.
4. Wind Turbines: Strain monitoring is crucial for the ongoing maintenance of wind turbines, particularly in areas subject to high winds.
5. Buildings: High-rise buildings, especially those in earthquake-prone zones, benefit from strain monitoring to detect likely weaknesses.

Installed Wireless Strain Gauge SenSpot^TM sensors on Trunnions of a  Dam Structure

Case Study

A prime example of the effectiveness of wireless strain monitoring is Resensys’ application at NASA’s Kennedy Space Center. Resensys’ wireless strain sensors, along with other advanced monitoring devices like the accelerometer and tiltmeter SenSpot™ sensors, are used to monitor the structural health of NASA’s movable bridges at Cape Canaveral, Florida.

These bridges experience immense stress as they transport spacecraft and heavy loads, making real-time strain monitoring crucial. By using solar-powered gateways like the SeniMax™, NASA ensures that all critical infrastructure components are closely monitored for strain and deformation, ensuring safe operations in a challenging environment. The strain gauge SenSpot™ plays a vital role in detecting structural fatigue, providing accurate data for timely maintenance and repairs.

Wireless Strain Gauge SenSpot^TM at Bridges NASA’s Kennedy Space Center

Advantages of Wireless Strain Monitoring

Wireless strain monitoring offers several benefits:

• Cost-effective: Do not need extensive wiring and manual inspections.
• Real-time data: Provides instant feedback on structural health, allowing for quick interventions.
• Remote monitoring: Data can be collected and analysed remotely, saving time and labor.
• Long-lasting: Resensys’ wireless strain sensors have a long lifespan and require minimal maintenance.
• Provide Alert Services: Alert generation and management with customizable alert levels, automated structural diagnostics, capability of providing e-mail or text message alerts

Conclusion

Wireless strain gauge sensors are essential tools for structural health monitoring. By providing real-time, accurate data on strain and other structural parameters, wireless sensors enable preventive maintenance, which ultimately saves costs and ensures the safety of bridges, tunnels, dams, and other key infrastructure.

Contact us today to learn more about how Resensys can help monitor strain and how wireless strain gauge sensors can benefit your structural health monitoring needs. Our experts can provide tailored solutions and support to meet your specific requirements.