- September 18, 2024
LVDT’s for Structural Health Monitoring
An LVDT (Linear Variable Differential Transformer) is an electromechanical sensor used to measure linear displacement. In the context of bridge monitoring, LVDT’s are commonly employed to measure the movement and deformation of bridge components, such as deck expansion, girder displacement, or bearing movement. Here’s how they are applied in bridge monitoring
How LVDT Works in Bridge Monitoring:
- Linear Displacement Measurement: LVDTs provide precise measurements of linear displacement by converting mechanical motion into an electrical signal. In bridges, they monitor the relative displacement between two points, which can indicate structural changes over time.
- Non-Contact Measurement: The LVDT sensor can measure displacement without requiring direct contact with the bridge surface, which is beneficial in harsh environments, reducing the risk of sensor damage.
- High Sensitivity and Accuracy: LVDTs offer high accuracy and are sensitive to minute changes in position, making them ideal for detecting subtle movements in bridges that could signal the onset of problems like cracking, tilting, or settlement.
- Long-Term Monitoring: LVDTs are used in Structural Health Monitoring (SHM) systems for long-term observation. They provide continuous or periodic data about the structural behaviour of the bridge under different loads, temperatures, and environmental conditions.
Applications in Bridge Monitoring:
Expansion Joints: LVDTs are installed to measure the movement at expansion joints, which naturally expand and contract due to temperature changes. Excessive movement might indicate problems with the joint.
Bearing Monitoring: LVDTs monitor the displacement in bridge bearings, which allow controlled movement of the bridge. Any abnormal bearing movement can be detected early to prevent potential failures.
Crack Monitoring: LVDTs can measure the widening or narrowing of cracks on bridge components, providing real-time data on crack progression.
Deck Deflection Monitoring: LVDTs monitor the vertical displacement of bridge decks, especially under load. Excessive deflection may signal a need for reinforcement or repairs.
Advantages of LVDTs in Bridge Monitoring:
Robust and Reliable: LVDTs are highly reliable in tough environmental conditions, including exposure to dust, moisture, and temperature variations.
High Repeatability: They provide consistent and repeatable measurements over long periods.
Wide Range of Measurement: LVDTs can measure both small displacements (micrometre level) and larger movements, making them versatile.
In bridge health monitoring systems, LVDTs are critical for ensuring structural integrity by providing early warning signs of potential structural issues. MeasureX offers wide range of LVDT’s which can measure from 2.5mm to 500mm
MeasureX LVDT’s features
- Operating range-2.5mm to 500mm
- Current consumption ≤10mA
- Frequency response up to 250Hz
- Accuracy of 0.25% FS
- Mechanical repeatability of ≤0.01%FS
- Can be customised as per client’s requirement.
https://www.measurex.com.au/product-category/displacement-sensors/lvdt/
