Fluid-Filled Cavity Deformation Sensor for Structural Monitoring
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Solution Overview
Problem
Existing methods for measuring deformations in structural elements, particularly in building constructions, face challenges such as limited accuracy due to heterogeneity in concrete materials, reliability issues from electrical drifts and durability problems, and unsuitable device dimensions for local detection, as well as complexity in installation and high costs. Additionally, traditional systems struggle with measuring deformations in concrete under tension and are affected by environmental factors.
Innovation Solution
An integrated system that incorporates a cavity oriented perpendicular to the structural element's central longitudinal axis, filled with a compressible fluid, which measures deformation by detecting pressure and temperature variations within the cavity, allowing for precise estimation of deformations without flexural contributions and enabling multiple point measurements along the structural element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional measurement devices (electrical strain gauges, optical fibers) are applied to concrete surfaces or embedded in concrete, then deformation measurements can be obtained, but measurement accuracy deteriorates due to material heterogeneity, adhesion issues, and local cracks
Solution Approach 1:
The patent introduces a fluid-filled cavity as an intermediary measurement medium. Instead of directly bonding sensors to the heterogeneous concrete surface or embedding them in the concrete matrix, the system uses a fluid (liquid or gas) contained within a sealed cavity to transmit and amplify deformation signals. This intermediary approach eliminates adhesion problems and material heterogeneity issues, as the fluid uniformly transmits stress changes from the cavity walls to the measurement devices.
Solution Approach 2:
The patent replaces traditional mechanical bonding systems (strain gauges bonded to surfaces) with a fluid-based transmission system. The fluid-filled cavity converts structural deformations into pressure and temperature variations, which are then measured by non-contact or minimally-contacting sensors. This substitution eliminates the need for mechanical adhesion between measurement devices and the structural material, thereby improving reliability.
2Loss of information
If measurement devices are embedded inside structural elements during casting, then internal deformation data can be obtained, but device complexity and installation difficulty increase due to the need for support frameworks
Solution Approach 1:
The patent merges the measurement cavity directly into the structural element itself during the casting process. The cavity is formed as an integral part of the concrete structure, eliminating the need for separate support frameworks or complex embedding procedures. This integration simplifies installation while ensuring that deformation measurements are obtained from within the structural element.
Solution Approach 2:
The measurement cavity is prepared and positioned before the concrete casting process. By pre-forming the cavity and placing the fluid-filled measurement system in position before casting, the patent avoids the complexity of installing measurement devices after the structure is built. This preliminary action ensures that the cavity is properly integrated into the structural element without requiring complex support frameworks during or after casting.
3Area of stationary object
If measurement bases are spaced far apart to cover larger structural dimensions, then broader structural monitoring is achieved, but measurement precision deteriorates due to averaging effects over large distances
Solution Approach 1:
The patent divides the structural element into multiple segments by placing several fluid-filled cavities at different locations along the structure. Each cavity provides independent local deformation measurements, allowing the system to achieve both broad coverage (by distributing multiple cavities) and high precision (by measuring local deformations at each cavity position). This segmentation eliminates the need for long measurement bases while maintaining comprehensive monitoring coverage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides accurate, reliable, and cost-effective deformation measurements, with improved linearity and reduced hysteresis, suitable for structural monitoring, especially in steel reinforcement elements, and is more practical to install with minimal disruption to the structural integrity.
Implementation Method 1
the cavity undergoes a deformation, which causes a variation in the pressure and temperature of the fluid inside
Implementation Method 2
the cavity undergoes a deformation, which causes a variation in the pressure and temperature of the fluid inside
Implementation Method 3
filled with a compressible fluid
Implementation Method 4
it is possible to estimate the volume variation of the cavity (from which it is possible to trace the value of the deformation)
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3
AI summary
An integrated measuring system (9) comprises a structural element (10) for building constructions, having an internal cavity (14), hermetically closed to contain a compressible fluid (16), and a measuring system (12) for measuring stresses and/or deformations on the structural element (10), measuring system (12) whereby it is possible to measure the pressure and temperature of the fluid (16) so as to measure a change in fluid pressure and determine a variation of the volume of the cavity (14) resulting from an action (F) imparted to the structural element (10).