Halbach Solenoid Magnetization for Deep PS Tendon Stress Sensing
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Solution Overview
Problem
Existing methods for measuring tension stress in prestressed concrete bridges are limited by the inability to effectively penetrate the magnetic field to deep parts of the bridge, leading to incomplete measurements and safety concerns due to aging structures.
Innovation Solution
An external magnetization system using multiple solenoid modules arranged in a Halbach array configuration, which generates a synthetic magnetic field capable of penetrating deep into prestressed concrete members, allowing for precise measurement of tension stress through the inverse magnetostrictive effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic field is applied to the entire exterior of an existing PSC girder, then the external magnetic field can be generated, but the magnetic field does not reach the PS tendon in deep parts due to magnetic field shielding caused by concrete and steel bars
Solution Approach 1:
The patent divides the single magnetization device into multiple solenoid modules (first, second, and third solenoid modules) arranged in a Halbach array. Each module generates a magnetic field that contributes to the overall synthetic magnetic field, enabling the magnetic field to penetrate deeper into the PSC girder and reach PS tendons in deep parts that were previously shielded by concrete and steel bars.
Solution Approach 2:
The patent combines the magnetic fields generated by multiple solenoid modules to create a synthetic magnetic field. The first solenoid module generates a magnetic field in a first direction, while the second and third solenoid modules generate magnetic fields in a second direction. These combined magnetic fields work together to overcome the shielding effect and achieve complete interior magnetization.
2Length of stationary object
If multiple solenoid modules are used to generate synthetic magnetic field, then deep penetration capability is improved, but the device complexity increases
Solution Approach 1:
The patent designs the multiple solenoid modules to perform multiple functions: each module not only generates magnetic field in its specific direction but also contributes to the overall synthetic magnetic field for deep penetration. The first solenoid module operates in the first direction while the second and third modules operate in the second direction, and all work together as a unified system for comprehensive interior magnetization and tension stress measurement.
Solution Approach 2:
The patent introduces a directional dimension by arranging solenoid modules in a Halbach array configuration with different orientations. The first solenoid module is oriented in the first direction, while the second and third modules are oriented in the second direction. This dimensional arrangement enables the synthetic magnetic field to penetrate deeper into the structure by utilizing multiple spatial dimensions rather than a single direction.
3Measurement precision
If conventional single magnetization device is used, then the device structure is simple, but the magnetic flux density for magnetizing PS tendon in deep part is not sufficient
Solution Approach 1:
The patent applies local quality by positioning solenoid modules at specific locations on the PSC girder surface. The first solenoid module is positioned to generate magnetic field in the first direction, while the second and third solenoid modules are positioned to generate magnetic fields in the second direction. This localized arrangement ensures that the synthetic magnetic field is concentrated where needed to achieve sufficient flux density in deep parts for accurate tension stress measurement.
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 enables precise measurement of tension stress in prestressed concrete bridges, improving safety assessments by accurately determining residual tension in deep parts of the structure, thus addressing the limitations of existing methods.
Implementation Method 1
generating a synthetic magnetic field capable of penetrating deep into prestressed concrete members
Implementation Method 2
multiple solenoid modules arranged in a Halbach array configuration
Implementation Method 3
measuring a tension stress of prestressed concrete (PC) members by utilizing an inverse magnetostrictive effect in which the permeability changes depending on the stress state of the magnetic body
Data Source
AI summary
Provided is an external magnetization system using multiple solenoid modules with a Halbach array. The external magnetization system comprises a support frame; a magnetization device including multiple solenoid modules arranged in a predetermined direction by a Halbach array along the support frame, and generating a plurality of magnetic lines in a predetermined direction for cross-sectional magnetization of a prestressed (PS) steel in a prestressed concrete (PC) member; a detection device measuring changes in a magnetic flux density associated with the plurality of magnetic lines; and A control device controlling the magnetization device in conjunction with the detection device.