Application of Magnetic Sensor for Non-Destructive Stress Measurement for Steel Structures.
Event details
| Date | 20.09.2012 |
| Hour | 14:00 › 16:00 |
| Speaker | Prof. S. Akutagawa of Kobe University, Japan (invited professor at LMR) |
| Location |
GC D0 386
|
| Category | Conferences - Seminars |
A magnetic anisotropy sensor is used for nondestructive measurement of stress on surfaces of H-beams used as structural elements in tunnel support systems. The sensor is built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of a ferromagnetic material, such as steel, are measured and converted to absolute values of stresses existing on the surface of the material. Proper treatment of boundary conditions allows determination of stress tensor completely on surface of H-beam flanges, with average error of 10 to 20MPa.
A series of stress measurement was conducted for Hbeams in NATM tunnels. The results obtained from the field stress measurement were in full accordance with the findings made from the previous series of measurement in a lab. The sensor used in this study is small, easy to carry around even into a tunnel, for example, and allows direct, nondestructive measurement of absolute values of stresses on surface of steel. The use of this sensor is not limited to H-beams and it can
be applied in any situation where surfaces of steel, in the forms of beams, plates, pipes, walls, etc. are exposed for human access. Not only a direct use of the results of stress measurement is beneficial in numerous civil and mining engineering applications, but also a secondary use of the information for interpretation of deformational behavior of structures in concern, in this case a tunnel, is also possible.
A case study for evaluation of axial force in ground anchor is also introduced. With a unique characteristics of the magnetic sensor for stress reading during plastic deformation, a novel method is briefly discussed for estimation of the maximum load exerted on a steel product in the past.
A series of stress measurement was conducted for Hbeams in NATM tunnels. The results obtained from the field stress measurement were in full accordance with the findings made from the previous series of measurement in a lab. The sensor used in this study is small, easy to carry around even into a tunnel, for example, and allows direct, nondestructive measurement of absolute values of stresses on surface of steel. The use of this sensor is not limited to H-beams and it can
be applied in any situation where surfaces of steel, in the forms of beams, plates, pipes, walls, etc. are exposed for human access. Not only a direct use of the results of stress measurement is beneficial in numerous civil and mining engineering applications, but also a secondary use of the information for interpretation of deformational behavior of structures in concern, in this case a tunnel, is also possible.
A case study for evaluation of axial force in ground anchor is also introduced. With a unique characteristics of the magnetic sensor for stress reading during plastic deformation, a novel method is briefly discussed for estimation of the maximum load exerted on a steel product in the past.
Practical information
- General public
- Free
Organizer
- ENAC-LMR (andrea.delisio@epfl.ch)
Contact
- cadax@kobe-u.ac.jp