Investigation On The Measurement Of Cable Tensions In Space Structures Based On The Elasto-Magnetic Method

Cable structure is one of the oldest kind of structures. The modern cable structure in China developed on 1970s. Nowadays, analysis and calculation for this kind of structures had been to a very advanced level. However, cable is the importance part of structure, so theory and methods of checking and measuring the tension of cable should have been developed. The EM method introduced in this paper is a new kind of method to measure the cable's tension. This method is also a lossless method which has high precision and stability.The EM is abstract of Elasto-magnetic. From Faraday's theory, if there is a system which has two coins, te direct current is imported into the primary coil. According to Faraday's law, at the same time, because there is cable in the center of this system, instantaneous current would be present in the second coil. So we can measure the instantaneous voltage. This voltage is depended on the magnetic permeability of cable. Therefore the magnetic permeability is also depended on the cable's stress. So the tensile stress of cable can be known by measuring the instantaneous voltage of second coil.In this paper, some other methods are introduced one by one and advantage, shortcoming and applicable field of methods also are expressed here.As the basic theory of the EM method, several kinds of knowledge are introduced in this paper such as mental theory, electrical theory and structural theory. And the basic theory of EM theory is also discussed.An experiment which can test the EM theory is introduced. From the result of this experiment, we can validate the practicality of EM method. And we developed a measure system from this experiment.And then, several experiments that used the EM sensor to measure the true project is introduced. These experiments include the model of AnHui university stadium, the model of China sail museum and the GuangDong Museum. The result of this experiment expressed that EM method has high precisionIn the finality, the problems requiring further studies are discussed.