Tensile Stress Measurement of Tendon by Means of Non-contact Yoke Method

In this study, we have constructed a measuring system to investigate tensile stress measurement of tendons, which is employed in bridges, by means of the non-destructive and non-contact method. The measuring system consists of tensile stress applying apparatus up to 2 GPa, and power supply for ac and dc current to tendon directly to magnetize tendon in circular direction and to coil wound on yoke to magnetize tendon in axial direction. We have used two kinds of tendon, which were produced by different companies, using the measuring system constructed in this work. Two kinds of experiments are carried out in this work; experiment : ac current was applied to the tendon and dc current was applied to coil wound on the yoke, and voltage induced from search coil wound on yoke (SCY) was measured and experiment : dc current was applied to the tendon and ac current was applied to coil wound on the yoke, and voltage induced from search coil on tendon (SCT) was measured. In case of experiment, voltage induced from SCY was changed below 200MPa tensile stress but the voltage was not increased above 200 MPa. In case of experiment, voltage induced from SCT was decreased up to 1.5 GPa linearly. We expect that experiment could be applied to the non-destructive testing of tensile stress measurement of tendon.