| Traditional testing techniques are mostly relying on the deformation of the steel structural members to measure stress, but how we measure the stress of the structures that have completed deformation and not fixed sensors? Based on the theory of electromagnetism and the mechanics foundation, we have proposed steel structural stress magnetotactic type electromagnetism experimentally studied.Consider using a more advanced method to measure the stress under the condition of not to damage the structure. Previous research has shown that there exist correlations between stress and induction electromotive force. Based on the theory of electromagnetism,mechanics theory,the principle of electromagnetic induction Faraday, and in the previous experiments research of stress and the induction electromotive force, tries to establish a new steel structure stress testing system, namely magnetotactic type test system. This test method greatly increases testing signals, and increases the SNR, thereby reducing the interference signals.In practical engineering, steel specimen is directly connected with the earth, so we will directly connect samples with the earth, so that the test signal is mixed with ground-signal interference. Take the steel bar grid (circular pipe), be grounded at both ends, introduce ground interference signal, and use magnetic induction test experimental technologies to measure stress. Use loading equipment and the magnetic induction coil sensor, input AC coil in the access, and test magnetic induction electromotive force in the test coil. Obtain the stress, strain and magnetic induction electromotive force changes; induce the relationship expression between stress, strain and magnetic induction electromotive force; use least-square method to deduce the formula of the stress. To-noise ratio analysis of the useful signal interference signals.The experimental results show that:magnetic induction electromotive force gradually decreases with the rising of the compressive stress level, broadly in line with the linear decreasing trend in the law; magnetic induction electromotive force and the strain also have a very good linear relationship. With the rising of the strain, magnetic induction electromotive force gradually decreases. The analysis of signal to noise ratio shows that this test method greatly increases testing signals, and the useful signal is much larger than the grounding interference signals. The influence of the grounding interference signals on experimental data is very small, can be ignored. |
