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基于磁記憶檢測的橋鋼箱梁翼緣損傷狀態力磁關系

Stress?magnetization of the state of flange damage to a bridge steel box beam based on magnetic memory detection

  • 摘要: 金屬磁記憶檢測技術由于其能夠快速便捷的對鐵磁性構件的損傷進行識別,且被認為具有識別隱性損傷的能力,而被廣泛研究。為推進金屬磁記憶檢測技術在橋鋼箱梁損傷檢測方面的應用,對橋鋼箱梁進行了靜力受彎試驗,提取其變形最嚴重的上翼緣磁信號分布,建立了損傷區域力與磁信號和磁信號梯度的關系曲線,并提出用磁場梯度指數來表征鋼梁的受力和損傷狀態。結果表明:上翼緣磁信號曲線與應力變化形態正好相反,磁信號曲線在進入塑性后發生反轉變為負值,且隨應力變化的速度增快,可以判斷構件進入塑性狀態,即將發生損傷;磁場梯度曲線在損傷最嚴重的區域出現最大值,且隨著荷載的增大,磁梯度最大值點不斷向鋼梁中間移動,由此可以進行破壞狀態的預警;磁場梯度與應力關系曲線可將構件整個受力過程明顯的區分為初始、屈服、塑性、損傷4個狀態;可以用磁場梯度指數來進行構件受力狀態與損傷狀態的表征。該研究可為金屬磁記憶檢測技術在橋鋼箱梁損傷狀態的定量評估和預警方面的應用提供依據和參考。

     

    Abstract: Metal magnetic memory detection technology has been widely studied because it can identify damage to ferromagnetic components quickly and conveniently, and it is considered to have the ability to identify hidden damage. To promote the application of metal magnetic memory technology in the damage detection of a bridge steel box beam, a static bending test on the steel box beam of the bridge was performed, and the magnetic signal distribution of the upper flange with the most severe deformation was extracted. The quantitative relationship between the stress in the damaged region and magnetic signal or magnetic signal gradient was established, and an approach for characterizing the stress and damage state of the steel beam was proposed using the magnetic field gradient index. The results show that the magnetic signal curve of the upper flange is opposite to that of the stress change form, and the magnetic signal curve reverses to a negative value after entering the plastic state and increases with the stress change speed, so the component can be judged to enter the plastic state and soon be damaged. The maximum value of the magnetic field gradient curve appears in the position with the most severe damage, and with the increase in the load, the maximum value point of the magnetic gradient constantly moves to the middle of the steel beam; thus the early warning of the failure state can be conducted. The relationship curve between the magnetic field gradient and stress can obviously distinguish the entire stress process of the component, which includes four states: initial, yield, plasticity, and damage. The stress state and damage state of components can be characterized using the magnetic field gradient index. This study can provide a reference and basis for the application of metal magnetic memory detection technology in the quantitative assessment and early warning of the damage status of bridge steel box beams.

     

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