复合异质结构声发射信号传播特性研究

Investigation of propagation characteristics of acoustic emission waves in composite heterogeneous structures

  • 摘要:
    目的 旨在研究声发射信号对典型复合异质结构中的传播特性。
    方法 首先,基于半解析有限元方法开发频散曲线计算程序,计算声发射波在复合结构板中的群速度频散曲线;然后,采用ABAQUS软件建立复合结构模型,并模拟典型声发射源信号的传播过程,研究声发射信号在复合结构中的频散特性和衰减特性;最后,针对复合异质结构,结合小波变换和模态声发射理论,分析T型复合异质结构中声发射信号的时频特性与模态转换。
    结果 结果表明:声发射信号衰减特性与信号传播距离和传播方向相关,经过异质结构界面时信号会大幅衰减;声发射信号与异质结构相互作用会产生复杂的传播现象,包括T形变换和模态转换等;声发射信号T形变换中反射信号的信号强度最强,跨结构透射和经过90°转角结构透射信号的信号强度相当。
    结论 研究通过使用反射系数和透射系数量化了信号的散射特性,结果可为海洋结构物声发射监测提供理论参考依据。

     

    Abstract:
    Objective This study investigates the impacts of acoustic emission (AE) signals on the propagation characteristics of composite hetero-structures.
    Methods First, the calculation procedure of the dispersion curves is developed on the basis of the semi-analytical finite element method in order to calculate the group velocity dispersion curves of AE waves in composite panels. Next, ABAQUS is used to establish a finite element model and analyze the dispersion and attenuation characteristics of AE signals in the composite structure. Finally, the time-frequency characteristics and mode conversion of AE signals in a T-section composite hetero-structure are analyzed in combination with wavelet transform and modal acoustic emission theory.
    Results The attenuation of AE signals is related to the propagation distance and direction of signals, in which a signal is significantly attenuated when passing through the hetero-structure interface. The interaction between AE signals and the hetero-structure will produce complex propagation phenomena including T-shaped transformation and modal conversion. The signal strength of the reflected signal is strongest in the T-shaped transformation of the AE signal, and the signal strengths of the transmitted signals across the structure and the transmitted signals through the 90° corner of the structure are comparable.
    Conclusion This paper quantifies the scattering characteristics of AE signals using reflection and transmission coefficients, thereby providing theoretical references for the AE monitoring of marine structures.

     

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