【摘要】 钢绞线中的腐蚀、开裂等损伤,会直接威胁到矿山提升系统的整体安全。为了对钢绞线进行缺陷的定位识别和量化分析,研究了纵向导波在钢绞线中的传播特性。首先通过理论计算得到了螺旋杆中纵向导波的群速度频散曲线及衰减曲线,其次考虑了频率和周期数的变化对导波信号的影响,在无缺陷的钢绞线、单根钢丝和不同缺陷的外围螺旋钢丝中,分别进行了20～100 kHz频率的纵向导波数值模拟。模拟结果表明:纵向导波在钢绞线中传播的群速度随着频率的增大而逐渐减小,纵向导波信号的衰减随着频率的增大逐渐增大,与理论值吻合较好;在单根钢丝中激励纵向导波时,导波只在其内传播,其余钢丝不受影响;使用20～100 kHz 5周期的纵向导波可实现钢绞线缺陷定位,对于靠近钢绞线端面的缺陷,通过降低激发波周期数可达到检测目的;激发波频率一定时,缺陷长度、宽度和深度的增加都使得损伤指数增大,并且呈线性关系,随着激发波频率的增加,损伤指数逐渐增大,说明了高频率导波信号对缺陷更为敏感,激发波频率为60 kHz时最有利于钢绞线缺陷的检测。更多还原

【Abstract】 The safety of mine hoisting system will be directly threatened by corrosion, cracking and other damages in steel strands. Propagation characteristics of longitudinal guided waves in seven steel strands were investigated to identify and quantify the defects in steel strands. Firstly, the group velocity dispersion curves and attenuation curves of longitudinal guided wave in helical rod were obtained by theoretical calculation. Secondly, regard to the influence of frequency and cycle number on guided wave, the numerical simulation of longitudinal guided wave at 20～100 kHz was carried out in defect-free steel strands, single wire and peripheral helical wire with different defects. The results show that the group velocity of longitudinal guided wave propagating in steel strands decreases with the growth of frequency. And the attenuation of longitudinal guided wave becomes higher as the frequency is increasing, which are in good agreement with the theoretical value. The longitudinal guided wave propagates only in single wire when exciting a single wire, and the rest of the steel strands are not affected. Defects location of steel strands can be achieved by using longitudinal guided waves of 20 ～100 kHz 5 cycles. For the defect near the end of strand, the detection purpose can be come true by reducing the excitation wave cycle number. When the frequency of excitation wave is constant, the increase of defect length, width and depth makes the damage index increase linearly. With the growth of excitation wave frequency, the damage index increases gradually, which shows that the high frequency guided wave is more sensitive to the defect. It is found that the defect detection in steel strands has great advantages when the frequency of excitation wave is 60 kHz.更多还原