摘要
为了研究自由锚杆中超声导波的衰减规律，分别制作了长度为800mm、900mm、1100mm、1300mm、1500mm、1800衄、2000mm和2500mm的锚杆。采用虚拟综合测试仪、声发射放大系统、R6et直传感探头和计算机，组装了超声导波无损检测系统。利用该系统分别对制作的锚杆进行了系统的导波测试。结果表明：自由锚杆中超声导波振幅呈负指数分布；不同频率的激发导波在测试频率段内（40-100kHz）波包平均振幅的振幅比均在0．7左右，表明频率对导波衰减的影响不大；不同长度锚杆中波包平均振幅的振幅比也在0．7左右，表明锚杆长度对导波衰减的影响也不大；自由锚杆中导波的衰减，除与材料性质有关外，主要来自于设备本身的系统衰减。研究发现，导波振幅比比振幅绝对值更加稳定、可靠，可用来定量地表示导波振幅的衰减情况。
Eight rock bolts, 800 mm, 900 mm, 1100 mm, 1300 mm, 1500 mm, 1800 nun, 2000 mm and 2500 mm in length, respectively, were designed to investigate the attenuation characteristics by using a guided wave non-destructive test system, which included a Handy-scope, an amplifier, two R6ct transducers and a computer. The results demonstrate that amplitudes of ultrasonic guided waves present a nega- tive exponential distribution and the average amplitude ratios of all wave packets are near 0.7 within the range of the tested frequencies （40 - 100 kHz）, which could be interpreted that the frequency of guided waves had little impact on attenuation. All of the average amplitude ratios of wave packets are near 0.7 with various bolt length too, which could be interpreted that the length of rock bolts had little impacts on attenuation in the tested range. It is understood that in addition to the nature of the material, attenuation of ultrasonic guided waves was mainly from setup energy loss in a free rock bolt. This study also suggest that the amplitude ratio is more stable and reliable than absolute amplitude value and it can be used to quantify the guided wave amplitude attenuation.
出处
《西南科技大学学报》
CAS
2009年第4期56-62,共7页
Journal of Southwest University of Science and Technology
基金
科技部重大国际科技合作专项资助(2006DFA21820)
国家科技支撑计划项目资助(2006BAC10B04)
关键词
锚杆
超声导波
无损检测
导波衰减
振幅比
Rock bolt
Ultrasonic guided wave
Non-destructive test
Attenuation
Amplitude ratio
