摘要
针对混凝土超声波层析成像检测中常用的频率,研究了超声波场的指向性及近场区声压的轴向变化规律,其结果表明:对频率为20kHz超声波场,可近似认为声压在各个方向上是均匀的;对40~60kHz的频率段,在进行混凝土超声波衰减成像时,应根据观测方向角的变化对所测振幅值进行方向性校正,并给出了校正计算方法;当频率大于100kHz时,难于进行衰减成像;由近场区轴压图可知:对混凝土超声波成像检测中所用的频率段,观测点均位于声场较稳定的远场区.
The directivity of ultrasonic field and the axial regularity change of near-field acoustic pressure are studied according to the usual frequency that is used in the detection of ultrasonic attenuation coefficient tomography in concrete.l It shows that the acoustic pressure to each direction can be considered as approximately equal that the frequency of the ultrasonic field is 20kHz.And to the frequency that is 40~60kHz,the amplitude value should be adjusted according to the change of the measure direction.The adjustment method is also presented in this paper.When the frequency is over 100kHz,it is difficult to have a ultrasonic attenuation tomography.To the frequency use in the ultrasonic attenuation tomography in concrete,the observation point is in far field that the acoustic pressure is stable.
出处
《工业建筑》
CSCD
北大核心
2007年第z1期1020-1022,1037,共4页
Industrial Construction
基金
江门市科技计划项目资助(20052007)
关键词
超声波
混凝土
衰减成像
ultrasonic concrete attenuation tomography