【作者】 牛峥；

【导师】 杨正华；

【作者基本信息】 长安大学 ， 固体地球物理， 2009， 硕士

【摘要】 本文首先对超声波检测的发展做了一个较全面的论述,并介绍了超声波检测基本原理以及超声波在介质中的传播特点。用物理实验方法对超声波无损检测的准确性进行了探讨,通过数据分析得到了以声时为主并以震幅和频率作为辅助手段可以比较好的判断和分析混凝土特性的结论。介绍了统计学方法、PSD判据法在作为缺陷判定方法时的使用方法,根据缺陷性质、体积大小与PSD判据的关系,建立了缺陷为夹层、空洞、以及蜂窝或其它介质填充等几种PSD临界判定表达式,并根据各测点实测PSD判据与PSD临界值进行比较来判定缺陷。通过比较统计学方法和PSD方法对于缺陷大小不同的两种物理模型的检测结果。提出使用多因素判据法(NFP法)综合声时、声幅、频率作为参数对缺陷进行判定时能够提高缺陷检测的精度同时降低误判值。通过对钻孔对测法测定裂缝深度实验模拟及分析,得到使用声幅作为检测裂缝深度判据时,具有较好效果的结论。基于小波变换原理和特点,运用冲击回波法检测裂缝深度,通过对采集到的信号进行小波变换,提取反映裂缝缺陷的有效特征信息。并通过对不含杂质及含杂质两类实验研究结果表明,将小波变换方法应用于裂缝的检测,能够更好的对裂缝进行判别和分析。并将误差率控制在5%以下。最后总结分析了超声波缺陷检测方法中还需进一步研究讨论的问题。更多还原

【Abstract】 This paper discusses ultrasonic wave nondestructive test in details for the first time, then it introduces the basic principles of the ultrasonic test and the features of ultrasonic wave spreading among concrete medium,Validate in the text the accuracy of the concrete ultrasonic wave nondestructive test by way of physical experiments. Through the data analysis, we can estimate and analyze well the sound can be better judged and analysis of concrete properties, amplitude and frequency can be used as supplementary meansof. The text introduced that statistical methods and PSD as the fashion of defect testing. By means of the relation between the nature, degree, ranges of defect and PSD criteria, Set up in the text an expression formula of critical criterion, at the time of several kinds of defects an fault, cavity , and the honeycomb or the cavity clogged by other medium, etc. through critical judging value and relational expression between the sizes of various kinds of defects and criteria value, with the comparison between them and their real calculated value.Though the expression using the data of test judged the defect between the two different model. Then propose using the multi-factor criterion method (NFP) integrated voice, amplitude and frequency as a parameter to determine the defect, acquired good experimental results. Though experimental simulation of bored on the measurement method determination of crack depth. That is better if using amplitude as the criterion for detecting of crack depth.Based on the character of wavelet transform theory, the impact-echo method is used to detect cracks. The collected signal is analyzed by the wavelet transform. The characteristic information of cracks is picked out. The investigation indicates that the application of wavelet analysis to the cracks faults detecting can make the fault character more clear. Though the impurity-free of impurities and containing two types of experimental results show that, wavelet transform theory has been applied to crack detection, and better identification of analysis of crack.. Error rate can be controlled at below 5%.Ultimately, the features and existing problem of ultrasonic wave nondestructive test. Furthermore, talk about the problem that need study more.更多还原