Characterization of small defects using ultrasonic arrays: a scattering coefficient matrix approach
The ultrasonic scattering coefficient matrix defines the far field scattering behaviour of a defect as a function of incident and scattering angles. An ultrasonic array with a large aperture can then be used to interrogate a defect over a range of angles and hence extract parts of this matrix. Experimental results are presented using a commercial 64-element, 5-MHz array on two aluminium test samples that contain a number of simulated defects including machined slots and side-drilled circular holes. A sub-array approach is used in which a group of 8 elements are excited in order interrogate the defect from a given angle as well as providing spatial discrimination. In this way a neighbouring circular hole and slot can be spatially resolved and clearly distinguished by their different scattering coefficients over a range of incident angles and scattering angles. Using signals reflected from a known-size side-drilled circular hole as the reference, scattering coefficients of a defect can be normalized. These measured scattering coefficients show a good agreement with scattering coefficients predicted from finite element modelling. For example, the orientations of defects directly below the array are extracted to an accuracy of a few degrees and their lengths were determined with an error of ±10%.
Ultrasonic arrays scattering coefficient defect characterization finiteelement analysis
Jie Zhang Bruce W. Drinkwater Paul D. Wilcox
Department of Mechanical Engineering, University Walk, University of Bristol, Bristol BS8 1TR, UK
国际会议
第十七届世界无损检测会议(17th World Conference on Nondestructive Testing)
上海
英文
667-674
2008-10-25（万方平台首次上网日期，不代表论文的发表时间）