相控阵超声检测中的近场和远场选择

Near Field and Far Field Selection in Phased Array Ultrasonic Testing

相控阵超声检测使用多个阵元分别激励,通过干涉效应合成检测声场,故在激发孔径的近场区具有较强的可控性,理论上在近场区的检测效果也更好,这与常规超声优先选用远场区进行定量检测有所不同。针对上述差异,以仿真分析为主要手段,结合实际检测中常用的聚焦法则,对相控阵超声近场聚焦和远场检测的灵敏度、分辨力及定量误差进行了量化分析,总结了近场焦点和远场干涉的选用原则,并对相控阵超声定量检测提出了建议。

For phased array ultrasonic testing,multiple elements are used to synthesize inspecting sound field with timing excitation and reception.Theoretically,this technique has a better inspection capability in near field area because of strong controllability based on interference effect,which is different from conventional ultrasonic testing,where far field area is preferred for quantitative inspection.This paper focused on the above differences by considering the focal law frequently-used in actual inspection and using simulation method to analyze the sound field characteristics of near field and far field area in phased array ultrasonic testing.The detection sensitivity,resolution and quantitative error of near field focusing and far field focusing in phased array ultrasonic testing were analyzed quantitatively.The selection principles of near field focus and far field focus were summarized and some advice for phased array ultrasonic quantitative testing was suggested.