加楔块超声相控阵的聚焦特性测试

ASTM E 2491—2008为相控阵设备的测试提供了指导性规定。根据该标准,在安装楔块的情况下测试相控阵系统的聚焦能力,确定激发晶片数、聚焦深度以及偏转角度对相控阵系统聚焦能力的影响。试验采用标准中规定的试块,试验激发的晶片数为8个、16个、32个,聚焦深度为10,50,100,150,200mm,声束偏转角度为35°,45°,60°,70°。通过试验发现加装楔块后,大部分的近场区都在楔块中,工件中的近场区很小。角度越小,工件中的近场区越大,随着角度的增大,聚焦能力变弱。随着聚焦晶片数量的增加,聚焦能力增强。随着聚焦深度的增加,焦点尺寸增大。越接近楔块物理主声束,分辨率越好。

Test of Focusing Performance of Phased Array Ultrasonic System with Wedge

ASTM E2491—2008 provides the standard guide for evaluating performance characteristics of phased array ultrasonic testing instruments and systems.In this paper,we use the phased array technology to measure the beam focusing capability of phased array ultrasonic with wedge according with ASTM E2491—2008 so that we can identify the causes and effects of focusing capability in the factors such as the numbers of elements,the focal depth and the scanning angle.In the test,the block designed in ASTM E2491—2008 has been used,the elements used are 8,16 and 32,and the focal depths used are 10,50,100,150 and 200 mm,and the scanning angles are 35°,45°,60°and 70°.Through the test,we can find that a large proportion of the near field is in the wedge and only a small proportion of the near field is in the block.The smaller the scanning angle is,the larger the near field in the block is.And if the scanning angle increases,the focusing capability becomes weaker.The focusing capability is intensified when the number of the elements increases.The focal depth increases,the focal spot size increases,too.The resolution of the system will be better if the scanning angle is close to the physical angle of the wedge.