论文翻译-铝蜂窝结构腐蚀的脉冲涡流检测研究.doc

Non-destructive testing of low-energy impact in CFRP laminates and interior defects in honeycomb sandwich using scanning pulsed eddy current Introduction In recent decades, there has been an increasing interest in the use of composite materials and structure, like carbon fibre reinforced plastics (CFRP) and sandwich honeycomb structure in many industrial fields, because of the low weight and improved mechanical properties compared with metals. On one hand, random porosity or undesirable material may appear in composite structures during manufacturing process. On the other hand, outside impacts may result in delamination or disbonding when structures are in service. These undesirable inclusions or defects affect the structure and its mechanical properties. In order to check the integrity of the composite structures, these defects have to be detected and evaluated after manufacturing and monitored during in-service operation. To accomplish this, non-destructive testing (NDT)techniques are investigated, such as ultrasonic testing, X-ray, eddy current (EC), microwave, electrical resistivity measurement, acoustic emission, flash thermography, and shearography. Eddy current, widely used for detecting defects in metallic components, can be used in detection of conductive composite material, like CFRP and metal–matrix composites. EC testing offers a number of advantages compared to other NDT techniques: it enables detection of surface and subsurface damage in contrast to dye penetrant inspection; it can be applied to non-magnetic metallic items in contrast to magnetic flux leakage; it does not require an acoustic couplant as is the case for ultrasonic inspection,and it is more economical, easily applied, and less hazardous than radiography. Pulsed eddy current (PEC) technique is an important advance over other EC methods, which has been proved as an effective tool for flaw detection and corrosion detection in metals. In previous works, various features are selected and us