|
|
Using epoxy adhesives to joint fiberglass composite (GFRP) parts is a common practice to build larger components. It is the case of windmill blades, where structural strips are bonded to the blade inner surface, both manufactured with GFRP. Structural resistance of the blade depends on these joints quality, and hence, non destructive evaluation is mandatory to guarantee component life. Non destructive evaluation of GFRP using ultrasound is a challenging task. Microstructure of fiberglass and resin composites introduces dispersive effects on ultrasound waves, which is seen as grain noise and produces high attenuation to ultrasonic signals. The traditional approach to overcome these problems is using low frequency transducers (typically 500 kHz), at the expense of loosing resolution, and hence, the capability to detect small defects or to inspect low thickness components. In this work, results from the inspection of a strip bonded joint of a windmill blade using phased-array are presented. It is demonstrated how this method provides high resolution images at the same time inspection time is greatly reduced.
|
