Abstract
Due to considerations for lighter weight, recent years have seen rapidly expanding use of FRP materials in large structures. FRP blades for wind turbines are an example, with blade length of over 30m and maximum blade thickness of over 100mm for lOOOkw class equipment. Thus far, however, there have been no proposals of non-destructive test methods for the quantitative evaluation of the internal state of FRP in materials having thickness of over 50mm. Although ultrasound inspection is often used for thick board FRP, this method does not allow accurate, quantitative detection of internal defects. This paper presents a non-destructive testing method that employs low frequency ultrasound defect detection technology, developed as an inspection technique for the quantitative evaluation of internal defects in thick board FRP material.
