Ultrasonic Testing of GFRP Laminate Degraded by Hot Water from One Surface

Abstract

Ultrasonic wave is applied to damage evaluation of GFRP laminate degraded by hot water from one surface. GFRP vessels have been used for storage of both acid solution and alkaline solution because of their excellent corrosion resistance. In these days, integrity evaluation of GFRP vessels has attracted much attention as the number of aged vessels increases. Although degradation proceeds gradually from the inner surface of vessels, sensors can only be attached on the outer surface. Then the through-thickness method for damage evaluation is required. In this research, GFRP plates are degraded by hot water from one surface, and through-thickness ultrasonic inspection is conducted to reveal the dependence of ultrasonic characteristics on damage state of the plates. Beside wave attenuation and velocity, characteristics of reflected waveforms from the degraded surface are analyzed. It is found that the envelope of echo from the degraded surface reflects damage propagation in the thickness direction, and it can be used as damage index of GFRP vessels.