Fatigue and ultrasonic testing of epoxy-glass composites

Purpose: The purpose of this paper was to find relationship between the degree of strength degradation caused by fatigue and the changes of ultrasonic wave characteristics such as wave velocity and damping coefficient. Design/methodology/approach: Epoxy-glass composites were subjected to oscillatory bending loadings with constant deflection. During fatigue procedure the force needed to achieve constant deflection was measured. During fatigue tests samples were subjected to ultrasonic tests. Additionally before fatigue test and after 300 000, 850 000 and 1 900 000 cycles parts of samples were subjected to destructive bending test. Findings: A good correlation between velocity of ultrasonic wave propagation and the degree of strength degradation of epoxy-glass composites caused by fatigue was found. Ultrasounds can be applied as effective tool to assessment of fatigue degradation of polymer composites. Research limitations/implications: Achieved results showed that research have to be continued. Fatigue with other loading conditions and for other composite materials is planned. Practical implications: The results of present research can be applied to elaboration of non-destructive method of measurement of the degree of fatigue degradation of polymer composites. Originality/value: Presented correlation between ultrasound wave characteristics and the degree of strength degradation caused by fatigue is original value of this paper.