Comprehensive evaluation of CFRP laminates using NDT methods for aircraft applications

Abstract

The evaluation of carbon fiber reinforced polymers (CFRP) laminates during and after the Mode I test was successfully conducted, integrating non-destructive testing of acoustic emission (AE) and ultrasound scanning. Two different specimens [+45°/-45°/0°]2S and [0°/+45°/-45°]2S were used to detect the effects of stacking sequences of the laminates. Results indicated that applying AE sensors to the specimens slightly affect to the laminate performance. Thus, the laminates are validated and showed that for [+45°/-45°/0°]2S laminates, the system can withstand load and increase the displacement at break more than twice of [0°/+45°/-45°]2S laminates. Moreover, the ultrasound scanning showed that the crack trace is visible. [+45°/-45°/0°]2S laminates have smaller crack around 24 mm compared to [0°/+45°/-45°]2S laminates with 30 mm. Image analysis revealed that after specimen are forced to open, the [+45°/-45°/0°]2S laminates can prevent long crack compared to [0°/+45°/-45°]2S laminates. The double cantilever beam (DCB) test, employing various stacking sequences, demonstrated excellent examination results using non-destructive testing. Theoretical calculations regarding residual thermal expansion due to different coefficients of thermal expansion also revealed a slight impact of varying manufacturing temperatures on the laminates. These findings offer valuable insights for detecting, predicting, and preventing specimen failures in aircraft and aerospace structures without resorting to destructive examinations, facilitating appropriate preventive maintenance.