Determination of fiber volume fraction in a cured laminate

Abstract

Propagation of ultrasonic wave in Carbon Fiber Reinforced Polymer (CFRP) is greatly influenced by the material’s matrix, resins and fiber volume ratio. Laser ultrasonic broadband spectral technique has been demonstrated for porosity and fiber volume ratio extraction on unidirection aligned CFRP laminates. Porosity in the matrix materials can be calculated by longitudinal wave attenuation and accurate fiber volume ratio can be derived by combined velocity through the high strength carbon fiber and the matrix material with further consideration of porosity effects. The results have been benchmarked by pulse-echo ultrasonic tests, gas pycnometer and thermal gravimetric analysis (TGA). The potentials and advantages of the laser ultrasonic technique as a non-destructive evaluation method for CFRP carbon fiber volume fraction evaluation were demonstrated.

Surface defect identification based on broadband laser-generated Rayleigh wave with wavenumber filtering

“…methods that have the advantages of fast detection, high accuracy and no damage to object [4,5]. Laser ultrasonic (LU), a contactless, couplant-free, high spatial resolution and nondestructive detection method, has emerged as a novel development direction in recent years, with enormous potential in the detection of surface defects in mechanical components [6,7]. The object irradiated by laser can generate broadband and multi-mode ultrasonic waves, in which the Rayleigh wave mainly propagates along the surface with large energy, thus it is suitable for surface defect detection [8,9].…”