In situ estimation of through-thickness resin flow using ultrasound

Ultrasonic imaging in the C-scan mode was used to measure the flow rate of an epoxy resin film penetrating through the thickness of a single layer of woven carbon fabric. Assemblies, comprised of a single layer of fabric and film, were vacuum-bagged and ultrasonically scanned in a water tank during impregnation at 70 °C. The permeability of the fabric was calculated using Darcy’s law. The results demonstrated that ultrasonic imaging in the C-scan mode is an effective method of measuring z-direction resin flow through a single layer of fabric. Comparison of ultrasonic and microscopy images yielded consistent results and demonstrated the effectiveness of ultrasonic imaging as an in situ process diagnostic for monitoring through-thickness impregnation and flow rates.