In-situ measurement and numerical simulation of resin pressure during Glass/Epoxy prepreg composite manufacturing

Resin pressure distribution of a curing Glass/Epoxy prepreg lay-up is the key parameter that controls the strength, stiffness and void nucleation of the cured composite part. It is vital to monitor and control the resin movement of curing laminate to optimize its quality in any manufacturing process. In this paper, design of a Fiber Bragg grating (FBG) based device, capable of measuring in-situ resin pressure of a curing lay-up is presented. This device uses the principle of differential pressure in liquids. The device was calibrated using a water column, and a pressure sensitivity of 1.636 × 10−2 MPa−1 was yielded. FBG responds linearly with the rise of hydrostatic pressure in the water column. An excellent agreement was found between experimental and theoretical results. This device was used to monitor the resin pressure in a curing prepreg composite lay-up. The measured liquid resin pressures were also compared to the resin pressure obtained from a coupled multi-physics numerical simulation. The presented sensor is useful for in-situ pressure measurements, especially for high temperature and low or zero bleed curing of composites, for example, out of autoclave curing.