Theoretical and experimental analysis on void formation in epoxy composite laminates

For advanced resin matrix composites, void is a common defect which can seriously deteriorate the properties of composite parts. This paper focused on the void formation models of hygroscopic water and acetone solvent for epoxy matrix composite laminates prepared in hot pressing process. The effects of temperature, applied pressure, lay-up type and environment humidity on the porosity in laminates were investigated experimentally. Kardos void generation model was developed to analyze the initiation of void. It is found that resin pressure and gel temperature in hot pressing process are two key parameters to qualitatively estimate the porosity, and entrapped air must be considered in the void generation model. The theoretically predicted and experimental results were in good agreement for all the studied cases, which to a certain extent demonstrates the good applicability of modified Kardos void generation model. These results are valuable for eliminating void defect, optimizing processing parameter and enhancing the performance of composite parts.