PROCESSING PARAMETERS OPTIMIZATION OF VACUUM-BAGGING PREFORMING IN OVEN CURE FOR INTER-LAMINAR SHEAR STRENGTH (ILSS) IN GLASS/EPOXY COMPOSITE LAMINATE

Abstract

Autoclave had been restricted to immense production expenses and overabundant residual stress. These disadvantages had prompted development on the alternative of out-of-autoclave (OoA) processing. The optimization on vacuum-bagging-only (VBO) pre-forming process in producing high inter-laminar shear strength (ILSS) of composite laminate was proposed. The effects of individual and combined pre-forming parameters of VBO-oven cure processing for the conventional low-cost glass/epoxy composite material towards ILSS of cured laminates were quantified. 20 composite panels were manufactured following the designated parameter combinations based on central composite design in fractional factorial for response surface model. Three factors of vacuum debulk duration, edge breather number of sides and intensifier weight were investigated. For validation, two laminates without additional processing parameters were produced via oven (baseline) and autoclave. ILSS test was conducted based on ASTM D 2344. The interaction between combined parameters was analyzed using analysis of variance (ANOVA). Lowest ILSS was found in laminates where intensifier was absent, while highest ILSS was measured with edge breather, debulk and intensifier at different levels. An optimum combination of 30 minutes debulk, each sides of edge breather and 1kg intensifier were validated to produce laminate with highest ILSS of 38.96 MPa, which was 23.53% higher than baseline laminate.