Volume 13, Issue 1, 2004

Internal Stresses and Warpage of Thin Composite Parts Manufactured by RTM*

Edu Ruiz, Francois Trochu and Raymond Gauvin

Centre de Recherches Appliquιes Sur les Polymθres (CRASP), Dιpartement de Gιnie Mιcanique, Ιcole Polytechnique de l’Universitι de Montrιal, H3C 3A7, Canada

(Received 7/03; accepted 12/03)

Abstract

Resin transfer moulding (RTM) is a widely used manufacturing technique of composite parts. A proper selection of process parameters is the key to yield successful moulding results and obtain a good part. Among other things, when thermoset resins are processed, the shrinkage that occurs due to the polymerisation reaction further complicates the situation. In this paper, a finite difference analysis is proposed to simulate the effect of thermal and rheological changes during thin plates cooling after processing. Classical Laminate Theory is here implemented to compute composite internal stresses resulting from these thermo-rheological conditions. Laminate stresses are then computed and warpage obtained with the proposed numerical algorithm. Samples of thin plates were moulded combining two glass reinforcement materials. During cooling, after processing plates warpage was recorded and results compared to model predictions. This analysis presents the basis of a further numerical optimisation for thick composite parts.