Investigation on the Shape Distortions of Pultruded Profiles at Different Pulling Speed

摘要

Pultrusion is a continuous technique for manufacturing of polymer composites which combines automation and versatility. The main factors behind the wide application of the process are the enhanced productivity and the remarkable mechanical properties achievable. Nevertheless, the quality of pultruded products dramatically depends on the choice of the process parameters. As a matter of fact, pultrusion presents numerous tunable parameters, such as the temperature of the heating plates or the pulling speed, because most of the polymerization reaction of the resin occurs within the curing-forming die in a short time. Resin shrinkage, thermal contraction and residual internal stresses change the geometry of the profiles after their production. Process related stresses typically result in distortions evolving for months after the process, which can lead to out of geometrical tolerances. The present paper discusses an experimental/numerical investigation of the shape distortions of L-shaped profiles made of epoxy-based resin reinforced with E-glass rovings and unidirectional glass fabrics. The samples were pultruded at three different pulling speeds, namely 200, 400 and 600 mm/min. For each of them, the spring-in angle was periodically measured for the 90 days following production. The results show the dependence of the shape distortions on pulling speed and on time.