Analysis of cure induced deformation of CFRP U-shaped laminates

The thermochemical and the thermomechanical phenomena that happen during the cure process of a composite material laminate are responsible for the rise of residual stresses and, consequently, for the deformation at the end of the manufacturing process. In this work, the influence of some parameters, such as the laminate thickness, the stacking sequence and the mold radius, on the spring-in angle of a U-shaped laminate was studied exploring a full factorial plan through numerical simulations. Moreover, the influence of the laminate shape on the deformation was investigated. First of all, a numerical model appropriate for cure simulation was introduced and its suitability to simulate the deformation behavior was demonstrated. Using a simulation model instead of running experimental test was important for analyzing the parameters influence without reduce the full factorial plan to a fractional one and without wasting a lot of time and material. As a result, only the stacking sequence influenced the spring-in value, while the effect of the tool radius and laminate thickness was minimal. Finally, a comparison between U-shaped and L-shaped laminates evidenced that the spring-in value was independent of part shape, while this parameter affected the flange warpage.