Spatial Evolution of the Thickness Variations over a CFRP Laminated Structure

Abstract

Ply thickness is one of the main drivers of the structural performance of a composite part. For stress analysis calculations (e.g., finite element analysis), composite plies are commonly considered to have a constant thickness compared to the reality (coefficients of variation up to 9 % of the mean ply thickness). Unless this variability is taken into account reliable property predictions cannot be made. A modelling approach of such variations is proposed using parameters obtained from a 16-ply quasi-isotropic CFRP plate cured in an autoclave. A discrete Fourier transform algorithm is used to analyse the frequency response of the observed ply and plate thickness profiles. The model inputs, obtained by a mathematical representation of the ply thickness profiles, permit the generation of a representative stratification considering the spatial continuity of the thickness variations that are in good agreement with the real ply profiles spread over the composite part. A residual deformation FE model of the composite plate is used to illustrate the feasibility of the approach.

Comparative study of ultrasonic techniques for reconstructing the multilayer structure of composites

“…It is important to consider possible variations in the ply thickness because CFRP plies do not have necessarily a uniform thickness. This variation is mainly introduced during the manufacturing cycle due to resin flow effects before the polymerisation in the autoclave [59,60]. Hence, a combination of 3 different ply thickness sequences is applied for the simulated data as follows: (i) a uniform ply thickness of 220 , (ii) a ply thickness sequence of [220 ∕210 ∕230 ] 8 , and (iii) a ply thickness sequence of [220 ∕230 ∕210 ] 8 .…”

Liquid composite molding reproducibility in real-world production of fiber reinforced polymeric composites: a review of challenges and solutions

“…The effects of flow channeling include resin-rich and clustered fiber volumes that lead to structural defect formation as well as deviation from the desired geometrical description (i.e. higher part thickness) [42,43] that may lead to post-processing or scrap. It must be noted that the specific uncertainty category is highly dependent on design features (i.e.…”

Identification and Modelling of the In-Plane Reinforcement Orientation Variations in a CFRP Laminate Produced by Manual Lay-Up

“…These PDF are obtained through the observation, measurement and analysis of the composite part before, during and after its fabrication. The present methodology was first used to assess thickness variations in a laminated composite plate [2]. The evaluation of a second source of variability, variations in the reinforcement orientation, is hereby presented.…”

“…In a previous study [2], a FE model was used to determine the variations in residual strains at the end of the cooling phase during manufacturing a composite plate taking into account variations in the ply thickness.…”