Optimal finite element modeling of filament wound CFRP tubes

The complexity of fiber patterns within the layers of a Carbon Fiber Reinforced Polymer (CFRP) composite made with the filament winding technique has an active effect on the mechanical properties of the layer and respectively of the whole structure. While the approximation of mechanical properties in classic laminated composites is a relatively well-researched subject, there is a lack of information on filament wound cylindrical composites. Due to its material variability, filament wound CFRPs require certification results through numerical - experimental validation. Thus, in this work, an optimal modeling procedure of filament wound CFRP tubes is presented. The main goal is to acquire the lamina mechanical properties that could reliably be used in further finite element analyses with implications in critical practical applications with linear and nonlinear characteristics. At first, a homogenization method is applied to obtain the nominal values of layer properties. Next, a simple tensile test, conforming to ASTM 3039 standards, was repeatedly carried out using a representative sample of CFRP specimens, measuring experimental strain data. A stochastic state-of-the-art single objective optimization algorithm coupled to a robust finite element analysis solver is employed in order to finely tune the lamina material parameters minimizing the residual between experimental measurements and numerical predictions. Lastly, three tensile-based validation tests of stepwise difficulty and varying layer orientation, thickness, internal diameter, width and loading conditions are carried out, efficiently confirming the reliability of the characterized lamina material properties. Comparison of experimentally measured and optimal model’s numerically predicted strain response time histories in both linear elastic deformations as well as in nonlinear large deformations under progressive failure response strongly supported the efficacy and effectiveness of the proposed methodology.