OPTIMAL LAY-UPS TO MINIMIZE PROCESS-INDUCED DEFORMATIONS IN L-SHAPED CFRP PARTS

This paper presents results concerning the mitigation of process-induced deformations in composite parts. The focus is on combining numerical models based on finite elements and experimental testing to propose specific lay-ups around geometry transition points, such as sharp corners, to minimize process-induced deformations such as spring-in angle and warpage. The numerical model is based on higher-order layer-wise 1D finite elements providing very accurate through-the-thickness distributions of shear and peeling stresses. Such a numerical approach requires a fraction of the computational cost usually needed by 3D finite element models. Evolution of material properties such as degree of cure, viscoelastic moduli, and free strains are characterized using DSC and DMA tests. Accordingly, a cure-hardening instantaneously linear elastic (CHILE) constitutive model is adopted for numerical simulations. Simulation results and proposed optimal lay-ups are validated by fabricating L-shape parts with similar conditions.