Analysis of the mechanical performance of composite structures is typically undertaken assuming a perfect fiber alignment and micro-structure. Manufacturing effects like ply waviness are partially covered with a cascade of mechanical properties adaptions propagating the stress justification of a structure from coupon level over elements to full scale analysis and testing accordingly. Robust sizing methods considering the structure “as built”, i.e. including the effect of e.g. ply waviness on mechanical properties and load bearing capacity, can substantially reduce efforts in both subcomponent analysis and initial dimensioning as well as evaluation of deviations occurring during the serial production. A concept of virtual testing will improve the opportunity to define detailed strength allowables for an enhanced damage tolerant design and thus reveals a high cost saving potential.
Aim of this thesis work is to investigate the load bearing behavior of laminates featuring ply waviness in different configurations, i.e. varying position of the waviness through thickness as well as characteristics of the waviness quantified with the amplitude to wave length ratio. An in-house developed continuum damage model is used to track damage initiation and to predict the final failure of the laminate. For this purpose, parametric finite element (FE) models of coupons featuring representative ply waviness configurations and boundary conditions are built up and analyzed. Based on results evaluation of virtual coupon tests, a categorization of ply waviness configurations is elaborated indicating criticality depending on geometrical and load specific characteristics.