Abstract
The consolidation of uncured material is an important factor in the design and manufacture of thick laminated composite structures since it is a key driver for part quality and the formation of defects. A new modelling approach and its implementation is presented here. The constitutive relation, based on kinematic enrichment, has been derived from the orientation and volume of the micro-constituents of the material, their respective constitutive laws and the orientation of the interfaces between them. It is applicable for any layered structures, in particular those made of soft anisotropic materials. The proposed method has been implemented into a commercial Finite Element (FE) software via a user material. Its ability to predict wrinkles during the manufacture of laminated composites demonstrates its performance as a design tool, as this provides a challenging test case for any numerical platform.
Highlights
The macroscale mechanical properties of materials are intimately linked to the way their micro-structure responds to loading and the interaction between different phases within the material
A number of methods aiming at amending the classical continuum theory to include a length characteristic of the material inner structure have been proposed. These methods include nonlocal [7] and gradient theories [8]. These have mainly been used to predict failure, recent work has shown the relevance of these methods to model the influence of microstructural mechanisms in the simulation of the deformation of technical textiles [9] and 3D woven fabrics [10] and to model how the deformation of each individual layer affects the formation of out-of-plane wrinkles during the manufacture of laminated composites [11]
To allow proper regularisation, the spatial discretisation needs to be refined enough. These methods require some refinement of the continuum mechanics theory that involve either the use of additional degrees of freedom [11] or the extra computation of gradient [9,10] or non-local terms
Summary
The macroscale mechanical properties of materials are intimately linked to the way their micro-structure responds to loading and the interaction between different phases within the material. For classical homogenisation, the RVE needs to be at least 1 order of magnitude smaller than the size of the macro-domain but that this requirement becomes less stringent as the homogenisation order increases As they require to run multiple analyses for the different scales considered, multi-scale methods need a lot of memory and are CPU-intensive. Most of the predictive tools currently available to composites designers have been developed for composite structures only They are based on analytical formulations and plate theories [21] that often assume that the material is elastic and are only applicable to thin parts. It is shown that in comparison to previous work [25,26] where every single ply of the structure were modelled, the approach allows for considerably faster run time, with minimal compromise in accuracy
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