cimcomp poster3 - adam thompson
TRANSCRIPT
Discrete Modelling of NCF Forming Processes
Adam Thompson [email protected] Supervisor: Prof. Stephen Hallett, Dr Jonathan Belnoue
The continuation of this work aims to:• Explore methods ability at capturing deformations induced through multi-layer forming processes• Use the model to further understand and characterise deformation mechanisms, specifically those which occur through the
thickness• Use this model as a benchmark for the development of more computationally efficient models
Future work
A discrete modelling process has been developed to capturelocal and global deformations induced through the preformingstage of non-crimp fabric (NCF) composite manufacture.
Introduction
Unit Cell to Macro-scale Modelling
Mesh for 3D yarn representation with one yarn surface hidden to show cross-section support
Tow Surface
Stitch Yarn
Cross Section Support
The geometry is then extracted from the Digital Element model andtessellated to form a feature or component scale fabric.
At this scale, the individual tows are described by shell elementswhich act as contact surfaces, this enables inter tow interactions tobe simulated.
Cross sectional supports are placed along the length of the tows,prescribed with visco-elastic material properties to simulate cross-section deformation as a shear dominated phenomenon.
Modelling Compaction Processes
Generating Accurate Initial Geometry
The process begins by generating an accurate as manufacturedgeometry of an NCF utilizing the Multi-Chain Digital Elementtechnique. The foundation of this method is the discretization of thetows into multiple 1D element chains, where each element chainhomogenises the behaviour of a bundle of fibres.
By applying tension to the element chain representing the stitchyarn, the fibrous tows are drawn together generating an accurate asmanufactured fabric geometry .
Predicted as manufactured geometry (post tension)
Comparisons with X-ray CT scans show the discrete method to makegood predictions for the compressive deformations experienced inmulti-layer compaction processes, capable of capturing both towspreading and waviness.
Experiment Prediction
Shear strain
Experiment
Prediction
Modelling Forming Processes
CT Observations
Model Prediction
The method also shows good potential for use in formingsimulations when compared to experimental results of atetrahedron forming process.
Initial geometry representation
Planar View of Tetrahedron Forming Results