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--- team:gdeliege:composite [2015/08/12 08:30] – created geoffrey
+++ team:gdeliege:composite [2016/03/30 15:23] (current) – external edit 127.0.0.1
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-==== Composite materials ====
+===== Composite materials =====
+=== Background ===
 Carbon-Fibre-Reinforced Polymers (CFRP) are now widely used in aerospace industry
@@ Line 8: / Line 10: @@
 (fibre brittle failure, fibre-matrix debonding, matrix ductile failure and delamination)
 that are not easily described at a macroscopic level.
+When I joined the MN2L-group, my first objective was to implement a material model for composite laminates with woven fibre reinforcement in Metafor. This was part of a project in collaboration with Sonaca, LMS-Samtech and the Université Catholique de Louvain, among others.
-My objective was to implement a material model for composite plies with woven fibre
+=== Constitutive laws ===
-reinforcement in Metafor.
-This model is inspired by the meso-model
+This model I implemented is inspired by the meso-model
 proposed by P. Ladevèze and O. Allix [1-2] for unidirectional
 composites as well as the 2D model for woven composites proposed by C. Hochard [3].
 The idea is to describe the laminate as a stack of 3D orthotropic plies separated by 2D interfaces.
-In a direction parallel to the fibres,
+In directions parallel to the fibres,
 the plies are elastic and subject to brittle fracture;
-in shear, an elastoplastic behaviour is assumed and progressive damage is introduced.
+in shear, an elastoplastic behaviour with progressive damage is assumed.
 The 2D interfaces between the plies are elastic with progressive damage.
 Practical information on the
@@ Line 28: / Line 30: @@
 One interesting feature of Ladevèze and Allix's work is that most parameters of the constitutive laws
 can be linked to physical quantities.
-Therefore, these parameters can be identified with suitable experimental tests.
+Therefore, these parameters can be identified with suitable experimental tests. For example, the hardening and damage parameters characterizing the shear behaviour are determined by cyclic loading tests on a  $[(+45^\circ/-45^\circ)_n]_S$  laminate (Fig. 1).
-{{ :team:gdeliege:stiffener2d.png?direct |Finite element simulation (Metafor) of an impacted stiffener made of woven carbon fibre laminate}}
+Complex as they are, these models neglect important phenomena like the viscoplastic behaviour of the resin or the specific damage mechanism under compressive loading. I am currently working on compressive damage of woven fibre laminates. My goal is to introduce in the mesoscopic model a damage evolution law accounting for the microscopic instabilites (microbuckling) generated in a ply under compression.
-== References ==
+{{ :team:gdeliege:comp05.png?500 |}}
+//Figure 1. Cyclic loading of a laminate sample with ply orientation  $[(+45^\circ/-45^\circ)_n]_S$  : comparison between experimental results and Metafor results.//
+{{ :team:gdeliege:stiffener2d.png?direct500 |}}
+//Figure 2. Finite element simulation (Metafor) of an impacted stiffener made of woven carbon fibre laminate//
+{{ :team:gdeliege:comp01.png?direct500 |}}
+//Figure 3. Finite element simulation (Metafor) of an End-Notched Flexure (ENF) test. It consists in a 3-point bending of a sample with an artificial mid-plane delamination. ENF tests are used to determine the mode II interlaminar fracture toughness of laminates.//
+{{ :team:gdeliege:comp04.png |}}
+//Figure 4. Impact simulation : (left) experimental setup for impact testing at [[http://www.uclouvain.be/en-imap.html|UCL-IMAP (Prof. Pardoen)]], (right) finite element model of the impact test; the impactor is represented as a rigid sphere having the same mass and kinetic energy as the experimental impactor.//
+{{ :team:gdeliege:comp03.png |}}
+//Figure 5. Impact simulation with finite elements (Metafor) on a quarter of a plate : maximum of the orthotropic damage variables  $d_{11}$ ,  $d_{22}$  and  $d_{12}$ , ranging from 0 (blue) to 1 (red).//
+=== References ===
 [1] P. Ladevèze, E. Le Dantec. //Damage modelling of the elementary ply for laminated composites.// Composites Science and Technology, Vol. 43, pp. 257-267, 1992 \\
 [2] O. Allix, P. Ladevèze. //Interlaminar interface modeling for the prediction of laminate delamination.// Composite Structures, Vol. 22, pp. 235-242, 1992 \\
 [3] C. Hochard, P.-A. Aubourg, J.-P. Charles. //Modelling of the mechanical behaviour of woven-fabric CFRP laminates up to failure//. Composites Science and Technology, Vol. 61, pp. 221–230, 2001 \\
+\\
+[[team:gdeliege|Back to main page]]