Meso Scale Modelling of geometry and mechanical properties of an - PowerPoint PPT Presentation

Meso Scale Modelling of geometry and mechanical properties of an interlock reinforced composite Guillaume PERIE Stepan LOMOV Ignaas VERPOEST (MTM KULeuven) David MARSAL (SNECMA)

Geometrical and mechanical modelling of 3D Interlock Fabrics Introduction  Snecma Fan blade Project  Carbon / epoxy composite, 3D reinforcement, RTM process  3D = Better resistance to impact and fatigue  The fan blade  1m long, complex shape  Thickness, Vf and Weave pattern change along the length of the blade 07/04/2009 2nd World conference on 3D fabrics 2

Geometrical and mechanical modelling of 3D Interlock Fabrics Snecma 3D interlock Fabric  3D angle Interlock :  Several weft layers linkes by warp yarns  Shifted weft layers  Thick Fabrics  Parameters of the fabric: Impossible to perform mechanical  Weave pattern tests on all configurations  Spacing between yarns Need of a modeling tool  Type of yarns  Fiber volume fraction WiseTex + TexComp  Shear angle 07/04/2009 2nd World conference on 3D fabrics 3

Geometrical and mechanical modelling of 3D Interlock Fabrics Objectives :  Geometrical modelling of Interlock fabrics :  Modification of WiseTex  Input data : compression behavior of carbon yarns  Validation of the models with image analysis on samples  Mechanical modelling of Interlock fabrics :  Calculation of static mechanical properties  producing database of mechanical properties  Damage modelling ? 07/04/2009 2nd World conference on 3D fabrics 4

Geometrical and mechanical modelling of 3D Interlock Fabrics WiseTex : Modeling of internal geometry of relaxed & deformed textiles  Model a RVE (Representative Volume Element) using the minimum energy principle, calculating the equilibrium of yarn interactions  Covers a wide range of textile structures (2D, 3D, Braided, Knitted, Laminates, non crimp) 07/04/2009 2nd World conference on 3D fabrics 5

Geometrical and mechanical modelling of 3D Interlock Fabrics WiseTex Modifications 1. « Missing Wefts »  Possibility to remove weft yarns In order to model shifted weft layers  Modification of the mathematical coding of the weave pattern with negative values 1 2 3 level 0   1 0 1 2 warp 1   1 layer 1 2 3 4 2 1 0 1   level 1 warp 2   1 2 1 0 warp 3   layer 2 warp 4   0 1 2 1 4 level 2 WiseTex modified WiseTex 07/04/2009 2nd World conference on 3D fabrics 6

Geometrical and mechanical modelling of 3D Interlock Fabrics WiseTex Modifications 2. Modification of interaction algorithm between warp and weft  Different definitions of bending intervals for calculation of bending energy N ° 1 N ° 2 N ° 3 Interval n ° 7 Interval n ° 7 Interval n ° 2 Interval n ° 2 Interval n ° 3 Interval n ° 3 Interval n ° 5 Interval n ° 5 • Interpenetrations between • Interpenetrations between • Good modelisation of undulation yarns yarns of yarns for warp and weft • No crimp on weft yarns • Bad contact zones between • reduced interpenetration • Low Vf warp and weft 07/04/2009 2nd World conference on 3D fabrics 7

Geometrical and mechanical modelling of 3D Interlock Fabrics Input Data : Compression behaviour of carbon yarns  Critical data for prediction of deformation of the fabric  Standard tests (Kawabata) not designed for heavy yarns F max = 10N and no measurment of yarn width  Compression set up developed in LPMT (Laboratoire de Physique et Mecanique des Textiles, Mulhouse, France)  First designed for polymer monofilaments  F max = 1.5 kN  Compression between glass plates = width measurement G. Stamoulis , Ch. Wagner-Kocher and M. Renner An experimental technique to study the transverse mechanical behaviour of polymer monofilaments ,vExperimental Techniques, vol.29, issue 4, 2005 07/04/2009 2nd World conference on 3D fabrics 8

Geometrical and mechanical modelling of 3D Interlock Fabrics Input Data : Compression behaviour of carbon yarns  Matlab routine developed to analyse automaticaly pictures and measurements  Greyscale to binary image  Correction of angle of the yarn axis  Measurment of width on each pixel row and averaging  Synchronization of the image with force and thickness 07/04/2009 2nd World conference on 3D fabrics 9

Geometrical and mechanical modelling of 3D Interlock Fabrics Input Data : Compression behaviour of carbon yarns Force kN 0.01 0.025 0.05 0.1 0.15 0.2 0.3 0.4 0.5 0.6 0.7 0.9 1.1 1.3 1.48 0.68 0.70 0.72 0.74 0.75 0.76 0.78 0.79 0.80 0.81 0.81 0.82 0.83 0.84 0.85 Mean Std 0.53 0.52 0.50 0.49 0.48 0.47 0.46 0.46 0.46 0.45 0.45 0.45 0.45 0.45 0.45 15.10 14.39 13.60 12.88 12.47 12.10 11.69 11.42 11.20 11.06 10.92 10.77 10.58 10.47 10.39 CV % Normalized Width measurements made on 20 samples Force kN 0.01 0.025 0.05 0.1 0.15 0.2 0.3 0.4 0.5 0.6 0.7 0.9 1.1 1.3 1.48 Mean 0.82 0.70 0.62 0.54 0.50 0.47 0.44 0.42 0.40 0.39 0.38 0.36 0.35 0.34 0.33 Std 0.10 0.07 0.06 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 CV % 10.70 9.48 8.76 8.08 7.83 7.59 7.39 7.27 7.18 7.19 7.11 7.04 7.04 6.99 6.94 Normalized Thickness measurements made on 20 samples 07/04/2009 2nd World conference on 3D fabrics 10

Geometrical and mechanical modelling of 3D Interlock Fabrics Input Data : Compression behaviour of carbon yarns  Initial thickness d10 and width d20 :  It is not possible to measure accurately d10 and d20, as the yarn begins to flatten before the measurments starts (when the load cell mesure 0.01 kN  D10 depends a lot on how the yarn is fixed on the glass plate by the operator (different tension and torsion of the yarn)  Deviation between samples in the same serie of tests but also between different series of test : Slope of the curves is similar for every test but curves look shifted up or down which shows a strong dependency on the initial dimensions of the yarns  A proposed solution would be to add tension to the yarn during the compression test A modification of the set up is needed to introduce tension 07/04/2009 2nd World conference on 3D fabrics 11

Geometrical and mechanical modelling of 3D Interlock Fabrics Input Data : Compression behaviour of carbon yarns d1 d2 Yarns compresion 70 65  Average behaviour = WiseTex Input: 60  Improvment in the prediction of the fabric 55 compression 50 Vf % 45 Specimen  40 WiseTex Overestimation due to interpenetration of 35 yarns in WiseTex 30 In the fabric widening of one yarns is 25 constrained by the other yarns 20 Pressure • Need to make tests with side boundaries Fabric Compresion 07/04/2009 2nd World conference on 3D fabrics 12

Geometrical and mechanical modelling of 3D Interlock Fabrics Validation of models with image analysis 1. Transverse Yarns  Filtering on grey scale levels to isolate the yarns and clean the image  Manual separation of contours in Photoshop  Measurments made with image analysis softwares Measurements :  Spacing between yarns  Vf inside yarns  Orientation of cross sections 07/04/2009 2nd World conference on 3D fabrics 13

Geometrical and mechanical modelling of 3D Interlock Fabrics Validation of models with image analysis 2. Longitudinal yarns  Filtering on grey scale levels to isolate the yarns and clean the image  Manual separation of contours in Photoshop  Matlab routines to calculate crimp and orientation of the yarn In Matlab :  Isolation of contours and center line for each yarn  Smoothing of lines using cubic smoothing splines, in order to avoid pixel effect  Measurement of the length of the spline, and orientation of spline at different points 07/04/2009 2nd World conference on 3D fabrics 14

Geometrical and mechanical modelling of 3D Interlock Fabrics Image analysis results Warp Weft Sample WiseTex Model Conclusion: Warp d1 1 0.89  Yarns are flatenning too much Warp d2 1 1.12  Crimp is overestimated due to local Warp Vf % 77.1 70 changes of curvature on the models Warp Crimp % 1.17 1.5  Crimp is not enough accurate : Weft d1 1 0.87 Need to compare histograms of yarns Weft d2 1 1.08 orientation for better characterization Weft Vf % 69.6 63.9 of the fabric. Weft crimp % 1.01 1.2 FabricThickness 1 1.02 Normalized measurments 07/04/2009 2nd World conference on 3D fabrics 15

Geometrical and mechanical modelling of 3D Interlock Fabrics Calculation of mechanical properties  Tex comp routines are used to calculate homogenized mechanical properties of the final composites:  Inputs : WiseTex model for reinforcement and matrix properties  Calculation of mechanical properties by method of inclusions with different calculation schemes implemented (Mori-Tanaka, Iso-Strain..)  Results are compared with measurements made by UTC (Université de Technologie de Compiegne)  Implementation of a tool to produce databases of material  Unique interface linking WiseTex and TexComp  Automatic Production of several WiseTex models based on a range of weaving parameters specified by the user and calculation of mechanical properties with export to excel file. 07/04/2009 2nd World conference on 3D fabrics 16