 | Kuntz J.G. A methodology for characterization and assessment of carbon fibre non-crimp fabric textiles / Deutsches Zentrum für Luft- und Raumfahrt, Institut für Faserverbundleichtbau und Adaptronik, Braunschweig. - Köln: DLR, 2016. - xxvi, 236 S.: Ill. - (Forschungsberich; 2016-58). - Bibliogr.: p.207-216. - ISSN 1434-8454
Шифр: (Pr 1120/2016-58) 02
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Abstract ....................................................... II
Acknowledgements ............................................... IV
List of figures ................................................ IX
List of tables ................................................ XIV
List of symbols and abbreviations .............................. XV
1 Introduction ............................................... 1
2 Basics and literature review ............................... 4
2.1 NCF textiles ............................................... 4
2.2 Processing of NCF textiles with liquid resin composite
moulding ................................................... 8
2.3 Textile evaluation systems for garment textiles ........... 11
2.4 Evaluation/assessment of textile drapeability and test
methods ................................................... 14
2.4.1 On drape simulation ................................ 17
2.4.2 Test methods for biaxial NCF ....................... 18
2.4.3 Test methods for tri- and quadraxial NCF ........... 26
2.5 Compaction characteristics of dry textiles ................ 31
2.6 Evaluation of resin infusion characteristics .............. 35
2.7 Evaluation/assessment of textile quality and test
methods ................................................... 37
2.7.1 Macroscopic defects ................................ 37
2.7.2 Mesoscopic structures .............................. 38
2.7.2.1 Knitting yarn punctures ........................ 39
2.7.2.2 Out-of-plane ply waviness ...................... 40
2.7.2.3 In-plane fibre orientation ..................... 44
2.7.3 Microscopic structures ............................. 49
2.8 Mechanical property calculation models .................... 51
2.8.1 Influence of in-plane and out-of-plane fibre
misalignment ....................................... 52
2.8.2 Influence of knitting yarn punctures ............... 53
3 Methodology for NCF textile characterization and
assessment ................................................ 57
3.1 Methodology overview ...................................... 57
3.1.1 Parameters related to processing behaviour ......... 59
3.1.2 Parameters related to textile quality and
mechanical properties .............................. 61
3.1.3 Prerequisites and other remarks .................... 62
3.2 Applied test and evaluation methods ....................... 64
3.2.1 Bias extension test ................................ 64
3.2.1.1 Test set-up and procedure ...................... 65
3.2.1.2 Data analysis and theoretical background /
modelling ...................................... 67
3.2.1.2.1 Initial data transformations and image
analysis ................................... 67
3.2.1.2.2 Idealized specimen behaviour:
predefinitions ............................. 71
3.2.1.2.3 Idealized specimen behaviour: modelling/
equations .................................. 72
3.2.1.2.4 Material parameter derivation .............. 74
3.2.1.3 Result evaluation .............................. 81
3.2.2 Large area picture frame test ...................... 83
3.2.2.1 Test set-up and procedure ...................... 83
3.2.2.1.1 Specimen preparation ....................... 85
3.2.2.1.2 Mounting specimen in LAPF .................. 86
3.2.2.1.3 LAPF shearing process ...................... 89
3.2.2.2 Data analysis and theoretical background /
modelling ...................................... 90
3.2.2.2.1 Specimen ply geometries .................... 90
3.2.2.2.2 Areal weight changes ....................... 93
3.2.2.2.3 Buckling effects in compressed ply ......... 94
3.2.2.3 Result evaluation .............................. 99
3.2.3 Bulk factor test method ........................... 100
3.2.3.1 Test set-up and procedure ..................... 100
3.2.3.1.1 Textile stacking and weighing ............. 100
3.2.3.1.2 Test preparation .......................... 101
3.2.3.1.3 Test description .......................... 101
3.2.3.2 Data analysis and theoretical background /
modelling ..................................... 103
3.2.3.2.1 Carbon fibre areal weight calculation ..... 103
3.2.3.2.2 Nominal stack thickness ................... 104
3.2.3.2.3 Bulk factor ............................... 104
3.2.3.3 Result evaluation ............................. 105
3.2.4 In-plane resin infusion test ...................... 107
3.2.4.1 Test set-up and procedure ..................... 107
3.2.4.2 Result evaluation ............................. 111
3.2.4.3 Evaluation options for different background
contexts ...................................... 111
3.2.5 Knitting yarn puncture characterization ........... 112
3.2.5.1 KYP geometry parameters ....................... 112
3.2.5.2 KYP distribution parameters ................... 118
3.2.5.3 Result evaluation ............................. 119
3.2.6 Characterization of in-plane fibre angle
deviations ........................................ 120
3.2.6.1 Test set-up and procedure ..................... 120
3.2.6.2 Data analysis ................................. 122
3.2.6.3 Result evaluation ............................. 124
3.2.7 Waviness measurement .............................. 124
3.2.7.1 Test set-up and procedure ..................... 125
3.2.7.2 Data analysis and theoretical background /
modelling ..................................... 126
3.2.7.3 Result evaluation ............................. 131
3.3 Mechanical property influences and modelling ............. 132
3.3.1 Basic properties .................................. 132
3.3.2 Influence of in-plane fibre orientation
deviations ........................................ 133
3.3.3 Waviness influence ................................ 133
3.3.4 Influence of knitting yarn punctures (KYP) ........ 135
3.3.5 Combined compression strength estimation .......... 136
3.4 Proposal for an assessment procedure ..................... 138
3.4.1 Derivation of measures regarding textile quality
and mechanical properties ......................... 140
3.4.1.1 Measure derivation from direct correlations
between textile parameters and laminate test
results ....................................... 141
3.4.1.2 Measure derivation from laminate mechanical
property estimation or test ................... 143
3.4.2 Derivation of measures regarding processability ... 144
3.4.2.1 Measures related to drapeability .............. 144
3.4.2.2 Measures regarding bulk factor ................ 148
3.4.2.3 Measures related to infusion .................. 149
4 Validation of the methodology and further test
observations ............................................. 151
4.1 Validation of bias extension test method ................. 151
4.1.1 Force to shear angle progressions and
deformation energy ................................ 151
4.1.2 Real/ideal elongation ratio progression ........... 160
4.1.3 Deformed textile quality and deformation
behaviour ......................................... 167
4.1.3.1 Loop fraction progression ..................... 167
4.1.3.2 Comparison to real part drape tests ........... 170
4.1.3.3 Fault and error influence loop fraction ....... 170
4.1.3.4 Sliding distance .............................. 171
4.1.3.5 Fault and error influences d,im(a) ............ 173
4.1.3.6 Findings and conclusions on material
behaviour ..................................... 177
4.2 Validation of large area picture frame test method ....... 182
4.2.1 Explanation approaches for observed tri- and
quadraxial NCF shear behaviour .................... 184
4.3 Validation of bulk factor characterization method ........ 185
4.3.1 Fault and error influences bulk factor ............ 187
4.4 Validation of in-plane resin infusion test method ........ 189
4.5 Textile quality characteristics and mechanical
properties ............................................... 194
4.5.1 Direct correlations of measured parameters and
compression strength .............................. 194
4.5.2 Validation of laminate property estimation ........ 198
5 Summary and Outlook ...................................... 203
Bibliography ............................................. 216
A Appendix ................................................. 217
A.l Drawings and further details on large area picture
frame .................................................... 217
A.2 Lamination theory calculations applied ................... 219
A.3 Example images for textile shear deformation ............. 224
A.4 Bookmark tables with textile parameter overview .......... 234
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