10.15480/882.1502
Leopold, Christian
Christian
Leopold
0000-0003-4791-2931
1150336684
Schütt, Martin
Martin
Schütt
1176546570
Liebig, Wilfried V.
Wilfried V.
Liebig
0000-0003-1855-6237
1068356049
Philipkowski, Timo
Timo
Philipkowski
1174637064
Kürten, Jonas
Jonas
Kürten
Schulte, Karl
Karl
Schulte
0000-0001-6521-0488
1137579242
Fiedler, Bodo
Bodo
Fiedler
0000-0002-2734-1353
120262258
Compression fracture of CFRP laminates containing stress intensifications
MDPI
2017
compression after impact (CAI)
fractography
free-edge
kink-band
open-hole
scaling
scanning electron microscopy (SEM)
stacking sequence
Ingenieurwissenschaften
TUHH Universitätsbibliothek
TUHH Universitätsbibliothek
2018-01-05
2018-01-05
2017-09-05
en
Journal Article
Materials 10(2017),9: 1039
http://tubdok.tub.tuhh.de/handle/11420/1505
urn:nbn:de:gbv:830-88218032
10.15480/882.1502
11420/1505
10.3390/ma10091039
https://creativecommons.org/licenses/by/4.0/
For brittle fracture behaviour of carbon fibre reinforced plastics (CFRP) under compression, several approaches exist, which describe different mechanisms during failure, especially at stress intensifications. The failure process is not only initiated by the buckling fibres, but a shear driven fibre compressive failure beneficiaries or initiates the formation of fibres into a kink-band. Starting from this kink-band further damage can be detected, which leads to the final failure. The subject of this work is an experimental investigation on the influence of ply thickness and stacking sequence in quasi-isotropic CFRP laminates containing stress intensifications under compression loading. Different effects that influence the compression failure and the role the stacking sequence has on damage development and the resulting compressive strength are identified and discussed. The influence of stress intensifications is investigated in detail at a hole in open hole compression (OHC) tests. A proposed interrupted test approach allows identifying the mechanisms of damage initiation and propagation from the free edge of the hole by causing a distinct damage state and examine it at a precise instant of time during fracture process. Compression after impact (CAI) tests are executed in order to compare the OHC results to a different type of stress intensifications. Unnotched compression tests are carried out for comparison as a reference. With this approach, a more detailed description of the failure mechanisms during the sudden compression failure of CFRP is achieved. By microscopic examination of single plies from various specimens, the different effects that influence the compression failure are identified. First damage of fibres occurs always in 0°-ply. Fibre shear failure leads to local microbuckling and the formation and growth of a kink-band as final failure mechanisms. The formation of a kink-band and finally steady state kinking is shifted to higher compressive strains with decreasing ply thickness. Final failure mode in laminates with stress intensification depends on ply thickness. In thick or inner plies, damage initiates as shear failure and fibre buckling into the drilled hole. The kink-band orientation angle is changing with increasing strain. In outer or thin plies shear failure of single fibres is observed as first damage and the kink-band orientation angle is constant until final failure. Decreasing ply thickness increases the unnotched compressive strength. When stress intensifications are present, the position of the 0°-layer is critical for stability under compression and is thus more important than the ply thickness. Central 0°-layers show best results for OHC and CAI strength due to higher bending stiffness and better supporting effect of the adjacent layers.
Deutsche Forschungsgemeinschaft (DFG)
Open Access Publizieren 2016 - 2017 / Technische Universität Hamburg-Harburg
Deutsche Forschungsgemeinschaft (DFG)
FI 688/5-1
Schadenstolerante dünnschichtige (Thin-Ply) Kohlenstofffaser-Kunststoff-Verbunde mit Graphen-verstärktem Matrixsystem
1996-1944
Materials
2017
MDPI