Advanced Materials – K618X1NM – Nekonvencní materiály

Advanced Materials – K618X1NM – Nekonvenční materiály
Marcel Adorna, Tomáš Doktor, Jan Falta, Nela Fenclová, Tomáš Fíla, Jiří Hos, Petr Koudelka, Daniel Kytýř, Michaela Neuhäuserová, Jan Šleichrt, Jaroslav Valach
Czech Technical University in Prague, Faculty of Transportation Sciences, Department of Mechanics and Materials, Na Florenci 25, 110 00 Prague 1, Czech Republic
Creep Behaviour of Composite Materials
Post Impact Fatigue Damage
Bioinspired Structures
Fibre Orientation Distribution
In this part measurements of creep behaviour of composite with polyphenylene sulphide matrix reinforced by poly-acrylonitrile carbon fibres (C/PPS)
proposed to be used as structural material for jet-engine frame in aerospace
industry are presented.
This study is focused on inspection of extent of damage induced into corrupted material by fatigue loading.
This part of the project is aimed at mechanical testing of trabeculal bone
structure. Detailed description of deformation behaviour of the trabecular
bone may serve for design and optimisation of bone implants or tissue
scaffolds.
The calculation was based on image analysis algorithm applied on image
acquired by scanning electron microscope. A composite with oriented fibres
was selected to be enable calibration of the algorithm by comparison of the
obtained results with FOD declared by the manufacturer.
lever arms
load-cells
x
φ
y
iminor = Df ibre
φ
ψ
imajor
minor
φ = arccos iimajor
Figure : Impact damage performing using drop tester.
heating chamber
specimens
weights
During the life-cycle of the construction various impact damage may be
inflicted during the flight.
Figure : The bone matrix, or framework, is organized into a three-dimensional
latticework of bony processus, called trabeculae, arranged along lines of stress.
z
Figure : C/PPS specimen for SEM scanning (left). Nomenclature of the fibre orientation
angles (right).
The specimen was incrementally loaded with 1 % increment up to total 7 %
deformation.
Figure : Visualization of custom design device for creep measurements.
Creep experimental device
• rigid structural steel frame
• two independent lever arms with ratio 1 : 10
• load cells with loading capacity up to 10 kN
Thermal chamber
• temperature range from −70 ◦C to 350 ◦C
• temperature stability ±2 ◦C
• internal height 485 mm
Measurement system
• digital single-lens reflex camera
• mid-telephoto macro lens objective
• laboratory LED light source
Creep compliance data were also fitted by Findley’s creep law for polymers
assuming steady-state creep behaviour according to formula Jc(t) = b0tb1
Figure : Details of the analysed plane with regions of different ψ and φ angles.
Figure : Experimental device for dynamic loading.
For the life-cycle assessment the specimens were cyclically loaded using
resonant testing machine.
Figure : A special mini loading device was developed to load the sample incrementally
directly in the X-ray devices. Loading force was recorded using 100 N load cell (U9B,
HBM).
Image analysis procedure
• Segmentation
• Binary morphological operations
• Connected component analysis - cross-sections’ characteristics
calculated
• Remaining nested cross-sections excluded from the analysis
In order to acquire geometrically precise model of the internal trabecular
structure custom designed microtomography device was employed.
−5
x 10
measured data 60 deg, 1.5 kN
measured data 90 deg, 1.5 kN
10
measured data 110 deg, 1.5 kN
measured data 130 deg, 1.5 kN
measured data 140 deg, 1.5 kN
8
measured data 140 deg, 2.5 kN
data fit 60 deg, 1.5 kN
6
data fit 90 deg, 1.5 kN
data fit 110 deg, 1.5 kN
data fit 130 deg, 1.5 kN
4
data fit 140 deg, 1.5 kN
data fit 140 deg, 2.5 kN
2
Creep compliance [1/MPa]
12
Figure : Selected detail of the image data in different phases of the image analysis
procedure.
Conclusions: The analysis of the fibre orientation distribution will provide
a base for representative volume element estimation and homogenisation
techniques in the further development.
0
1
10
2
10
3
10
Time [s]
4
10
5
10
Figure : Graph of fits of Findley’s creep model on experimental data.
Conclusions: Experimental results showed good correlation with standard
creep theory for polymers and with Findley’s creep law.
Figure : Custom designed computer controlled profilometery device equipped with
ScanControl LLT2600-25 laser scanner.
To obtain information about damage propagation during the life-cycle a set
of profilometery experiments was performed.
Figure : The irradiation of the sample was performed using microfocus X-ray tube with
high resolution transmission target (XWT 160, X-Ray Worx). Radiograms were acquired
using large (410 × 410 mm X-ray flat panel scintillating detector (XRD 1622,
PerkinElmer Inc.) with effective resolution 2048 × 2048 pixels with 200 µm pitch.
Current Issues
• Control software for Instron 3382
• Control software for microindentor
• Software tool for evaluation of the data from indentation tests
• Influence of nonmechanical loading to the lifetime of the composites
• Assessment of pore size distribution in 3D structures
• Optimisation of microstructure of the artificial tissues
• Design end testing of safety for glider rope
• Educational lab teaching equipments
Figure : Surface reconstruction of the impacted sample based on laser triangulation.
Figure : Detail of the damaged sample in transversal plane obtained by scanning electron
microscope in secondary electron mode.
Conclusions: Laser profilometery is a suitable method for
non-destructive testing and evaluation of surface damage.
Figure : Reconstructed volumetric data (left). Spatially mapped displacement (middle)
and strain (right) fields.
Conclusions: Time-lapse X-ray tomography allows precise volumetric
strain mapping.
Acknowledgements
The research was supported by the Grant Agency of the Czech Technical University in Prague (research project No. SGS12/205/OHK2/3T/16).
Contact
kytyr@fd.cvut.cz
http://www.fd.cvut.cz/projects/k618x1nm