Upload
hilary-jenkins
View
229
Download
8
Embed Size (px)
Citation preview
Rome 15 – 17 April 2009
Scarponi Claudio *Pizzinelli Corrado Sebastiano *
Sonia Sánchez-Sáez **Enrique Barbero **
* Sapienza Università di Roma
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre
composite laminates
Second International Conference onInnovative Natural Fibre Composites for Industrial Application
** Universidad Carlos III de Madrid
Introduction: Natural Fibers
2Impact load behaviour of RTM
(Resin Transfer Moulding) hemp fibre composite laminates
Vantages:•Good specific mechanical properties•Low cost, low weight, low tool wear•“Bio-friendly”, non toxic…•Thermal and electrical insulation
Disadvantages:•Properties depend from many factors•Defects and irregularities•Water absorption (swelling and problems…) •Fiber/matrix adhesion…
Natural fibres might be a realistic alternative to glass fibres reinforced composites
Applications and possible market
3Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
• Radome• Interiors (seats, caps, tables…)• Baggage container• Non primary structural applications
in general
Aims of this work
• Investigate the behavior of composites laminates reinforced by hemp fabric, processed by RTM
• Improve the RTM process• determine the effect of damages caused by
low velocity impact loads• Compare the results with literature
4
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
Reinforcement
5
“plain weave” hemp fabric (National Canapificio Linificio-Spa of Verona)
Linear mass density (average) [Tex] 71,7
Pretentioning strength [cN/Tex] 0,5Density (average) [gr/cm3] 1.7Maximum strength (literature) [MPa] 590±150Young Modulus (literature) [GPa] 18 ±4Elongation at break in traction (literature) [%] 4±0,3Specific areal weight [gr/m2] 244Price [euro/ meter2] 12
From previous studies alkalinization with sodium hydroxide NaOH 1% wt did not produce convenient performance increase
Fabric has not been chemically treated
Matrix
6
Epoxy Resin
SR1710
Curing Catalyst
SD8824
SR1710/SD8824
Mix 100ml/28mlViscosity [mPa*s] 20 ºC25 ºC
1300800
86
205120
Density [g/cm³] 20 ºC
1,152 0,942 1.106 *
(*calculated data)
It has been chosen an epoxy resin, because of its excellent mechanical properties and in particular for the resistance to
interlaminar shear
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
RTM & PROCESS
7
The panels fabrication has been performed at the Centro Sviluppo Materiali laboratories, with a Plastech T.T. machine.
COMMAND CONSOLE
OMOGENIZATOR
MOLD
• command console• omogenizator (the
degassing is performed here only for the first panel)
• mold
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
8
Mold & Countermold• 400x400 mm • Electrically heated• The resin, after being aspired from the omogenizator, is degassed • On the mold there are some little holes through which is aspired the resin in
excess
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
9
Injection & polymerization• 0°/90° fabric disposition• Vacuum • Degassing & Resin injection at 0.5 bar• After having wetted half tissue, pressure is increased and kept to 3 bar
Polymerization sequence
1. 6h at room temperature, to reduce risk of reactions2. 24h at 40 º C
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
Hemp-Glass comparison
10Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
2 hemp threads
Glassfiber fabric
zoom
zoom
Panel 1
11
PANEL 1. (12 plies)Resin Inlet
• bad wetting• non uniform
resin distribution
• voids
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
Resin Trap and Improved degassing
12
Degassing; it is visible the typical “foam”The “resin trap” prevents the excess resin flow to go back into the pump
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
Also the maximum pressure has been decreased
Panel 2 & comparison
13
Resin Inlet
PANEL 2. (14 plies)
Resin Inlet
PANEL 1. (12 plies)
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
14
Properties and comparison
PANEL PROPERTIES
Panel 1
Base RTM%
Panel 2
Enhanced RTM
%
Total Weight (g) 880 - 1084,5 -
Fibers weight (g) 367,7 42% 520 48%
Resin weight (g) 512.3 58% 564,5 52%
Area (cm²) 40*33=1320 - 40x40 = 1600 -
Thickness (mm) 5,1 - 5,1 -
Volume (cm³) 673,20 - 816 -
Density (panel) (g/cm³) 1.307 - 1.329 -
V resin (cm³) 463.18 68.8% 510.37 62.5%
V fibers (cm³) 210.02 31.2% 305.73 37.5%
N. of fabric plies 12 _ 14 _
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
Resin Inlet point
Tensile and flexural tests (4PBT)
15Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
Tensile: 5 specimens tested on a Zwick machine at room temperature, with a load cell of 250 kN, following normative ASTM D3039 (D638 for test on resin)
4PBT: 6 specimens tested at room temperature, with a load cell of 200kN, following normative ASTM D790-86.
Tensile test
16
0
10
20
30
40
50
60
70
80
90
100
0,00 0,50 1,00 1,50 2,00
str
ess (
MP
a)
strain %
Tensile test: stress-strain curve
Table 5:
MATERIAL
Max strength
(MPa)
Young Module
E (GPa)
Rupture load
(N)
Strain
(rupture) %
Hemp/Epoxy 93,77±3,22 6,10±0,17 9542,50 1,9±0,2Impact load behaviour of RTM
(Resin Transfer Moulding) hemp fibre composite laminates
Flexural test
17
-600
-500
-400
-300
-200
-100
0
-25-20-15-10-50
Str
ess
(MP
a)
Displacement (mm)
Since the trend is not linear and the slope of the curve decreases, rupture is probably due to shear stresses.
Table 6Flexural Resistance(MPa)
Flexural Modulus(GPa)
Max Load(N)
Average 145±9,4 11,87±1,65 416,33±22,6variation coefficient 6,48 (%) 13,9 (%) 5,43 (%)
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
Impact test
18Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
Square specimens 100x 100 mm have been utilized for the impact test (3 for each energy level) bounded with a clamping (ASTM D5628-96, ASTM D5428-98th).
The hemispherical head impacter has a mass of 3.966 Kg and a diameter of 12.7 mm
Energy level (J)
5 10 15
Speed (m/s)
1.59 2.25 2.75
Impact
19
Force-time curves. With the help of the table is possible to distinguish:
•Incipient damage time•Displacement at this time
ImpactEnergy
[J]
Incipient damage
time(average)
[ms]
Var. Coeff.
(%)
Displ.(average)
[mm]
Var.Coeff.(%)
5 2.02 4.9 2.41 3.6
10 1.15 1.4 2.31 1.3
15 0.97 1.1 2.47 0.95
Impact 2
20
Force-deflection average curves. With the help of the table is possible to distinguish:
•Max displacement•Instant of max displacement
ImpactEnergy
[J]
MaxDispl.[mm]
Var.Coeff.(%)
Max displ. Time [ms]
Max Force
[N]
Var.Coeff.(%)
5 2.79 2.8 3.10 2689 1.910 4.58 2.7 3.64 2989 0.815 6.44 2.8 4.37 2996 4.1
Energies involved
21
absorbedelasticimpact EEE
dispdamageabsorbed EEE
dispdfdmnindentatioelasticimpact EEEEEE
Eabsorbed, is the asymptotic Energy value and represents the energy dissipated in fracture mechanism. It can be divided in two major type of contributions: energy expended to generate the damage (Edamage ) and energy absorbed by the system by various means such as vibrations, heat, anelastic behaviors, etc. (Edisp):
Impact 3
22
Energy-time curve
red Eimpact,
Green E absorbed
black E elastic
0
4
8
12
16
0 2 4 6 8 10 12
En
erg
y(J
)
Time (ms)
Energy History
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
23Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
24Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
25
(Santulli - STUDY OF IMPACT HYSTERESIS CURVES ON E-GLASS REINFORCED POLYPROPYLENE LAMINATES)
HYSTERESIS
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre composite laminates
26
ImpactEnergy
(J)
Energyabsorbed
(J)
Var. coeff. (%)
En. absorbed/impact En.
5 2.76 0.29 0.55210 7.26 0.63 0.72615 11.4 0.01 0.76
ImpactEnergy[J]
A1 [J]
A2[J]
A3[J]
damping ratio
linear stiffness[KN/mm]
Load drop[N]
5Average 2.547 0.211 0.755 0.351 1.175 75VC (%) 2.1 25.3 19.3 20.6 4.7 6.6
10Average 3.409 3.861 2.224 0.837 1.229 153VC (%) 2.6 1.7 1.1 1.4 3.2 6.6
15Average 3.748 7.685 3.020 0.936 1.240 192VC (%) 1.5 1.1 5.1 1.9 1.2 5.5
27
Specimen code Lay-upHand lay-up
Thickness(mm)
Fiber Volume (%)
Density(g/cm3)
H14 14 Hemp 5.1 38 1.33
J10 10 Jute 8,0 52 1.05
V10 10 E-Glass 300 4,00 35 1.55
JV [3V/2J/1V/2J/6V] 5,0 55 1.33
JA-E 300 [4V/2J/1V/2J/4V] 5,0 55 1.32
JB-E 600 [2V/2J/1V/2J/2V] 5,0 53 1.36
JX-E 600 [1V/2J/1V/2J/3V] 5,0 53 1.35
same geometries, impact energy and boundary conditions
Comparison with jute/vynilester hybrids:
Comparison with jute/vynilester hybrids:
Specimen code
Thick-ness(mm)
Fiber Volume (%)
Max contact force 5J impact(KN)
Max contact force 10J impact (KN)
Max contact force 15J impact (KN)
Energy absorbed 5J impact(J)
Energy absorbed 10J impact(J)
Energy absorbed 15J impact(J)
H14 5.1 38 2.69 2.99 2.92 3.00 7.26 11.43J10 8,0 52 2.70 4.10 3.60**V10 4,00 35 3.50 4.70 5.60 4.880 8.480 11.9JV 5,0 55 4.00 6.00 6.70 4.550 7.880 12.45JA-E 300 5,0 55 4.50 5.00 6.20 4.950 8.200 12.1
JB-E 600 5,0 53 4.20 5.60 6.4 4.375 8.880 12.45JX-E 600 5,0 53 4.10 4.90 6.1 4.380 7.890 11.7
V: glass fiber; J: jute fibers H: Hemp fibers **perforation without trepassing
28
Same MASS, geometries, impact energy and boundary conditions
Impact side
29
Impa
ct lo
ad b
ehav
iour
of R
TM(R
esin
Tra
nsfe
r Mou
ldin
g) h
emp
fibre
com
posi
te la
min
ates
5J
10J
15J
Back side
30
Impa
ct lo
ad b
ehav
iour
of R
TM(R
esin
Tra
nsfe
r Mou
ldin
g) h
emp
fibre
com
posi
te la
min
ates 5J
10J
15J
31
BACKLIGHT: 5J impacted specimens (10 x 10 cm)
Digitally sharpened and “inverted”
Original
BACKLIGHT: 10J impacted specimens (10 x 10 cm)
Digitally sharpened and “inverted”
Original
32
Original
Digitally sharpened and “inverted”
BACKLIGHT: 15J impacted specimens (10 x 10 cm)
33
Impact Energy (J) 5 10 15Delaminated area (mm2) 332 863 1380Standard Deviation (mm2) 108 151 161Variation Coefficient (%) 32,45 17,49 11,69
Conclusions and possible future developments
• An RTM system, has been successfully used with hemp fibers.• It has been proven experimentally that process parameters
greatly influence the final product • The process has been improved with a negligible cost impact.
Even if it was not the aim of this paper, further enhancements are possible in order to achieve more improvements such as geometry and number of resin immission holes, pressure-time curves, curing process.
• Hemp/epoxy composites exhibit good impact properties• It is confirmed the hypothesis that it can be possible to start
using for secondary structures hemp as a reinforcement alternative to glass. Further studies are needed also to characterize the internal behavior of the material and residual properties.
34
Acknowledments
• Ing. Fulvio Ferraro of the CSM for the RTM process; (CSM: Centro Sviluppo Materiali s.p.a., via di Castel Romano n. 100, cap 00128 Roma.)
• Ing Teresa Vetere for the resistance tests• Prof. Carlo Santulli
35
Thank you for your attention!
36
Scarponi ClaudioPizzinelli Corrado Sebastiano *
Sonia Sánchez-SáezEnrique Barbero
*Reference author; E-mail: [email protected]
“Sapienza Università di Roma”
Impact load behaviour of RTM(Resin Transfer Moulding) hemp fibre
composite laminates
Dipartimento di Ingegneria Aerospaziale e Astronautica