Download - PPT Defence
Effect of Resin/Hardener Ratio On The Dynamic Fracture Of Epoxy System
Thesis Supervisor : Dr. Rajesh Kitey
Special Thanks :Dr. P.Venkitanarayan
By
SURVI RAGHU GOUD
13101049
M.Tech
A Thesis Defence in Partial Fulfilment of the Requirements for the Degree of Master of Technology
OUTLINE
• MOTIVATION
• OBJECTIVES
• MATHEMATICAL FORMULATION
• MATERIAL PREPARATION AND
CHARACTERIZATION
• EXPERIMENTAL METHODS
• RESULTS AND DISCUSSION
• CONCLUSION
MOTIVATION
3/31
Epoxy resin react with co-reactants (hardeners) and form thermosets
with desired properties.
MOTIVATION
• Tailoring the properties by controlling the factors affecting its properties –
– Composition of epoxy• Resin/hardener ratio
– Curing condition• Temperature
4/31
OBJECTIVES • To find the elastic properties of anhydride-cured Epoxy system
for the six Resin/Hardener (R/H) Ratios.
• To investigate the Dynamic Fracture behaviour of all the epoxy variants.
6/31
Multi parameter Representation of the Strain field
• The stresses expressed in the generalized form are
•
where
Ref: “strain gage methods for measuring the opening-mode stress intensity factor,
dzdYYdz
dZZwhere
YYyZyxy
YyZyZyy
YYyZyZxx
',',
Im'Re'Re'Im'ImRe
Re2'Im'ImRe
M
m
mZmBzY
N
n
nZnAzZ
0
)(
0
21
)(
• Plane stress-strain relations:
• Put n=0,1 and m=0,1 in the equation
YYyZyG
YYyZyZE
YYyZyZYyZyZYYyZyZ
EG
E
E
xy
yy
yyxxxx
xyxy
xxyyyy
yyxxxx
Im'Re'Re
Re2'Im)1('Im)1(Re)1(Similarly,
Re2'Im)1('Im)1(Re)1('Im'ImReRe2'Im'ImRe
1
)(1
)(1
21
123
0
21
121
0
21
21'
zAzAZ
zAzAZ
Ref: “strain gage methods for measuring
•
Ref: “strain gage methods for measuring
2sin
2cos
21
23sin
23cos
21
21
21'
2sin
2cos
2sin
2cos
21
123
0
221
12
323
0
21
121
0
221
122
1
0
irAirA
erAerAZ
and
irAirA
erAerAZ
ii
ii
YSimilarly,
)sin(cos10B irB
BdtdY
Y '
Four parameter strain field relative to a rotated coordinate system
• From the first invariant of strain,
• And the complex form of the strain transformation equation is
•
where Ref: “strain gage methods for measuring
yyxxyyxx ''''
ixyxxyyyxxxyy eii 2
'''''' )()(
2sinsin2cos)2cos(2sinsin212cos
2sin
2cos
)2cos(2sin2
3cossin212cos
23sinsin
21
2cos2
122
1
1
021
0''
krBkrA
kBkrAxx
Single gauge- Three parameter solution
• term can be eliminated if
Cos 2= k =)
• Next, set the coefficient of to zero, which gives = cot 2
• 𝟐𝛍𝝐𝒙 ′ 𝒙 ′=
𝑲 𝑰
√𝟐𝝅𝒓
−𝟏𝟐 [𝐤𝐜𝐨𝐬 𝜽𝟐−𝟏
𝟐 𝐬𝐢𝐧𝛉𝐬𝐢𝐧 𝟑𝜽𝟐 𝐜𝐨𝐬𝟐𝛂+𝟏𝟐 𝐬𝐢𝐧𝛉𝐜𝐨𝐬 𝟑𝜽𝟐 𝒔𝒊𝒏𝟐𝜶 ]
MATERIAL PREPARATIONMATERIALS-
• Epoxy Resin: DGEBA (Di-glycidyl ether of Bisphenol-A ), (LY556)
• Curing agent: MTHPA (Methyl Tetra hydrophthalic anhydride, (HY917)
• Accelerant: 2,4,5-tris[(dimethylamino)methyl]-Phenol (DMP-30)
• Cure period: 80 °C for 3 h, followed by 140 °C for 12 h
• R/H Ratios (by weight):- 100:40, 100:60, 100:80, 100:100,
100:120 and 100:140
7/31
MATERIAL PREPARATION- TENSILE & FRACTURE SPECIMENS• Tensile specimens : ASTM D638 : Type –I configuration
8/31
Material Preparation-Strain gauge mounting
9/31
MATERIAL PREPARATION- FRACTURE SPECIMENS
10/31
MATERIAL PREPARATION- FRACTURE SPECIMENS
EXPERIMENTAL METHODS- TENSILE TESTS CHARACTERIZATION OF ELASTIC PROPERTIES
Tensile Test setup for finding Young’s modulus:
• Displacement rate : 0.5 mm/min• Extensometer gauge length : 25 mm
COMPARISION OF STRESS-STRAIN BEHAVIOUR OF DIFFERENT R/H RATIOS
• Speed of Testing : 0.5
mm/min
• Overlapping initial region
COMPARISON OF YOUNG’S MODULUS
• Loading rate : 0.5 mm/min
Tensile Test setup for finding Poisson’s Ratio:
• Sampling rate : 100S/s• Half bridge-connection
COMPARISION OF LATERAL STRAIN –LONGITUDINAL STRAIN BEHAVIOUR FOR DIFFERENT R/H RATIOS
• Loading rate : 0.5 mm/min
COMPARISON OF POISSON’S RATIO
Calculation Of parameters for fracture samples :
EXPERIMENTAL METHODS- FRACTURE TESTS
12/31
EXPERIMENTAL METHODS- FRACTURE TESTS
EXPERIMENTAL METHODS- FRACTURE TESTS
13/31
• Pressure : 0.5 Kg/
• Sampling Frequency : 1M Hz
0 1000 2000 3000 4000 5000 6000
-0.003
-0.002
-0.001
0
0.001
0.002
0.003
Average Inc Strain SG
Time (μs)
inci
dent
, ref
lect
ed a
nd st
rain
pul
ses
Ist = 450 secRst = 2814 sec
t= d= 1540 mm= 1302.876 m/s
= 6.25 m/s
Representative Data of Strain-Time plots for different R/H ratios
0 20 40 60 80 100 120 1400
200
400
600
800
1000
1200
100:40100:60100:80100:100100:120100:140
Time (µ sec)
ε_rr
(μ s
train
)
Comparison of Fracture toughness of all the six R/H ratios
CONCLUSIONS• Elastic modulus changing slightly by R/H ratio in the tested epoxy
variants and was observed to be highest for stoichiometric ratio, 100:80
• Poisson’s ratio was observed to be least for stoichiometric ratio, 100:80.
• All R/H ratios showed the monotonically increasing strain history
variation until the crack initiation.
• The Fracture Toughness was observed to be least for the 100:40 R/H
ratio and 0.578 MPa for 100:80 R/H ratio.
28/31
SCOPE FOR FURTHER WORK
• Dynamic Fracture properties of bimaterials prepared with epoxy variants
could be studied and the Finite Element Simulations on them could be
investigated to understand the failure criterion in these materials.
• The impact test could be done for deeply cracked specimens of the
different R/H ratios.
30/31
THANK YOU!