comparison of strength behavior of unidirectional hmc and hsc composite subjected to biaxial loading...
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Comparison of strength behavior of unidirectional HMC and HSC composite
subjected to biaxial loading
J. Krystek, R. Kottner, L. Bek
19th Conference on Materials and Technology; 22 and 23 November 2011, Portorož, Slovenia
Outline
• Introduction• Material model• Mechanical properties• Failure criteria• Experiments• Numerical analysis• Summary
Introduction
– Currently, the failure of composite is well predictable only in basic cases
– Biaxial tests shown dependence of specimen strength on the ratio of tension and compression
Wrapped pin joint
Mechanical propertiesTensile test
Type of
fibers[GPa] [GPa] [ - ] [GPa] [GPa] [ - ] [MPa] [MPa] [MPa] [MPa] [MPa] [ ° ]
HSC 120.0 8.0 0.337 4.8 110.0 1.11 1800 850 55 213 82 59
HMC 200.0 6.8 0.290 6.5 128.0 1.28 1770 685 42 160 60 57
1E 2E 12 012G
012 12 n T X CX T Y C Y L S
Elasticity and strength parameters of composite
0 α
Compression test – type I Compression test – type II( E1, E2 , ν12 , XT, YT ) ( YC, α0 ) ( XC, Y C, α0 )
ASTM D 3410ASTM D 3039
Material modelo Unidirectional composite material
66
66
2322
222312
232212
121211
00000
00000
002000
000
000
000
C
C
CC
CCC
CCC
CCC
C
Stiffness matrix of transverse isotropic material
– 5 independence components of stiffness matrix (C11 , C12 , C22 , C23 , C66)– 5 independence material constants (E1, E2 , G12 , υ12 , υ13)
1212
11
012
12012
012
1212
1nn
τ
γG
GγG
– Nonlinear function with constant asymptote was used for shear modulus G12 :
– This material model is not standard part of used FEM system MSC.Marc, therefore it was implemented into MSC.Marc system.
Force and extension dependencies
Failure criteria
o FIBRE FAILURE
1T1 X
FI
12L
213
212
2
T1
SXFI
1T1 X
FI
1f
T1
PX
FI
01
o MATRIX FAILURE
– Maximum stress
– Hashin
– LaRC04 #3
– adjusted LaRC04 #3
– Maximum stress
– Hashin
– LaRC04 #2
– adjusted LaRC04 #2
01
01
01
1C3 Y
FI 03
12
12 2L
213
212
2T
32223
2
T32
C32
2
T
C
SSSYS
YFI
032
12
nLL
L2
nTT
T
SS
FI
0 ;0 13 12
1nLL
L2
1nTT
T
MM PSPS
FI
0 ;0 13
Schema of biaxial test
Testing machine
– Biaxial test
– Standard testing machine Zwick/Roell Z050 was supplemented by second loading axis for the localized compression
– The second loading axis consisted of power machine vice VMC-130 and HBM C9B compact force transducer
Experiments
– Loading was applied in two basic steps
Loading steps
– Specimens were cut using water jet from unidirectional composite plates, which were made from 8 layers of prepreg
– Geometry parameters of specimens
HSC composite
b = 5.0 mm, h = 2.2 mm, l = 240 mm
HMC composite
b = 4.8 mm, h = 2.0 mm, l = 240 mm
– Geometry parameters of compression element:
w = 20 mm, v = 10 mm, R = 1 mm
– Specimens were supplemented with aluminium pads on both sides.
– All pads were bonded on the specimens by Araldit AV 138M + HV 998 adhesive
Geometry parameters
Specimens with aluminium pads
Specimens
Experiments - results
Dependences of specimen strength on the combination of tensile and compression forces
HSC HMC
Failure of matrix in biaxial test Failure of fibres in biaxial test
– Compressive strength (matrix failure) is increasing with the tensile force
– Tensile strength (fibre failure) is decreasing with the compressive loading
b = 5.0 mm, h = 2.2 mm b = 4.8 mm, h = 2.0 mm
Numerical analysis
o FEM system: MSC.Marc
Boundary condition
– Regarding symmetry of the specimen, only one quarter of the specimen was modelled
– Loading was applied in two basic steps which correspond with experiment
– Compressive loading was applied by force acting on contact surface which represented compressive element
– Friction was neglected
Modeled quarter
Numerical analysis
Failure index for Hashin - fibre failure
Failure index for LaRC04 #2 - matrix failure Failure index for Maximum stress - matrix failure
o HSC composite
Summary
– Selected stiffness and strength parameters of composites were identified
– Composites had high modulus carbon (HMC) fibres and high strength carbon (HSC) fibres
– Strength analysis of the composites subjected to biaxial loading was performed
– Experimental specimens were loaded in two perpendicular directions
– Specimens were exposed to the combination of the tension in the fibre direction and the localized compression in the transverse direction
– Loading was applied in two basic steps
– Experiments showed similar dependence of specimen strength of both types of composite on the ratio of tension and compression
– Compressive strength is increasing with the tensile force
– Tensile strength is decreasing with the compressive force
– Predictive capabilities of different failure criteria for composite materials were tested in the failure analysis - Maximum stress, Hashin, LaRC04
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