understanding the role of material properties in simulations- part … · 2015. 5. 26. ·...
TRANSCRIPT
Datapoint Testing Services 1
Understanding the Role of
Material Properties in
Simulations- Part 2
Hubert Lobo
Datapoint Testing Services 2
Introduction -
Virtual Manufacturing (CAE)
The computer as a virtual process
laboratory
– understand the process
– create and test scenarios
– make improvements at design stage
Datapoint Testing Services 3
Introduction- Material Properties
Plastics in simulation
– Each plastic has a unique property profile
– The importance of proper representation
=
Datapoint Testing Services 4
Scheme of presentation
Define property requirements
Identify evaluation parameters
Follow the injection molding process
Identify the role of material properties at
each stage of the process
Datapoint Testing Services 5
Modes of analysis- mold filling
mold filling
mold cooling
post filling simulations
shrink/warp
Datapoint Testing Services 6
Data requirements- mold filling
viscosity v/s shear rate, temperature
thermal conductivity v/s temperature
specific heat v/s temperature
melt density
no flow temperature M
eject temperature M
transition temperature C
Datapoint Testing Services 7
Viscosity
P
Datapoint Testing Services 8
Thermal Conductivity
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0 50 100 150 200
Temperature °C
Th
erm
al C
ond
uct
ivit
y W
/m·K
Datapoint Testing Services 9
Specific Heat
0
1000
2000
3000
4000
5000
6000
0 100 200 300 400
Temperature °C
Spe
cific
Hea
t J/
kg·°
C
Datapoint Testing Services 10
Melt Density
High-pressure flow rate measurements
Instrument-capillary rheometer
P
Datapoint Testing Services 11
No Flow Temperature
Moldflow requirement:
Temperature at which flow
ceases under a particular applied
load. (133 Bar)
Instrument-capillary rheometer P
V
Datapoint Testing Services 12
DSC Transitions
0
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0
5 0 0 0
6 0 0 0
0 1 0 0 2 0 0 3 0 0 4 0 0
Te m p e r a t u r e °C
Sp
ecif
ic H
ea
t J
/kg
·°C
Eject Temperature
Transition Temperature
Datapoint Testing Services 13
Additional Data - post filling
pvT
Datapoint Testing Services 14
pvT
A: High pressure dilatometry
B: Piston-cylinder method
– Temperature ranges
» Process to ambient
– Pressure Range
» 0-200 MPa
Datapoint Testing Services 15
Additional Data - Moldflow
shrink/warp
Shrinkage/Warpage coefficients
Datapoint Testing Services 16
Shrinkage coefficients
Injection molding of grid-marked tags
Different thicknesses
Several process conditions
Bidirectional measurement of shrinkage
Correlate using Moldflow
Datapoint Testing Services 17
Evaluation Parameters
material property based parameters
evaluate effects seen in the process
understand and interpret simulation results
compare materials
develop criteria for selection based on
desired processability
Datapoint Testing Services 18
Properties of Evaluation
Parameters
Easily calculated
Estimates of actual parameters
Must be considered along with other
relevant parameters
Datapoint Testing Services 19
Viscosity V
isco
sity
Pa
·s
10.0
100.0
1000.0
10000.0
10 100 1000 10000
Shear Rate 1/s
300 °C
320 °C
340 °C
Datapoint Testing Services 20
Evaluation Parameters-Viscosity
Nature of the 2nd order matrix
– Temperatures
» Tmelt
» Tmelt+20
» Tmelt-20
– Shear rates
» 100
» 1000
» 10000
T
Tmelt-20 1000
Tmelt 100
Tmelt 1000
Tmelt 10000
Tmelt+20 100 Tmelt+20 1000
Datapoint Testing Services 21
Evaluation Parameters -Viscosity
Temperature sensitivity of viscosity
– TVL= ( ln- ln ) / 20
– TVH = ( ln- ln ) / 20
T
Tmelt-20 1000
Tmelt 100
Tmelt 1000
Tmelt 10000
Tmelt+20 100 Tmelt+20 1000
Datapoint Testing Services 22
Evaluation Parameters -Viscosity
Rules
– if TV is large, material is highly sensitive
– TVL > TVH
– Semi-crystalline
» TVL == TVH
– Amorphous
» TVL >> TVH PP
ABS
PS
PC
PPA
0 10 20 30 40 50 60
TV* 1E+03
PP
ABS
PS
PC
PPA
Resin
Datapoint Testing Services 23
Evaluation Parameters -Viscosity
Shear sensitivity of viscosity
– Defining a limited power-law index.
» SHB= ( ln- ln ) / 2.303 T
Tmelt-20 1000
Tmelt 100
Tmelt 1000
Tmelt 10000
Tmelt+20 100 Tmelt+20 1000
Datapoint Testing Services 24
Evaluation Parameters -Viscosity
Rules
– 0<SHB < 1
– Large SHB = shear sensitive
– Important exception:
» broad newtonian
(eg. PC)
Vis
cosi
ty P
a·s
10.0
100.0
1000.0
10000.0
10 100 1000 10000
Shear Rate 1/s
300 °C
320 °C
340 °C
Datapoint Testing Services 25
Thermal mass
– TMASS=(rho*Cp)
– units = J/m3.K
– True measure of heat capacity
Rules
– Large TMASS = cools slowly
– Large TMASS = more heat to remove
Evaluation Parameters- Thermal
Steel
TMASS=3.6e6
Cp=460
Plastic
TMASS=1.9e6
Cp=1700
Datapoint Testing Services 26
Evaluation Parameters- Thermal
Thermal diffusivity
– a = (k / TMASS)
– units = m2/s
– Measure of heat transfer rate
Rules
– Large a = cools quickly
PP/Talc
a = 8.7e-8
k = 0.21
PP
a = 7.7e-8
k = 0.17
Datapoint Testing Services 27
Evaluation Parameters- Thermal
No-flow temperature
– NOFLO
– maps closely with crystallization temp
– 20-30C higher than Tg (amorphous materials)
Datapoint Testing Services 28
Evaluation Parameters- Thermal
Eject Temperature
– EJECT
Rules
– High (EJECT - TMOLD) = lower cycle time
Datapoint Testing Services 29
Evaluation Parameters- PVT
0.80
0.85
0.90
0.95
1.00
1.05
1.10
0 50 100 150 200 250
Temperature °C
Sp
ecif
ic V
olu
me
m /
kg
x 1
00
0
Datapoint Testing Services 30
Evaluation Parameters-PVT
Nature of the PVT matrix
– Temperatures
» TS1 - TS7
» TB1-TB2
» TM1-TM4
– Pressures
» 0 MPa
» 160 MPa
T P V
TS1 0 VS1
TS2 0 VS2
TS3 0 VS3
TS4 0 VS4
TS5 160 VS5
TS6 160 VS6
TS7 160 VS7
TB1 0 VB1
TB2 160 VB2
TM1 0 VM1
TM2 0 VM2
TM3 160 VM3
TM4 160 VM4
Datapoint Testing Services 31
Evaluation Parameters- PVT
Volumetric expansion coefficient (VEC)
– VEC=dV/dT
– VECS=(VS1-VS2) / (TS1-TS2)
– VECM=(VM1-VM2) / (TM1-TM2)
T P V
TS1 0 VS1
TS2 0 VS2
TS3 0 VS3
TS4 0 VS4
TS5 160 VS5
TS6 160 VS6
TS7 160 VS7
TB1 0 VB1
TB2 160 VB2
TM1 0 VM1
TM2 0 VM2
TM3 160 VM3
TM4 160 VM4
0 MPa
Datapoint Testing Services 32
Evaluation Parameters- PVT
Compressibility (COM)
– COM = dV/dP
– COMS = (VS1-VS5) / 160
– COMM = (VM1-VM3) / 160
0
160
T P V
TS1 0 VS1
TS2 0 VS2
TS3 0 VS3
TS4 0 VS4
TS5 160 VS5
TS6 160 VS6
TS7 160 VS7
TB1 0 VB1
TB2 160 VB2
TM1 0 VM1
TM2 0 VM2
TM3 160 VM3
TM4 160 VM4
Datapoint Testing Services 33
In the runner..
very hot resin (TVH)
high shear rate (SHB)
viscous heating (TMASS, TVH)
flow around corners (e) dPc
Datapoint Testing Services 34
At the gate
extensional flow (e)
very high shear rates (SHB)
viscous heating (TMASS, TVH)
dPg
Datapoint Testing Services 35
Within the part
Frozen layer formation
– a
– NOFLO
– CRY
Datapoint Testing Services 36
Within the part
Flow around corners
– additional pressure loss (e)
Datapoint Testing Services 37
Within the part
Thick and thin sections
– additional pressure loss (e)
Datapoint Testing Services 38
Weld lines...
melt front temperature
– a
available pressure
Datapoint Testing Services 39
End of fill
2E+1
1E+3
250 260
275
290
1.E+1
1.E+2
1.E+3
1.E+4
Vis
co
sit
y
low shear rates (TVL)
low temperature
Datapoint Testing Services 40
Packing it in..
0
249
219
189
159
129
99
69
40
50 100
150 200
1.0000
Vo
lum
e
Semi-crystalline polymer
– Factors:
» COMM
» TVL
Datapoint Testing Services 41
Cooling off
cooling polymer
– a
– CRY, VEC
freeze off
– NOFLO
– TVL-TVH
249
219
189
159
129
99
69
40
50 100
150 200
1.0000
Vo
lum
e
Datapoint Testing Services 42
Conclusion
Evaluation parameters are:
– tools to examine simulation results
– aid in understanding resin behavior in the mold
– aid in selection of resin based on desired
processability
– easy to calculate and use every day
Questions, call us; 1-888-DATA-4-CAE
Datapoint Testing Services 43
Future considerations
extensional flow situations
accumulation of residual stresses
stress relaxation
warpage
Datapoint Testing Services 44
Datapoint Testing Services 45
Effect of viscosity
shear thinning behavior reduces pressure
penalty +
high temperature sensitivity of viscosity -
high pressure raises viscosity -
high shear rate induces viscous heating +
Datapoint Testing Services 46
Effect of thermal conductivity
high solid conductivity reduces cycle time +
high conductivity tightens process window -
Datapoint Testing Services 47
Effect of PVT
shows how plastic will solidify
shows shrinkage level