advances and challenges in large scale ... - spe automotive · 23 presentation name conclusions •...
TRANSCRIPT
Advances and
Challenges in Large
Scale Polymer
Additive
Manufacturing
Vlastimil Kunc Ph.D.
Oak Ridge National Laboratory
2 Presentation name
Extrusion Deposition
Polymer Additive Manufacturing
Large Scale - 3D printed Shelby Cobra
(NPE booth 14041 – Techmer)
Small Scale - 3D printed gear
“Fused Deposition Modeling”
“Fused Filament Fabrication”
“Extrusion Deposition”
3 Presentation name
Printed Carbon Fiber Composites – Small
Beginnings, Small Scale
CF-ABS
2x strength
4x stiffness
ABS
CF-ABS
• Compounded filament printed on Solidoodle 3 (modified)
• 10-40% CF by weight
Dramatically reduced distortion
Lindahl ACCE Poster (2013)
4 Presentation name
Extrusion Deposition of Composites on
Large Scale
• Pellet-to-Part: Enables manufacturing of
large components using pelletized feed.
• High Deposition rates: currently 10-100
lb/hr
• Highly anisotropic properties of deposited
composites
• Residual stresses and process dependent
layer adhesion
5 Presentation name
BAAM: Big Area Additive Manufacturing
• Cement
• Plastics
• Carbon Reinforced Plastics
• Build Volume > 500 ft3
IR camera mounted on
extrusion arm
• FLIR A35
• Radiometric
• Longwave camera
• 30 or 60 fps
6 Presentation name
BAAM onboard IR imaging
FLIR A35
~7 oz.
Measure…
• Actual extrusion temperatures
• Temperature decay rates
• Temperature of substrate layer
• Temperature profile of part
7 Presentation name
Thermal Imaging of BAAM
8 Presentation name
Thermal Imaging of BAAM
9 Presentation name
Printing with amorphous and semi-
crystalline materials
10 Presentation name
BAAM Dog Bones
0° - 0° 90° - 90° 45° - 135°
1) Print out plates of various orientations (20 x 20 x 1 inch)
3) Dry at 50°C for at least 48 hours (ASTM D618-B) 5) Tensile test within 30 minutes (ASTM D638)
2) Mill plates flat (0.75”)
& water jet dog bones
4) Desiccant chamber at 23°C for at least 15 hours (ASTM D618-B)
11 Presentation name
BAAM Dog Bones
13% CF-ABS Spec = 7.72 GPa
ABS Spec = 2.25 GPa
0-0 90-90 45-135 0-0 90-90 45-135
ABS 13% CF-ABS
12 Presentation name
BAAM Dog Bones 13% CF-ABS Spec = 78.6 MPa
ABS Spec = 40.2 MPa
0-0 90-90 45-135 0-0 90-90 45-135
ABS 13% CF-ABS
13 Presentation name
CF-ABS BAAM Dog Bones 0° - 0° 90° - 90° 45°- 135°
Fracture surfaces of carbon
fiber reinforced ABS
samples
• Splitting along interface is
apparent
• Sudden brittle failure
Significant pattern
dependent variability in
strength and stiffness
14 Presentation name
Pellet vs Bead Porosity N
ea
t A
BS
1
3%
CF
-AB
S
Pellet Fracture (200x) BAAM Fracture (50x) BAAM Fracture (200x)
15 Presentation name
Extruder Re-design
Original Design
20% CF – ABS
15.9 lb/hr
20% CF – ABS
15.3 lb/hr
New Design
20% CF – ABS
45.2 lb/hr
20% CF – ABS
39.2 lb/hr
Going to 80 lbs/h!!
16 Presentation name
Modeling - Motivation
Big Area Additive Manufacturing
Large Scale: 12’ x 6’ x 3’
Reduced Cost: $1-5/lb
High Deposition Rate: >40 lbs/h
Challenge:
• Large parts distort and crack
• Need to understand impact of part geometry and processing conditions
• Predict thermal and stress gradients
• Identify potential areas for crack initiation
17 Presentation name
BAAM Process Modeling
1D Thermo-Mechanical Model
New layer added every Δtlayer at deposition temperature, Tdep
Ambient temperature, T∞
Convection coefficient, h
Layer 1
Layer 2
Layer 3
Layer n
⁞
⁞
⁞
⁞
Layer n-1
Build plate temperature, Tbed
w
Assumptions:
Temperature independent properties
Isothermal bed
Instantaneous deposition of entire layer
Uniform thorough-thickness temperature
Convection
T∞
Radiation
Model Definition
Ti - 1
Ti
Ti + 1
Heat Transfer Mechanisms
Tbed Conduction
DRAFT
18 Presentation name
BAAM 1D Process Model
Experimental Validation
experiment
model
layer 22 layer 44 layer 66 layer 88
10 min.
20 min.
30 min.
0
0.36
Tss
data line
19 Presentation name
3D Finite Element Model
Big Area Additive Manufacturing
3D Model BAAM Print Parameters
Tool Path Generation
Automated Finite Element Mesh
Process & Damage Analysis
20 Presentation name
Automated Model Generation
•From Gcode to Multi-scale progressive failure with GENOA GUI
20
Mesh generated printer code (Gcode)
Include material and orientations from printer code
Mesh generator capabilities includes:
• Finite element solid mesh generation from gcode
• Automatic material orientation from gcode
• Material and structural property assignment
• Load and boundary condition assignment
• Multi-Scale Failure Mechanisms
Attributes of mesh generator
Bald spots visualization
Residual stress
Deformation
21 Presentation name
Solution approach
•Integrated approach: model generator; characterize chopped fiber; progressive damage/fracture analysis
21
Multiple solution strategies have been considered
Tensor orientation
22 Presentation name
Highlights
•Potential delaminated areas can be identified
22
Global visualization of the delaminations
Local visualization of the delaminations (overexaturated displacements for the sake of visualization (x3))
Delaminations
Delaminations
Delaminations in the mid-console
Driving direction
Delaminations
Delaminations
Delaminations
23 Presentation name
Conclusions
• Pellet-to-Part additive process was developed that enables manufacturing of large
components using low cost pelletized feed.
• High deposition rates (10-100 lb/hr) allow rapid production of components and control
of temperature profiles.
• Low CTE second phase reinforcements in polymer matrix improve mechanical
properties and dimensional stability of printed parts
• Models were developed to simulate deposition process
• Remaining challenges
• Porosity in printed material
• Z-dimension strength
• Validation of models and software tools
