This paper studies how to control boundary slope of optimized parts in density-based topology optimization for additive manufacturing (AM). Boundary slope of a part affects the amount of support structure required during its fabrication by additive processes. Boundary slope also has a direct relation with the resulting surface roughness from the AM processes, which in turn affects the heat transfer efficiency. By constraining the minimal boundary slope, support structures can be eliminated or reduced for AM, and thus, material and postprocessing costs are reduced; by constraining the maximal boundary slope, high-surface roughness can be attained, and thus, the heat transfer efficiency is increased. In this paper, the boundary slope is controlled through a constraint between the density gradient and the given build direction. This allows us to explicitly control the boundary slope through density gradient in the density-based topology optimization approach. We control the boundary slope through two single global constraints. An adaptive scheme is also proposed to select the thresholds of these two boundary slope constraints. Numerical examples of linear elastic problem, heat conduction problem, and thermoelastic problems demonstrate the effectiveness and efficiency of the proposed formulation in controlling boundary slopes for additive manufacturing. Experimental results from metal 3D printed parts confirm that our boundary slope-based formulation is effective for controlling part self-support during printing and for affecting surface roughness of the printed parts.

References

1.
Bendsøe
,
M. P.
, and
Kikuchi
,
N.
,
1988
, “
Generating Optimal Topologies in Structural Design Using a Homogenization Method
,”
Comput. Methods Appl. Mech. Eng.
,
71
(
2
), pp.
197
224
.
2.
Bendsøe
,
M. P.
,
1989
, “
Optimal Shape Design As a Material Distribution Problem
,”
Struct. Optim.
,
1
(
4
), pp.
192
202
.
3.
Zhou
,
M.
, and
Rozvany
,
G.
,
1991
, “
The COC Algorithm, Part II: Topological, Geometrical and Generalized Shape Optimization
,”
Comput. Methods Appl. Mech. Eng.
,
89
(
1–3
), pp.
309
336
.
4.
Xie
,
Y.
, and
Steven
,
G. P.
,
1993
, “
A Simple Evolutionary Procedure for Structural Optimization
,”
Comput. Struct.
,
49
(
5
), pp.
885
896
.
5.
Wang
,
M. Y.
,
Wang
,
X.
, and
Guo
,
D.
,
2003
, “
A Level Set Method for Structural Topology Optimization
,”
Comput. Methods Appl. Mech. Eng.
,
192
(
1
), pp.
227
246
.
6.
Allaire
,
G.
,
Jouve
,
F.
, and
Toader
,
A.
,
2004
, “
Structural Optimization Using Sensitivity Analysis and a Level-set Method
,”
J. Comput. Phys.
,
194
, pp.
363
393
.
7.
Sokołowski
,
J.
, and
Żochowski
,
A.
,
2001
, “Topological Derivative in Shape Optimization,”
Encyclopedia of Optimization
,
Springer
,
New York
, pp.
2625
2626
.
8.
Suresh
,
K.
,
2013
, “
Efficient Generation of Large-Scale Pareto-Optimal Topologies
,”
Struct. Multidiscip. Optim.
,
47
(
1
), pp.
49
61
.
9.
Lopes
,
C. G.
,
Santos
,
R. B. d.
, and
Novotny
,
A. A.
,
2015
, “
Topological Derivative-Based Topology Optimization of Structures Subject to Multiple Load-Cases
,”
Latin Am. J. Solids Struct.
,
12
(
5
), pp.
834
860
.
10.
Deaton
,
J. D.
, and
Grandhi
,
R. V.
,
2014
, “
A Survey of Structural and Multidisciplinary Continuum Topology Optimization: Post 2000
,”
Struct. Multidiscip. Optim.
,
49
(
1
), pp.
1
38
.
11.
Gibson
,
I.
,
Rosen
,
D.
, and
Stucker
,
B.
,
2014
,
Additive Manufacturing Technologies: 3D Printing, Rapid Prototyping, and Direct Digital Manufacturing
,
Springer
,
New York
.
12.
Lefky
,
C. S.
,
Zucker
,
B.
,
Wright
,
D.
,
Nassar
,
A. R.
,
Simpson
,
T. W.
, and
Hildreth
,
O. J.
,
2017
, “
Dissolvable Supports in Powder Bed Fusion-Printed Stainless Steel
,”
3D Printing Additive Manuf.
,
4
(
1
), pp.
3
11
.
13.
Strano
,
G.
,
Hao
,
L.
,
Everson
,
R. M.
, and
Evans
,
K. E.
,
2013
, “
Surface Roughness Analysis, Modelling and Prediction in Selective Laser Melting
,”
J. Mater. Process. Technol.
,
213
(
4
), pp.
589
597
.
14.
Ventola
,
L.
,
Robotti
,
F.
,
Dialameh
,
M.
,
Calignano
,
F.
,
Manfredi
,
D.
,
Chiavazzo
,
E.
, and
Asinari
,
P.
,
2014
, “
Rough Surfaces With Enhanced Heat Transfer for Electronics Cooling by Direct Metal Laser Sintering
,”
Int. J. Heat Mass Transfer
,
75
, pp.
58
74
.
15.
Snyder
,
J. C.
,
Stimpson
,
C. K.
,
Thole
,
K. A.
, and
Mongillo
,
D. J.
,
2015
, “
Build Direction Effects on Microchannel Tolerance and Surface Roughness
,”
ASME J. Mech. Des.
,
137
(
11
), p.
111411
.
16.
Bikas
,
H.
,
Stavropoulos
,
P.
, and
Chryssolouris
,
G.
,
2016
, “
Additive Manufacturing Methods and Modelling Approaches: A Critical Review
,”
Int. J. Adv. Manuf. Technol.
,
83
(
1–4
), pp.
389
405
.
17.
Stimpson
,
C. K.
,
Snyder
,
J. C.
,
Thole
,
K. A.
, and
Mongillo
,
D.
,
2016
, “
Roughness Effects on Flow and Heat Transfer for Additively Manufactured Channels
,”
ASME J. Turbomach.
,
138
(
5
), p.
051008
.
18.
Kirsch
,
K. L.
, and
Thole
,
K. A.
,
2017
, “
Pressure Loss and Heat Transfer Performance for Additively and Conventionally Manufactured Pin Fin Arrays
,”
Int. J. Heat Mass Transfer.,
108
(
Pt. B
), pp.
2502
2513
.
19.
Delgado
,
J.
,
Ciurana
,
J.
, and
Rodríguez
,
C. A.
,
2012
, “
Influence of Process Parameters on Part Quality and Mechanical Properties for DMLS and SLM With Iron-Based Materials
,”
Int. J. Adv. Manuf. Technol.
,
60
(
5–8
), pp.
601
610
.
20.
Liu
,
J.
, and
Ma
,
Y.
,
2016
, “
A Survey of Manufacturing Oriented Topology Optimization Methods
,”
Adv. Eng. Softw.,
100
, pp.
161
175
.
21.
Zhou
,
M.
,
Fleury
,
R.
,
Shyy
,
Y.-K.
,
Thomas
,
H.
, and
Brennan
,
J.
,
2002
, “
Progress in Topology Optimization With Manufacturing Constraints
,”
9th AIAA/ISSMO Symposium on Multidisciplinary Analysis and Optimization
,
Atlanta, GA
,
Sept. 4–6
, p.
5614
.
22.
Xia
,
Q.
,
Shi
,
T.
,
Wang
,
M. Y.
, and
Liu
,
S.
,
2010
, “
A Level Set Based Method for the Optimization of Cast Part
,”
Struct. Multidiscip. Optim.
,
41
(
5
), pp.
735
747
.
23.
Xia
,
Q.
,
Shi
,
T.
,
Wang
,
M. Y.
, and
Liu
,
S.
,
2011
, “
Simultaneous Optimization of Cast Part and Parting Direction Using Level Set Method
,”
Struct. Multidiscip. Optim.
,
44
(
6
), pp.
751
759
.
24.
Gersborg
,
A. R.
, and
Andreasen
,
C. S.
,
2011
, “
An Explicit Parameterization for Casting Constraints in Gradient Driven Topology Optimization
,”
Struct. Multidiscip. Optim.
,
44
(
6
), pp.
875
881
.
25.
Sato
,
Y.
,
Yamada
,
T.
,
Izui
,
K.
, and
Nishiwaki
,
S.
,
2017
, “
Manufacturability Evaluation for Molded Parts Using Fictitious Physical Models, and Its Application in Topology Optimization
,”
Int. J. Adv. Manuf. Technol.
,
92
(
1–4
), pp.
1391
1409
.
26.
Li
,
Q.
,
Chen
,
W.
,
Liu
,
S.
, and
Fan
,
H.
,
2018
, “
Topology Optimization Design of Cast Parts Based on Virtual Temperature Method
,”
Comput.-Aided Des.
,
94
, pp.
28
40
.
27.
Guest
,
J. K.
, and
Zhu
,
M.
,
2012
, “
Casting and Milling Restrictions in Topology Optimization Via Projection-Based Algorithms
,”
ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference
,
Chicago, IL
,
Aug. 12–18
, American Society of Mechanical Engineers, New York, pp. 913–920.
28.
Li
,
H.
,
Li
,
P.
,
Gao
,
L.
,
Zhang
,
L.
, and
Wu
,
T.
,
2015
, “
A Level Set Method for Topological Shape Optimization of 3D Structures With Extrusion Constraints
,”
Comput. Methods Appl. Mech. Eng.
,
283
, pp.
615
635
.
29.
Zhou
,
Y.
, and
Saitou
,
K.
,
2018
, “
Gradient-Based Multi-Component Topology Optimization for Stamped Sheet Metal Assemblies (MTO-S)
,”
Struct. Multidiscip. Optim.
,
58
(
1
), pp.
83
94
.
30.
Zhang
,
S.
,
Norato
,
J. A.
,
Gain
,
A. L.
, and
Lyu
,
N.
,
2016
, “
A Geometry Projection Method for the Topology Optimization of Plate Structures
,”
Struct. Multidiscip. Optim.
,
54
(
5
), pp.
1173
1190
.
31.
Zhang
,
S.
,
Gain
,
A. L.
, and
Norato
,
J. A.
,
2018
, “
A Geometry Projection Method for the Topology Optimization of Curved Plate Structures With Placement Bounds
,”
Int. J. Numer. Methods Eng.
,
114
(
2
), pp.
128
146
.
32.
Poulsen
,
T. A.
,
2003
, “
A New Scheme for Imposing a Minimum Length Scale in Topology Optimization
,”
Int. J. Numer. Methods Eng.
,
57
(
6
), pp.
741
760
.
33.
Guest
,
J.
,
Prévost
,
J.
, and
Belytschko
,
T.
,
2004
, “
Achieving Minimum Length Scale in Topology Optimization Using Nodal Design Variables and Projection Functions
,”
Int. J. Numer. Methods Eng.
,
61
(
2
), pp.
238
254
.
34.
Wang
,
F.
,
Lazarov
,
B.
, and
Sigmund
,
O.
,
2011
, “
On Projection Methods, Convergence and Robust Formulations in Topology Optimization
,”
Struct. Multidiscip. Optim.,
43
(
6
), pp.
767
784
.
35.
Qian
,
X.
, and
Sigmund
,
O.
,
2012
, “
Topological Design of Electromechanical Actuators With Robustness Toward Over-and Under-Etching
,”
Comput. Methods Appl. Mech. Eng.
,
253
, pp.
237
251
.
36.
Zhou
,
M.
,
Lazarov
,
B. S.
,
Wang
,
F.
, and
Sigmund
,
O.
,
2015
, “
Minimum Length Scale in Topology Optimization by Geometric Constraints
,”
Comput. Methods Appl. Mech. Eng.
,
293
, pp.
266
282
.
37.
Allaire
,
G.
,
Jouve
,
F.
, and
Michailidis
,
G.
,
2016
, “
Thickness Control in Structural Optimization Via a Level Set Method
,”
Struct. Multidiscip. Optim.
,
53
(
6
), pp.
1349
1382
.
38.
Guest
,
J. K.
,
2009
, “
Imposing Maximum Length Scale in Topology Optimization
,”
Struct. Multidiscip. Optim.
,
37
(
5
), pp.
463
473
.
39.
Wang
,
Y.
,
Zhang
,
L.
, and
Wang
,
M. Y.
,
2016
, “
Length Scale Control for Structural Optimization by Level Sets
,”
Comput. Methods Appl. Mech. Eng.
,
305
, pp.
891
909
.
40.
Thompson
,
M. K.
,
Moroni
,
G.
,
Vaneker
,
T.
,
Fadel
,
G.
,
Campbell
,
R. I.
,
Gibson
,
I.
,
Bernard
,
A.
,
Schulz
,
J.
,
Graf
,
P.
,
Ahuja
,
B.
, and
Martina
,
F.
,
2016
, “
Design for Additive Manufacturing: Trends, Opportunities, Considerations, and Constraints
,”
CIRP Annals-Manuf. Technol.
,
65
(
2
), pp.
737
760
.
41.
Brackett
,
D.
,
Ashcroft
,
I.
, and
Hague
,
R.
,
2011
, “
Topology Optimization for Additive Manufacturing
,”
Proceedings of the Solid Freeform Fabrication Symposium
,
Austin, TX
,
Aug. 8–10
, pp. 348–362.
42.
Leary
,
M.
,
Merli
,
L.
,
Torti
,
F.
,
Mazur
,
M.
, and
Brandt
,
M.
,
2014
, “
Optimal Topology for Additive Manufacture: a Method for Enabling Additive Manufacture of Support-Free Optimal Structures
,”
Mater. Des.
,
63
, pp.
678
690
.
43.
Gaynor
,
A. T.
,
Meisel
,
N. A.
,
Williams
,
C. B.
, and
Guest
,
J. K.
,
2014
, “
Topology Optimization for Additive Manufacturing: Considering Maximum Overhang Constraint
,”
15th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference
,
Atlanta, GA
,
June 16–20
, p.
2036
.
44.
Langelaar
,
M.
,
2016
, “
An Additive Manufacturing Filter for Topology Optimization of Print-Ready Designs
,”
Struct. Multidiscip. Optim.,
55
(
3
), pp.
871
883
.
45.
Langelaar
,
M.
,
2016
, “
Topology Optimization of 3D Self-Supporting Structures for Additive Manufacturing
,”
Additive Manuf.,
12
(
Pt. A
), pp.
60
70
.
46.
Qian
,
X.
,
2017
, “
Undercut and Overhang Angle Control in Topology Optimization: A Density Gradient Based Integral Approach
,”
Int. J. Numer. Methods Eng.
,
111
(
3
), pp.
247
272
.
47.
Mezzadri
,
F.
,
Bouriakov
,
V.
, and
Qian
,
X.
,
2018
, “
Topology Optimization of Self-supporting Support Structures for Additive Manufacturing
,”
Additive Manuf.
,
21
, pp.
666
682
.
48.
Asadpoure
,
A.
,
Guest
,
J. K.
, and
Valdevit
,
L.
,
2014
, “
Incorporating Fabrication Cost Into Topology Optimization of Discrete Structures and Lattices
,”
Struct. Multidiscip. Optim.
,
51
(
2
), pp.
385
396
.
49.
Mirzendehdel
,
A. M.
, and
Suresh
,
K.
,
2016
, “
Support Structure Constrained Topology Optimization for Additive Manufacturing
,”
Comput.-Aided Des.
,
81
, pp.
1
13
.
50.
Haber
,
R. B.
,
Jog
,
C. S.
, and
Bendsøe
,
M. P.
,
1996
, “
A New Approach to Variable-topology Shape Design Using a Constraint on Perimeter
,”
Struct. Optim.
,
11
(
1–2
), pp.
1
12
.
51.
Petersson
,
J.
, and
Sigmund
,
O.
,
1998
, “
Slope Constrained Topology Optimization
,”
Int. J. Numer. Methods Eng.
,
41
(
8
), pp.
1417
1434
.
52.
Clausen
,
A.
,
Aage
,
N.
, and
Sigmund
,
O.
,
2015
, “
Topology Optimization of Coated Structures and Material Interface Problems
,”
Comput. Methods Appl. Mech. Eng.
,
290
, pp.
524
541
.
53.
Clausen
,
A.
,
Aage
,
N.
, and
Sigmund
,
O.
,
2016
, “
Exploiting Additive Manufacturing Infill in Topology Optimization for Improved Buckling Load
,”
Engineering
,
2
(
2
), pp.
250
257
.
54.
Clausen
,
A.
,
Andreassen
,
E.
, and
Sigmund
,
O.
,
2017
, “
Topology Optimization of 3D Shell Structures With Porous Infill
,”
Acta Mech. Sinica
,
33
(
4
), pp.
778
791
.
55.
Wang
,
C.
, and
Qian
,
X.
,
2018
, “
A Density Gradient Approach to Topology Optimization Under Design-Dependent Boundary Loading
,”
ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference
, American Society of Mechanical Engineers, pp.
V02BT03A012
.
56.
Stolpe
,
M.
, and
Svanberg
,
K.
,
2001
, “
An Alternative Interpolation Scheme for Minimum Compliance Topology Optimization
,”
Struct. Multidiscip. Optim.
,
22
(
2
), pp.
116
124
.
57.
Wang
,
C.
, and
Qian
,
X.
,
2018
, “
Heaviside Projection-Based Aggregation in Stress-Constrained Topology Optimization
,”
Int. J. Numer. Methods Eng.
,
115
(
7
), pp.
849
871
.
58.
Xu
,
S.
,
Cai
,
Y.
, and
Cheng
,
G.
,
2010
, “
Volume Preserving Nonlinear Density Filter Based on Heaviside Functions
,”
Struct. Multidiscip. Optim.
,
41
(
4
), pp.
495
505
.
59.
Eslami
,
M. R.
,
Hetnarski
,
R. B.
,
Ignaczak
,
J.
,
Noda
,
N.
,
Sumi
,
N.
, and
Tanigawa
,
Y.
,
2013
,
Theory of Elasticity and Thermal Stresses
, Vol.
197
,
Springer
,
New York
.
60.
Lazarov
,
B. S.
, and
Sigmund
,
O.
,
2011
, “
Filters in Topology Optimization Based on Helmholtz-Type Differential Equations
,”
Int. J. Numer. Methods Eng.
,
86
(
6
), pp.
765
781
.
61.
Cho
,
S.
, and
Choi
,
J.-Y.
,
2005
, “
Efficient Topology Optimization of Thermo-Elasticity Problems Using Coupled Field Adjoint Sensitivity Analysis Method
,”
Finite Elements Anal. Des.
,
41
(
15
), pp.
1481
1495
.
62.
Svanberg
,
K.
,
1987
, “
The Method of Moving Asymptotes—A New Method for Structural Optimization
,”
Int. J. Numer. Methods Eng.
,
24
(
2
), pp.
359
373
.
63.
Logg
,
A.
,
Mardal
,
K.-A.
, and
Wells
,
G.
,
2012
,
Automated Solution of Differential Equations by the Finite Element Method: The FEniCS Book
, Vol.
84
,
Springer Science & Business Media
,
Berlin
.
64.
Bruyneel
,
M.
, and
Duysinx
,
P.
,
2005
, “
Note on Topology Optimization of Continuum Structures Including Self-weight
,”
Struct. Multidiscip. Optim.
,
29
(
4
), pp.
245
256
.
65.
Zhang
,
W.
,
Yang
,
J.
,
Xu
,
Y.
, and
Gao
,
T.
,
2014
, “
Topology Optimization of Thermoelastic Structures: Mean Compliance Minimization Or Elastic Strain Energy Minimization
,”
Struct. Multidiscip. Optim.
,
49
(
3
), pp.
417
429
.
66.
ISO 11562
,
1996
,
Geometrical Product Specifications (GPS) – Surface Texture: Profile Method – Metrological Characteristics of Phase Correct Filters
,
International Organization for Standardization
,
Geneva
.
67.
ASME B46.1
,
2003
,
Surface Texture: Surface Roughness, Waviness and Lay
,
American Society of Mechanical Engineers
,
New York
.
68.
ISO 4287
,
1997
,
Geometrical Product Specifications (GPS) – Surface Texture: Profile Method – Terms, Definitions and Surface Texture Parameters
,
International Organization for Standardization
,
Geneva
.
69.
Townsend
,
A.
,
Senin
,
N.
,
Blunt
,
L.
,
Leach
,
R.
, and
Taylor
,
J.
,
2016
, “
Surface Texture Metrology for Metal Additive Manufacturing: A Review
,”
Precision Eng.
,
46
, pp.
34
47
.
You do not currently have access to this content.