Topology optimization considering overhang constraints: Eliminating sacrificial support material in additive manufacturing through design

Gaynor, Andrew T.; Guest, James K.

doi:10.1007/s00158-016-1551-x

Cited by 383 publications

(193 citation statements)

References 35 publications

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“…However, this required the introduction of several additional parameters and constraint aggregation, resulting in some constraint violations. Therefore in this work, α oh will be enforced implicitly through a filter, as has been done for the overhang constraints in Gaynor and Guest (2016) and Langelaar (2017). The filter will be integrated in a density based topology optimization (Bendsoe and Sigmund 2003).…”

Section: Integration In Topology Optimizationmentioning

confidence: 99%

“…They proposed a methodology to measure the overhang angle for evolutionary topology optimization, but this method has not been implemented. The first actual implementation was done by Gaynor et al (2014), detailed in Gaynor and Guest (2016). A wedge shaped filter in combination with Heaviside projection was used to obtain self-supporting topologies.…”

Section: Introductionmentioning

confidence: 99%

“…However, the filter is only applicable to rectangular structured meshes, and α oh can only be tuned by changing the element aspect ratio. Both (Gaynor and Guest 2016) and (Langelaar 2016(Langelaar , 2017 evaluate the manufacturability in a global sense, following the layer by layer fashion of the manufacturing process. Other methods, that only constrain the overhang angle locally, have also been presented.…”

Section: Introductionmentioning

confidence: 99%

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Continuous front propagation-based overhang control for topology optimization with additive manufacturing

Ven

Maas²,

Ayas

et al. 2018

Struct Multidisc Optim

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Additive manufacturing enables the nearly uncompromised production of optimized topologies. However, due to the overhang limitation, some designs require a large number of supporting structures to enable manufacturing. Because these supports are costly to build and difficult to remove, it is desirable to find alternative designs that do not require support. In this work, a filter is presented that suppresses non-manufacturable regions within the topology optimization loop, resulting in designs that can be manufactured without the need for supports. The filter is based on front propagation, can be evaluated efficiently, and adjoint sensitivities are calculated with almost no additional computational cost. The filter can be applied also to unstructured meshes and the permissible degree of overhang can be freely chosen. The method is demonstrated on several compliance minimization problems in which its computational efficiency and flexibility are shown. The current applications are in 2D, and the proposed method is readily extensible to 3D.

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Section: Integration In Topology Optimizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Continuous front propagation-based overhang control for topology optimization with additive manufacturing

Ven

Maas²,

Ayas

et al. 2018

Struct Multidisc Optim

View full text Add to dashboard Cite

show abstract

“…Recently, significant process has been made in this direction, by TO procedures that include overhang restrictions in 2D (Langelaar 2017;Gaynor and Guest 2016; Van de Ven et al 2017) and 3D (Langelaar 2016b;Qian 2017;Hoffarth et al 2017). With these procedures, fully printable part geometries can be generated that require no additional supports for overhanging regions.…”

Section: Introductionmentioning

confidence: 99%

Combined optimization of part topology, support structure layout and build orientation for additive manufacturing

Langelaar

2018

Struct Multidisc Optim

128

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Additive manufacturing (AM) enables the fabrication of parts of unprecedented complexity. Dedicated topology optimization approaches, that account for specific AM restrictions, are instrumental in fully exploiting this capability. In popular powder-bed-based AM processes, the critical overhang angle of downward facing surfaces limits printability of parts. This can be addressed by changing build orientation, part adaptation, or addition of sacrificial support structures. Thus far, each of these measures have been studied separately and applied sequentially, which leads to suboptimal solutions or excessive computation cost. This paper presents and studies, based on 2D test problems, an approach enabling simultaneous optimization of part geometry, support layout and build orientation. This allows designers to find a rational tradeoff between manufacturing cost and part performance. The relative computational cost of the approach is modest, and in numerical tests it consistently obtains high quality solutions.

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“…For additive manufacturing (AM), Brackett et al [33] summarized the issues for the application of topology optimization in AM. Leary et al [34] proposed a method in which the obtained optimal configurations are modified to satisfy an overhang constraint required to avoid the use of support material in AM, and additional schemes for imposing overhang constraints during the optimization procedure have been proposed [35,36]. Li et al [37] proposed a connectivity constraint to avoid enclosed voids in structures by introducing a virtual scalar field.…”

Section: Introductionmentioning

confidence: 99%

Manufacturability evaluation for molded parts using fictitious physical models, and its application in topology optimization

Sato

Yamada

Izui

et al. 2017

Int J Adv Manuf Technol

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Manufacturing methods using molds, such as casting and injection molding, are widely used in industries. A basic requirement when using such manufacturing methods is that design engineers must design products so that they incorporate certain geometrical features that allow the mold parts to be removed from the created solid object. In the present study, we propose a manufacturability evaluation method especially adapted for the use of molds. To evaluate the manufacturability, we introduce fictitious physical models that are described by steady-state anisotropic advectiondiffusion equations. In these fictitious physical models, material domains have a virtual source term and the advection directions are aligned with the directions along which the mold parts are parted. Void regions, where the values of all fictitious physical fields are high, then represent either undercut geometries that would prevent the mold from being released, or interior voids that cannot be cast. Consequently, manufacturability can be evaluated using these fictitious physical fields. Furthermore, in the present study, we integrate this evaluation method with topology optimization and propose a scheme for imposing a molding constraint within the topology optimization procedure. This newly proposed topology optimization method can consider the position of mold parting lines prior to the detailed optimization procedure. Several numerical examples are provided to demonstrate the validity and effectiveness of the proposed method.

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Topology optimization considering overhang constraints: Eliminating sacrificial support material in additive manufacturing through design

Cited by 383 publications

References 35 publications

Continuous front propagation-based overhang control for topology optimization with additive manufacturing

Continuous front propagation-based overhang control for topology optimization with additive manufacturing

Combined optimization of part topology, support structure layout and build orientation for additive manufacturing

Manufacturability evaluation for molded parts using fictitious physical models, and its application in topology optimization

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