desktop engineering - design freedom with new constraints

7/25/2019 Desktop Engineering - Design Freedom With New Constraints

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Focus on Lightweighting ///3D Printing

22 DE| Technology for Optimal Design Engineering January 2016 ///deskeng.com

The dynamic duo of 3D printingand new optimization softwareis giving engineers the freedom

to design and produce organic shapesand lightweight structures that raisethe bar on ingenuity while deliver-ing unprecedented savings. Yet tofully reap the benefits of this nicelymatched pair, engineers need to mas-ter a set of new constraints to ensuredesigns can be produced in a reliable,cost-effective fashion.

Advances in 3D printing technol-ogy from new materials to higherresolution output capabilities cou-pled with topology optimization andother design software improvementsare empowering engineers to comeup with freeform shapes and complexlattice structures that challenge con-ventional design limitations. Thesenext-generation designs are not only

vi sual ly compel ling , they are typi-cally more aerodynamic, weigh lessand boast fewer parts than designscrafted with traditional CAD toolsfor output using mainstream manu-facturing practices.

While traditional boundaries dontnecessarily apply in the world of 3Dprinting, engineers expecting an un-fettered design environment will bein for a surprise. In general, the talkabout 3D printing technology de-

livering design freedom without theconstraints of traditional manufac-

turing is true, for the most part, saysTim Thel lin, di rector of Softwareand Productivity Tools for StratasysDirect Manufacturing. If you knowyoure building a part with an addi-tive manufacturing process, you donthave to worry about undercuts, filletsor internal channels that go deep in-side the part. Yet there are differentconstraints driven by the technology

youre using and the materials you arebuilding with.

Out With the Old,In With the NewFor many 3D printing or additivemanufacturing (AM) technologies,the biggest constraint is optimiz-ing designs to minimize or eliminatesupport structures needed during theactual build process. With certainAM techno logies , spec if ical ly Di -rect Metal Laser Sintering (DMLS),

there are structural checks to ensurethe technology used to build up the

Design Freedomwith New ConstraintsThe marriage o 3D printing and optimization sofware is giving riseto a new generation o lighter, visually compelling designs butnot without constraints.BY BETH STACKPOLE

Stratasys Direct Manufacturings Direct Metal Laser Sintering (DMLS)

offerings are helping optimize structures for aerospace applications, including

this lighter weight bracketed part.Image courtesy of Stratasys.


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deskeng.com ///January 2016 DE| Technology for Optimal Design Engineering23

part doesnt actually create stressesthat result in part deformation, andultimately, a bad build. Optimizing adesign for the materials used or forproper orientation on the build plat-

form are other factors that need tobe considered early on in the process,and there are myriad other constraintsthat may seem foreign to engineers ac-climated to traditional manufacturingprocesses like casting, injection mold-ing and stamping, experts say.

Design for 3D printing is stillin early adulthood, notes CraigTh er ri en, se ni or pr od uc t po rt fo -lio manager at Dassault SystmesSOLIDWORKS. People think that

a 3D-printed part will have the sameproperties as a casted or forged part,

but it doesnt. Because 3D printinginstills different mechanical propertieson a part, it is not an exact science, andTherrien says many engineers com-pensate by overdesigning the part in

the hopes of adding rigidity a tacticthat minimizes the lightweighting ad-vantages that make 3D printing such adraw in the first place.

Support structures, in particu-lar, seem to present the biggest de-sign challenges to customers, saysEric Utley, applications specialist atProto Labs, a digital manufacturingsource for custom prototypes andlow-volume production parts. Com-monly used in AM processes, espe-

cially metal technologies, supportsare typically scaffold or lattice-type

structures required at certain anglesto hold a part up as the detailed fea-tures are being built. Designing a partso that it steps up incrementally andcan be self supporting (instead of fea-

turing long bridges or overhangs) issomething engineers untrained in 3Dprinting techniques dont necessarilyunderstand, Utley says.

Likewise, untrained engineers maydesign parts with volumes that inad-vertently trap powder material fromthe 3D printing process or have sup-ports that are difficult, if not impossi-ble, to remove. These constraints arecommonplace with organic shapes andwith metal AM practices, Utley says.

Education and consulting services arekey, he says. You need to think about

Altairs topology optimization software has a symbiosis with additive manufacturing, maximizing design freedom to

create complex, freeform bionic structures. Image courtesy of Renishaw.


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Focus on Lightweighting ///3D Printing

24 DE| Technology for Optimal Design Engineering January 2016 ///deskeng.com

support structures as youre designing.You need to consider what material youwant and then look at which 3D print-ing technology builds in that material.Next you figure out the limitations anddesign around it. Its going to be differ-ent for each of the 3D printing tech-nologies in terms of what can get byand what cant, Utley explains.

Designs that prevent easy sup-

port removal, build orientations thatdont work within the build plat-form, trapped volumes, and issuessurrounding wall thicknesses are thebiggest mistakes made by BasTechcustomers, notes Scott Young, engi-neering manager for the company,which provides AM services. Helpingcustomers work around these inher-ent design flaws isnt the problem,Young says, but companies would bebetter served addressing the issuesat the onset of design to avoid addi-tional costs. It would make life a loteasier and less costly in the end, hesays. If designers understand thingsupfront, we can optimize the processand everything goes more smoothly.

Companies like GE Aviation andAlcoa, which are investing millions of

dollars to ramp up their internal AMexpertise and perfect 3D printing ex-pertise, are already seeing results. Inone of the more highly touted exam-ples, GE completely redesigned its fuelnozzles (19 of them to be exact) on itsLEAP engine for Direct Metal LaserMelting (DMLM) processes using EOSsystems. The result is a nozzle that isnow a single part instead of 20 partsmachined together, and its far stron-ger than its predecessor made with

traditional subtractive manufacturingprocesses. You have to leave behind

conventional thoughts and structureswhen you think in terms of design-ing for AM, says Andy Snow, seniorvice president of EOS North America,which offers consulting services in howto design for its AM technology.

Software to the Rescue

In recognition of the skills gap, de-sign tool makers 3D printer manu-facturers, and simulation softwareproviders are stepping up efforts toprovide new services and products tomake it easier to design for AM muchlike any design for manufacturabilityeffort. Stratasys Direct Manufactur-ing, for example, leverages the Insightsoftware, which automatically s licesmodels to generate support struc-tures and material extrusion pathswhile also allowing engineers to opti-mize build orientation for maximumstrength. Stratasys Fused DepositionModeling (FDM) technology also al-lows for sparse fills, a way to printout hollowed or partially filled mod-els optimized to meet cost and weightreduction targets, Thellin says.

Theres lots of activity on the CADand simulation front. Altairs topol-ogy optimization tools, Inspire from

solidThinking Inc. and OptiStruct, areinstrumental for creating the organicshapes that AM practices enable, ac-cording to Ming Zhou, Altairs seniorvice president of FEA (finite elementanalysis) and Optimization. To helpengineers effectively integrate topol-ogy optimization into the early AMdesign process, Altair has partneredwith Materialise to offer its 3-maticSTL software to HyperWorks users,allowing them to make design modifi-

cations directly on STL, scanned andCAD data in preparation for 3D print-

Stratasys sparse ll capabilities

for its Fused Deposition Modeling

(FDM) technology create a

honeycomb structure critical

for lightweighting parts andaccelerating build times.Image

courtesy of Stratasys.

Toshiba PrototypesMetal 3D Printer

Toshiba Machine, a subsidiary

of Toshiba, has become the

latest additive manufacturing

(AM) outsider to announce it will be

moving into the 3D printing arena.

It already has a working prototype

and claims it will be ready for a 2017

launch date.

The company is staking its claim

in AM through speed. It has devel-

oped a metal printing process it

calls laser metal deposition, which

uses a laser in tandem with pow-

dered material deposition to build

layers. Thats pretty standard as

far as metal printing processes go,

but Toshiba Machine claims its pro-

totype is over 10 times faster thanexisting AM systems.


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deskeng.com ///January 2016 DE| Technology for Optimal Design Engineering25

ing. Moving forward, Zhou says Altairis working to evolve its optimizationalgorithms to consider overhang angleconstraints, supports and print orien-

tation, as well as simulation of print-ing processes to analyze thermal andmaterial effects. Were trying to bringadditional cost components into opti-mization, he says.

Two of this years major CAD re-leases, Autodesk Inventor 2016 andSOLIDWORKS 2016, also featureadvances aimed at simplifying de-sign for 3D printing. For example,Autodesk Inventor 2016 and Fusion360 include 3D Print Studio, a dedi-

cated 3D printing environment thatlets users optimize model orientation(even split it in two) for a variety ofsupported 3D printers. Autodesk alsohas a lot going on in the area of to-pology optimization as part of its vi-sion for what it calls generative de-sign the concept of starting witha goal and exploring all the possiblepermutations of the solution until thebest one is found. Shape Generator,available in the latest Inventor up-date, is a topology optimization func-tion embedded directly in the CADenvironment, and Autodesk Within,which automatically generates latticestructures that fit user-defined vol-umes, is being specifically positionedto help optimize designs for AM.

SOLIDWORKS 2016 now fea-tures the Print3D Property ManagerSettings tab that enables engineers tochange model scale or reorient mod-

els to fit in a build volume. A pre-view tab also lets users run a previewanalysis to identify faces that requiresupports during 3D printing, and thesoftware will display striation linesresulting from layering so users candetermine whether the print resolu-tion is optimized enough for the de-sired output, according to Therrien.

Beyond these capabilities, Therriensees simulation software evolving tohelp engineers check the function of a

3D-printed part much like they do nowfor an injection molded part. One of

the next steps is verifying what we aremaking because 3D printing is repeat-able, he says. Thats something thatwill come in the future.

One company looking to the fu-ture of AM is 3DSim. The startup isleveraging years of research work inAM along with supercomputing ca-pabilities to provide fast and action-able insight into metal 3D printingprocesses. The idea, according toCEO Brent Stucker, is to help or-ganizations eliminate the waste andreduce the costs of AM practices bypredicting residual stress and strain,minimizing the amount of supportmaterials and post-processing finish-ing work. ExaSim, targeted for release

in the second half of 2016, is a wholenew set of simulation tools targeted atthe machine operator and designed asa guide for helping them build a partproperly. The software, which willrun in the cloud, takes some of themystery out of 3D printing processes.

It takes a long time for someone tolearn the physics of whats going on,Stucker explains. Every time you putnew geometry on a new machine andcreate a new scan pattern or vector,

you produce a different microstructureand you cant treat it as a black box.

With ExaSim, Stucker is trying toturn what seems like a random processinto something repeatable. Peoplespend a lot of time on trial and errorexperiments to try to satisfy their cu-riosity or to get a part qualified, hesays. Were trying to achieve a dra-matic reduction in that time. DE

Beth Stackpoleis a contributing edi-tor to DE. You can reach her at [email protected].

INFO3DSim: 3DSim.com

Altair: Altair.com

Autodesk: Autodesk.com

BasTech: BasTech.com

EOS North America: EOS.info

Materialise: Materialise.com

Proto Labs: ProtoLabs.com

solidThinking: solidThinking.com

SOLIDWORKS: SOLIDWORKS.com

Stratasys Direct Manufacturing:

StratasysDirect.com

Toshiba Machine: Toshiba-

Machine.com

For more information on this topic,visit deskeng.com.

SOLIDWORKS 2016s Print3D PropertyManager Settings tab includes the

ability to change the model scale and to reorient the model to ft the print

volume. Image courtesy of SOLIDWORKS.

desktop engineering - design freedom with new constraints

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