NX Topology Optimization: The Short Version
NX topology optimization means two Siemens tools. Topology Optimizer runs inside NX (Designcenter since June 2026) and returns an editable mixed convergent body for designers. Simcenter Nastran SOL 200 is the analyst’s design optimization solution sequence with solver-grade physics. inteliScience, Siemens NX and NXOpen specialists delivering nearshore from Romania, uses the first to explore and the second to defend.
| NX Topology Optimizer | Simcenter Nastran SOL 200 | |
|---|---|---|
| Where it runs | Task environment inside the NX part (Designcenter 2606, June 2026) | Simcenter Nastran solver, set up from Simcenter 3D (2606, July 2026) or Femap |
| Who uses it | The designer, in the part they own | The CAE analyst, in a FEM/SIM file pair |
| Inputs | Design space, keep-in and keep-out, loads, boundary conditions, Max Mass, shape constraints such as planar symmetry | Meshed design region, objective (compliance, weight), mass fraction, static and dynamic load cases |
| Result type | Mixed convergent body (mesh plus analytic faces), an associative design feature | Element density per design cycle, exported as STL facets into modeling |
| Validation | Not included; a separate structural solve is required | Solver-native; the rebuilt CAD part still needs its own analysis |
| Licensing | Quoted by Siemens, no public list price | Quoted by Siemens, no public list price |
The Problem: The Organic Result Looks Finished
A Topology Optimizer screenshot looks like a released part. It is a density field with a skin. Send that body to CAM or to the powder-bed printer without a rebuild and a verification solve, and every undercut, every 0.4 mm strut and every unblended keep-out edge becomes your problem on the shop floor.
Siemens has been careful with its own wording. The March 2022 what’s-new post describes Topology Optimizer as an application that “uses functional requirements to determine an optimized structural form” and delivers “a mixed convergent body” you can edit. Nowhere does it say the result has been validated against your load case in a certified solver. That step belongs to Simcenter, and Siemens sells it separately for a reason.
The confusion we meet in DACH machine builders: one team has the CAD module, another has the Nastran license, and nobody has written down which result counts. This post is that decision.
How Topology Optimizer Works Inside NX
Topology Optimizer is a task environment inside the NX part, driven from the Optimization Navigator. You define a design space, mark keep-in and keep-out regions, apply loads and boundary conditions, set a mass limit, add shape constraints, and solve. The result is a mixed convergent body that sits in the Part Navigator like any other feature and updates associatively.
The sequence, as Siemens documents it in the two-part Tips and Tricks series (May 2023, on the December 2022 release):
- Start the Topology Optimization command; it opens the task environment.
- Create the design space and select the material that may be used.
- Select the keep-in and keep-out areas. Siemens calls this “essential to the validity of the study”. Bolt bosses, mating faces and clearance volumes go in before any load.
- Apply loads and constraints (structural or vibrational) and pin the bolted regions.
- Under Optimization Constraint, set Max Mass (the Siemens example reduces it to 0.8 kg) and move the Solution Balance slider between Speed and Accuracy.
- Add a Shape Constraint for symmetry (name it, pick two faces), or Fill From Direction for a mould-friendly shape.
- Clone the study for a second mass target, then switch Results Settings from Single Study Report to Study Comparison.
The June 2024 release added a live Preview during the solve, an automatic transition blend at the design-space boundary, and Multi-Axis Tooling for 5-axis milling. The June 2026 release (Designcenter 2606, the first under the new name) did not headline topology; Siemens listed it among capabilities added “in previous years”.
Our position: it is the best concept tool a designer has inside NX, and it is not a solver. We treat every Optimizer result as a shape proposal with a mass number attached, never as evidence.
How Simcenter Nastran SOL 200 Works
SOL 200 is the design sensitivity and optimization solution sequence of Simcenter Nastran. Siemens describes it as a solution that lets the user “vary the model parameters to minimize an objective function, such as overall weight, given constraints on both the static and dynamic response.” Sizing and shape optimization have lived there for decades; topology optimization arrived with Simcenter 3D 12 in October 2017 as “our new NX Nastran SOL 200 topology optimization solution.”
The workflow is an analyst’s workflow. In Simcenter 3D you mesh the part, define the optimization area (the Siemens tutorial excludes the screw holes), pick the solution type “SOL 200 Topology Optimization”, set objective and mass fraction, and solve. The tutorial bracket lands on design cycle 35 and “minimizes the compliance of the bracket while using only 10-30% of the original weight.” The result is a density per element; to get it into CAD you export STL facets and import them into modeling.
Two consequences follow. The physics is the solver’s physics: the same Nastran that runs your statics and modal removed the material. And there is no associative feature. The STL is a snapshot; change a bolt pattern in CAD and you re-mesh, re-run and re-import.
Simcenter 3D 2606 shipped in July 2026 (“Simcenter 3D 2606 is Out Now!”, 22 July 2026). The notes concentrate on SOL 401 contact convergence rather than SOL 200, which tells you how mature the optimization sequence is: infrastructure, not a headline.
Where the Two Differ in Practice
The gap is where the result lives, what physics produced it, and how many times you can afford to iterate.
| Criterion | NX Topology Optimizer | Simcenter Nastran SOL 200 |
|---|---|---|
| Physics behind the shape | Built-in, structural and vibrational loads, Speed vs Accuracy slider | Full Nastran load cases, static and dynamic response |
| Ownership of the result | Associative feature in the CAD part | Density field in the SIM file; STL snapshot in CAD |
| Iteration cost | Minutes per study, cloneable, Study Comparison | Mesh, design cycles, export, import: hours per loop |
| Manufacturing shaping | Shape constraints (symmetry, fill direction, multi-axis tooling) | Optimization area and constraints on the FE model |
| Evidence for a release review | None on its own | The run is a Nastran run; the rebuilt part still needs analysis |
| Who signs it off | Design lead | Simulation lead |
We will not mill Optimizer mesh as-is, and we will not hand a designer a SOL 200 STL and call it a model. Either path ends in a rebuilt parametric part with a verification solve on it. The tools differ in how expensive it is to get there and how much evidence you hold when you arrive.
When the CAD Feature Is Enough
Run Topology Optimizer alone when the part is a bracket, lever, clamp or housing rib, the loads are static, the failure mode is stiffness rather than fatigue, and the review accepts a CAD-side verification solve. Escalate to SOL 200 for dynamic loads, a solver named in the specification, or an optimization that itself has to be defended.
Three cases we have sat in:
Machine-frame bracket, static load, aluminium. Topology Optimizer, three cloned studies at different Max Mass values, Study Comparison, rebuild, linear static check. SOL 200 would add a week and no information the reviewer asked for.
Rotating carrier with a modal requirement. SOL 200. The first eigenfrequency is a dynamic constraint, and the Optimizer’s vibrational load is not a constrained modal optimization in Nastran. The analyst owns the design region; the designer rebuilds from the STL.
Casting where the foundry has veto rights. Topology Optimizer with Fill From Direction and planar symmetry, because the manufacturing constraint matters more than the last percent of mass. Verification afterwards in the solver the foundry’s customer trusts.
If your designers have never opened the task environment, that is a training question before it is a licensing question. Our Siemens NX training covers the Optimizer inputs, the keep-out discipline and the rebuild.
From Organic Result to a Manufacturable Part
The rebuild is the real work. Whether the source is a mixed convergent body or an imported STL, the path is the same: keep the facet body as a reference, model the analytic faces the machinist needs, rebuild the organic members, and run a verification solve on the parametric part.
In NX that means Convergent Modeling. The mixed convergent body already carries analytic faces where the keep-ins were, so bores and mating faces are precise; the struts between them are facets. We rebuild those with ordinary features (swept sections, blends with a real radius), check draft and tool access, then suppress the optimizer feature and keep it in the tree for the next iteration.
Before the rebuild starts we want to know what is actually in the part. This journal lists the bodies in the work part and prints the feature types, so you can see whether the optimizer feature committed:
# NXOpen Python journal, Designcenter 2606.
# Lists every body in the work part, then prints the feature types.
# A Topology Optimizer result is a mixed convergent body: NXOpen reports it
# as a Body, so the feature tree is the reliable place to check for it.
import NXOpen
session = NXOpen.Session.GetSession()
work_part = session.Parts.Work
listing = session.ListingWindow
listing.Open()
body_count = 0
for body in work_part.Bodies:
body_count += 1
listing.WriteLine("Body: " + body.Name + " [" + body.JournalIdentifier + "]")
listing.WriteLine("Bodies in work part: " + str(body_count))
# Print all feature types; look for the topology optimization entry.
# If it is missing, the study never committed a result.
for feature in work_part.Features:
listing.WriteLine(feature.FeatureType + " " + feature.GetFeatureName())One body with the block’s original name and no optimization entry means the study did not commit; check the license and the design-space selection. Once the tree looks right, the same script seeds a check-in rule: no optimizer feature may stay unsuppressed in a released part. The step from journal to compiled add-in is covered in NX journal vs NXOpen.
The verification solve closes the loop: same loads, same constraints, on the rebuilt body, in the solver the reviewer accepts. A part that was optimised and never re-analysed is a sculpture with a mass number.
This runs as a POC. What’s missing for production: keep-out discipline, a rebuild standard, a verification solve in the solver your reviewer accepts, and a check-in rule that stops organic bodies from being released. We close the gap from “the Optimizer produced a shape” to “the shop accepted the part” as one service: NX CAD design services.
What to Look For Before You Commit to Either Path
Five checks, in the order we run them on a new part.
- Load type. Static only: Topology Optimizer is enough. Modal, frequency response or fatigue: SOL 200.
- Keep-outs written down. Bolt bosses, mating faces, tool paths, clearance volumes. Missing keep-outs are the most common reason an Optimizer result is thrown away.
- Manufacturing shape constraint. Symmetry, fill direction or multi-axis tooling in the Optimizer; the optimization area in SOL 200. Pick it before the first solve.
- Rebuild owner. Name the person who models the parametric part and budget the hours; it takes longer than the optimization run.
- Verification solver. Whichever tool the release review accepts. Write it into the brief, and automate the check that no unsuppressed optimizer feature reaches Teamcenter: a routine win under Siemens NX automation, with the API side in our NX API programming overview.
One thing we ask engineering leads to stop doing: treating Designcenter Copilot as an optimizer. Siemens describes Copilot as guidance drawn from the documentation. It will tell you where the Topology Optimization command sits. It does not run the study.
Frequently Asked Questions
What is NX topology optimization?
It is the Topology Optimizer application inside NX (Designcenter since June 2026). You define a design space, keep-in and keep-out regions, loads, boundary conditions and a Max Mass; the optimizer returns a mixed convergent body (mesh plus precise analytic faces) that behaves like an associative design feature. It is a concept tool for designers, not a certified solver.
NX Topology Optimizer vs Simcenter Nastran SOL 200: which should we use?
Topology Optimizer for exploring shape inside the CAD part, with cloned studies and Study Comparison in minutes. SOL 200 when the optimization must carry solver-grade evidence: dynamic constraints, a solver named in the specification, or a reviewer who wants the Nastran run. Both paths end in a rebuilt part with a verification solve.
Can I 3D-print the Topology Optimizer result directly?
For a display model, yes. For a functional part we rebuild first: minimum strut thickness, overhang and support removal are not checked by the optimizer, and no structural verification has run on the printed geometry.
How much does NX topology optimization cost?
Both Topology Optimizer and Simcenter Nastran are quoted by Siemens through resellers; there is no public list price for either. In project budgets the module fee is rarely the largest line. The rebuild hours and the verification solve are. Plan those before you plan the license.
Does the Topology Optimizer result stay associative?
Yes. Siemens describes the result as an optimized feature that “is no different to any other design feature” with “all the associative update benefits.” Change the design space or a keep-out and the feature updates. A SOL 200 result imported as STL does not update; you re-run and re-import.
Next Step
Want topology optimization in NX without shipping sculpture to the shop floor? A free 60-minute call with our NX engineers (nearshore from Romania, EET = CET+1) maps which parts belong in the Optimizer, which need SOL 200, and who owns the rebuild. Book a strategy call about NX topology optimization
Related Topics
- NX CAD design services
- Part family, WAVE or NXOpen for variants
- NX Sheet Metal or Solid Edge for enclosures
References
- Siemens Designcenter blog, “Designcenter: a new name for the future of engineering”, 26 June 2026: https://blogs.sw.siemens.com/designcenter/designcenter-a-new-name-for-the-future-of-engineering/ (retrieved 24 September 2026)
- Siemens Simcenter blog, “What’s new in Simcenter 3D 2606”, 22 July 2026: https://blogs.sw.siemens.com/simcenter/whats-new-in-simcenter-3d-2606/ (retrieved 24 September 2026)
- Siemens NX Design blog, “What’s New in NX | Intelligence Driven Design: Topology Optimization”, 17 March 2022: https://blogs.sw.siemens.com/nx-design/whats-new-in-nx-intelligence-driven-design-topology-optimization/ (retrieved 24 September 2026)
- Siemens Designcenter blog, “Topology Optimization: Part One | NX Tips and Tricks”, 2 May 2023: https://blogs.sw.siemens.com/designcenter/topology-optimization-nx-tips-tricks/ (retrieved 24 September 2026)
- Siemens NX Design blog, “NX | Tips and Tricks | Topology Optimization part 2”, 12 May 2023: https://blogs.sw.siemens.com/nx-design/topology-optimization-part-2-nx/ (retrieved 24 September 2026)
- Siemens NX Design blog, “What’s new in NX | Jun 2024 | AI-enabled & Generative Design”, 10 July 2024: https://blogs.sw.siemens.com/nx-design/new-nx-jun-2024-generative-design/ (retrieved 24 September 2026)
- Siemens Simcenter blog, “Simcenter 3D 12: Simulation to Drive Design Direction”, 30 October 2017: https://blogs.sw.siemens.com/simcenter/simcenter-3d-12-simulation-to-drive-design-direction/ (retrieved 24 September 2026)
- Siemens Simcenter 3D documentation, tutorial “Using topology optimization” (SOL 200 Topology Optimization): https://docs.sw.siemens.com/documentation/external/PL20190701133928562/en-US/sc3d_2019_1_tutorials/content/default/1.0/sc3d_2019_1_tutorials/en_US/tutorials_prepost/tutorials_prepost/using_topology_optimization.html (retrieved 24 September 2026)
- Siemens Xcelerator Academy, course description “Design Sensitivity and Optimization with Simcenter Pre/Post”: https://training.plm.automation.siemens.com/ilt/iltdescription.cfm?pID=NXNAS331______NAS__12.0___5000 (retrieved 24 September 2026)
- Siemens, Simcenter Nastran product page (optimization capabilities): https://www.siemens.com/en-us/products/simcenter/mechanical-simulation/nastran/ (retrieved 24 September 2026)
- Siemens Designcenter blog, “Designcenter X NX | Tips and Tricks | Copilot”, 12 May 2026: https://blogs.sw.siemens.com/designcenter/designcenter-x-nx-tips-and-tricks-copilot/ (retrieved 24 September 2026)