nx topology optimization for designers · • works in the nx cad work part in the context of an...

NX Topology Optimization for

DesignersGuy Wills – Topology Optimization Product Manager

Unrestricted ©Siemens AG 2017

Unrestricted © Siemens AG 20182017.MM.DD Siemens PLM Software

Agenda

• Product Highlights

• Uses for Topology Optimization results

• Model Construction Opportunities

• Optimization Features

• Design Constraints

• FE Loads & Constraints

• Materials

• Optimization

• Results

• Summary


Product Highlights

• Uses a different workflow than traditional Topology Optimization solutions.

• Works in the NX CAD work part in the context of an assembly.

• Single or multiple Design Spaces. Each has it’s own:

• Construction method

• Material


• FE loads & constraints

• Optimization constraint value, eg mass target

• Model construction uses the product Functional Requirements, eg:

• Keep in/out volumes.

• Cylindrical holes with offset material around the hole.

• Counter bore holes with space for screw head, nut, socket wrench etc.

• 5mm clearance.

• Level of resolution control.

• Highly smoothed, organic shapes with sharp edges where required.


Uses for Topology Optimization Results

Topology Optimization is not the finish, for many parts

it’s just the start. Many opportunities exist to use the

Topology Optimization results.

1. Direct to AM machine for printing.

2. Direct to cast, mold or multi-axis machining.

3. Use for further Design or Simulation using

Convergent models.

4. Further Optimization work.

4. Guidance for re-modelling using traditional CAD

tools.

Holes cut into Convergent Facet model


Why Topology Optimization ?

Wikipedia… Topology Optimization is a mathematical

method that optimizes material layout within a given

design space, for a given set of loads, boundary

conditions and constraints with the goal of maximizing

the performance of the system.

Original Design

Functional Requirements

Technology that is best applied when searching for new

or improved designs based on the functional

requirements. Starting from a pre-designed model to trim

off 10% of the weight is difficult as the design is already

“optimized”, probably by hand.

Topology Optimization traces out the “load paths” that

connect between where the loads are applied and the

constraints. Keep In areas that have no loads might not

be connected by the optimizer.

Demo & Hands On Exercise

Unrestricted © Siemens AG 20182017.MM.DDPage 8 Siemens PLM Software

Topology Optimization in the Assembly Context

• Works in the NX CAD Work part in the context of an assembly.

• Enables users to reference the context geometry to:

• Build the design space shape.

• Locate connecting holes, pads, plates etc.

• Define keep-in/out geometry relative to the context

geometry.

• Define load vectors relative to the context geometry.

• Assembly components need to be

WAVE Linked to the Work Part.


Single and Multiple Design Spaces

• Single Design Space or the ability to solve the

Topology Optimization problem as a connected

assembly

• Design Space

• This is the body that encompasses a space

assigned for the Optimizer to work with.

• Scenery Body

• This is any other body connecting with

a Design Space that will transfer loads

through to a Design Space. It is not

optimized.

• Multiple Design Spaces will be solved at the same

time

Design Space

(Aluminium)

Scenery

Body

(Steel01)

Design Space

(Aluminium)

Scenery

Body

(Steel02)

Scenery

Body

(Steel01)

Design Space

(Aluminium)

Scenery

Body

(Steel02)

Scenery

Body

(Steel02)

Scenery

Body

(Steel01)

Design Space

02

(Brass)

Scenery

Body

(Steel02)

Design Space

01

(Aluminium)


Design Space

• The Design Space is the envelope that the Topology Optimization engine will

see. So to be included in the solution, the Optimization Features must lie

wholly or partially within the Design Space.

• The Design Space can be

• any Solid body (no limit on creation method)

• or a closed (water tight) Faceted body

Design Space


Manage Bodies

Bodies that are to be used as a Design

Space or for Scenery.

Bodies must exist in the Work Part.

Design Spaces



• Loads

Scenery bodies


• Loads

Table Reordering


Connections

Selecting two bodies enables the user to create

Connection between them.

Types of Connection:

• Glue (Similar to the NX Nastran Glue type)

Manage overlapping bodies

• No change to either body

• Subtract body A from body B

• EXTRUDE(12) from EXTRUDE(6)

• Subtract body B from body A

• EXTRUDE(6) from EXTRUDE(12)

EXTRUDE(12)

EXTRUDE(6)


Optimization Features

• Design Spaces and Scenery Body can have Optimization Features.

• Functional Requirements are described by the use of Optimization Features.

• Some NX modelling features are mapped to the optimization application

features. These include the following types:

• Cylinder, Block and Sphere primitives

• Copy Face

• Simple Hole

• Counter Bored Hole

• Further solid bodies (no limit on creation method) can also be added to the

Optimization Features list.

• The Design Space is the envelope that the Topology Optimization engine will

see. So to be included in the solution, the Optimization Features must lie

wholly or partially within the Design Space.



Optimization Features can describe Functional Requirements. For example:

• M8 Bolt connection that requires a clearance for a socket wrench.

• CounterBored hole feature with a hole diameter of 8mm and 30mm

diameter counter bore diameter. Counter bore length long enough to

allow socket wrench access.

• A cone shaped boss is required.

• Keep-In cylinder with draft, or cone primitive, or extruded circle with

draft, etc.

• Min of 10m clearance to avoid another component in the assembly.

• Wave Linked Body of the component with an 10mm offset for safety.

• A force is only applied to a specific part of a face.

• The face is split to define the limit of the load applied and a Copy Face

feature used to define the optimization feature.



The combination of the Design Space & the Optimization Features define

the space that the Topology Optimization has to work with.

The order of the Optimization Features list can be important. Features

below will cut through the ones above, if they intersect. Re-ordering the

Optimization Features enables the user to control which feature will cut

others.

If the Optimization Features don’t intersect,

the user has the freedom to organize as desired.

Reorder

Red block moved to

the bottom of the list


Optimization Feature – Properties

Each Optimization Feature will have properties that define it’s use in the

Topology Optimization. Some Features have fixed properties.

• Keep-In/Out

• A feature can be defined as a

• Keep-In – there must be material in that volume

during the Topology Optimization.

• Keep-Out – there must be no material in that

volume during the Topology Optimization.

• Shell – this creates a constant wall thickness

shell around the selected feature

• Counter Bored Holes are always Keep-Out.


Keep-In Optimization Feature

Any CAD body can be used as a Keep In

Optimization Feature.

This ensures the Keep In feature’s space will be

included in the final optimized model. Unless it is cut

by other optimization features.

Used to maintain connections to surrounding

components, to limit the optimizers freedom, etc.Keep In Green

Optimization

Features

These CounterBore Optimization

Features cut through the Keep In

features


Keep-Out Optimization Feature

Any CAD body can be used as a Keep Out

Optimization Feature.

A Keep Out Optimization Feature tells the optimizer

that no material can be placed in this space.

Some Optimization Features are pre-defined as Keep

Out features, these include:

• SimpleHole

• CounterBore Hole

Keep Out

CounterBore

HolesKeep Out

Block


Shell Optimization Feature

A Shell Optimization Feature is similar to the NX CAD Shell command creating

a uniformly thick offset of the body.

Offset Thickness value defines the wall thickness of the Shell.


Optimization Feature – Properties

• Offset Thickness

• To define a hole it must have material around the

hole. This is the Offset Thickness on a Hole feature.

• Offset of a solid Keep-Out body.

• Offset of Copy Face features (similar to an NX

Thicken feature).

Offset Thickness

around a solid

Keep-Out body

Offset Thickness on a

CopyFace feature

Offset Thickness on

a Hole feature


Design Constraints

Rules to guide the geometry shape during the optimization.

Design Constraints available

• Planar Symmetry

• Rotational Symmetry

• Extrude Along a Vector

• Draft

• Void Fill

• Material Spreading

• Overhand Prevention

• Self-Supporting


Design Constraints – Planar Symmetry

Planar Symmetry

• Single or dual symmetry planes.

• Only half (or quarter) Design Space required.

• Whole model returned with blending across the symmetry plane(s).

Two Symmetry Planes

Single Symmetry Plane


Design Constraints – Planar Symmetry

Global Symmetry option

• With – Model is constructed as a segment and the results are completely symmetric.

• Without – Model is constructed as a whole, and the results are as symmetric as

possible.

With “Needs Global Symmetry”

Without “Needs Global Symmetry”


Design Constraints – Rotational Symmetry

Rotational Symmetry

• Only a segment is required for the Design Space.

• Whole model returned with blending between the segments.

Stress Results


Design Constraints – Rotational Symmetry

Global Pattern option

• With – Model is constructed as a segment and the results are identically patterned.

• Without – Model is constructed as a whole, and the results are as identically

patterned as possible.

With “Needs Global Pattern”

Without “Needs Global Pattern”


Design Constraints – Extrude Along a Vector

Extrude Along a Vector

• Where possible the optimized shape will be a constant cross-section normal

to the specified vector.

• Useful for a part to be made using 2.5 axis machine tool.


Design Constraints – Draft

• Draft is applied to the model relative to an automatically located

neutral surface, relative to a plane or a collection of surfaces.

• Significant amount of time saved compared to manually

creating the draft effects.

• Repeatable allowing the user to tweak, for example, the Parting

Surfaces to get the result they need.

Surface Type = Auto

Draft vector = Hole axis

Surface Type = Plane

Draft vector = Normal to Parting Plane

Surface Type = Surfaces

Draft vector = Hole axis


Design Constraints – Draft example with Mass=35kg

Surface Type = Parting Surfaces

Draft vector = Z


Design Constraints – Draft example with Mass=15kg

Surface Type = Parting Surfaces

Draft vector = Z


Design Constraints – Void Fill

Void Fill

• Parts with interior voids will have the voids filled with wasted expensive

metal powder.

• This Design Constraint prevents internal Voids will being created or other

surfaces not directly accessible from outside the part.

Voids


Design Constraints – Material Spreading

Material Spreading

• This controls how the material is “pushed apart”.

• Have the model tend towards a hollowed out model, a thing walled model or

a strut like model.

Material

Spreading = 30%

Hollowed out

Material

Spreading = 60%

Thin Walls

Material

Spreading = 100%

Struts


Design Constraints – Overhang Prevention

Overhang Prevention

• Prevents geometry overhanging other geometry that would require support

geometry along the specified vector.

• This is important for parts built using a powder bed additive manufacturing

method. Overhanging geometry often requires supports to hold it up during the

manufacturing process. Reducing or removing the need for supports reduces

time and cost to make the part.

No Constraint

Overhang Prevention Constraint


Design Constraints – Self-Supporting

Self-Supporting

• The angle to the base plate plane, beyond which that the geometry cannot

support its self as each layer is created during the AM process. This

Constraint ensures the resultant model is not smaller than the angle.

Build

Direction

Part

Base Plate

Self-Supporting

Angle

No Constraint

Self-Supporting &

Overhang Prevention

Constraint

Build

Direction


Design Constraints – Multiple Design Constraints

• Applying multiple Design Constraints can produce interesting and

impressive results. And the order they are applied and also change the

result

• In the example shown, the Design Space will have the Planar

Symmetry applied, followed by Extrude Along a Vector. This implies

that Extrude Along a Vector takes precedence over Planar Symmetry

in the case that both cannot be satisfied.

• By selecting a Design Constraint it can be moved Up of Down thus

changing the order the Design Constraints are applied and the

resultant geometry.


Design Constraints – Per Design Space

Each Design Space can have

it’s own set of Design Constraints.

Draft

Material Spreading

Fill Void


Displacement Constraint

Displacement Constraint can be added to a Optimization

Feature in a Design Space or Scenery Body.

• Magnitude in any direction.

• Magnitude in a specific direction.

Can be used to constrain deformation of the of the model.

Max Displacement in

-Z


Load Cases

• Different combination of loads can be applied using Load Cases. For

example, front loads, side loads, top loads, etc. The solution will take all

these different load cases into account.

4x Load case examples


FE Loads

Loads are applied to Optimization

Features per Design Space and

Scenery Body.

Load types available:

• Force

• In single direction

• Pressure

• Normal to commonly applied

CopyFace

• Torque

• On a revolved feature

• Bearing Load

• On a revolved feature

• Enforced Displacement

• Along a vector


FE Constraints

Constrain to Ground are applied to

Optimization Features per Design

Space and Design Space.

Constraints available:

• Fixed

• In all directions

• Pinned

• Allowed to rotate about a vector

• Linear Slider

• Allowed to slide in one vector

• Planar Slider

• Allowed to slide in any direction

within a plane


Global Loads

Global loads are applied to the whole model.

Global Loads available:

• Acceleration

• Most commonly used to add a Gravity load for geometry that as a

significant mass that can affect the results.

• Temperature

• Used when the part will operate in an area where the temperature is

higher than the normal 20degC

• Note this requires that ALL the materials assigned to the Design

Spaces must have temperature varying properties.


Materials

• All Design Space and Scenery bodies must have a Material assigned

before Optimization.

• Any mix of Isotropic & Orthotropic material types are supported.

• Isotropic

• Material properties are the same in all directions. Most commonly

used and properties available.

• Orthotropic

• Material properties vary in X, Y, Z axis.

• Can be used to simulate parts where the properties in the Build

Direction are different to the in-layer plane.

• Orthotropic axis align with the global axis.

Demo & Hands On Exercise


Optimizations Types

Combination options of optimization Objective and Constraint:

• Compliance/stiffness based optimization

• Minimize strain energy subject to a mass target

• Stress based optimization

• Minimize mass subject to a safety factor

• Normal modes optimization

• Maximize natural frequency subject to mass target


Optimizations Types –

Minimize Strain Energy Subject to a Mass Target

Equivalent to maximize the parts stiffness whilst reducing the

mass to a target value.

• Each Design Space has it’s own Mass Target.

Top Design Space

Mass Target = 0.15kg

Btm Rgt Design Space


Btm Lft Design Space




Minimize Mass Subject to a Safety Factor

Stress based optimization to minimize the design space

volume subject to Safety Factor applied to the Yield

Stress of the material at 20degC

• Each Design Space has it’s own Safety Factor.

Top Design Space

Safety Factor = 1.1


Safety Factor = 1.0


Safety Factor = 1.2



Maximize Natural Frequency Subject to a Mass Target

Maximize the first flexible mode frequency value whilst reducing

the mass to a target value.

• Each Design Space has it’s own Mass Target.

Top Design Space







Resolution & Estimating Optimization Parameters

Resolution

• A slider bar is presented to enable the user to choose a Resolution

between “Fast & Coarse” or “Slow & Fine”.

• The value chosen by the user is important to the results as it dictates

how much detail is “carved” out of the model.

• During exploration, leaving the slider towards the Fast/Coarse end will

give good indication of what the Topology Optimization is doing.

Enabling the user to adjust/change the model setup as required.

• Once the user is happy with the model setup, then moving the slider

more to the right will generate the detail in the model.

• Manual Override enables the user to enter a specific resolution value


Resolution & Estimating Optimization Parameters

Estimate Optimization Parameters

• Based on the Resolution selected this option calculates the following

for each Design Space to guide the user:

• Approximate Design Space Mass

• Minimum Mass Target


Running the Topology Optimization

• During the Topology Optimization a first rough

pass is performed to size the problem, followed by

a second pass. This better ensures a good result.

• The Topology Optimization performance is shown

in the bar chart diagram.

• After the Optimization run the Status changes to

Meshing. This indicates the Optimization has

completed and the result (mesh) models are being

created.

• The log window reports the Optimization results

per Design Space and Scenery body.


Geometry Results

For each Design Space and Scenery body there will be 3 faceted models.

User can use the normal NX display options to control what they want to view.

Optimization results are stored as Attributes on the body

Geometry Displacement Von Mises Stress


Topology Geometry Results

• Highly smooth organic results with sharp edges were required.

• For many models no further modelling is required.

• Auto Blend can be turned off and specific Blend radii used to tighten or

smooth out connections to a Feature.


Displacement Results

The Displacement (magnitude) results are available for each Design Space

and Scenery body.

The results shown are the max values envelope across all the load cases.

The results are quantitatively good and can confidently be used to guide

design decisions.


Stress Results

The Von Mises stress results are available for each Design Space and

Scenery body.

The results shown are the max values envelope across all the load cases.

The results are quantitatively good and can confidently be used to guide

design decisions.


Natural Frequency Results

This analysis type shows just the optimized

geometry, and the Mass, Volume and Frequencies

obtained.

The results are quantitatively good and can

confidently be used to guide design decisions.


Roadmap

1. Exploring design options based on known functional requirements.

• NX Topology Optimization for Designers.

• Move current NX Open implementation into

NX Core

• More functionality

• Connection types

• Design constraints

• User selected optimization objective

and constraints

• Enable remote solves

• Include Lattice creation

• Multiple results management

• Streamline FE setup transfer to Simcenter for validation of result runs


Uses for the Topology Optimization Results

Topology Optimization is not the finish, for many parts it’s

just the start. Many opportunities exist to use the

Topology Optimization results.

1. Direct to AM machine for printing.

2. Direct to cast, mold or multi-axis machining.

3. Use for further Design or Simulation using Convergent

models.

4. Guidance for re-modelling using traditional CAD tools.

Holes cut into Convergent Facet model


Summary

• New approach to optimizing the topology within the given design

space.

• Designer for CAD users and does not require deep CAE

expertise.

• Focuses on the Functional Requirements of the design.

• Results are returned quickly.

• Highly smoothed Convergent model results

ready for AM printing, or guidance for re-design.

Guy WillsProduct Manager

Simcenter 3D Engineering Desktop

E-mail:

[email protected]

Realize innovation.

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