lattice structure optimization

Institut für Werkzeug- und FertigungstechnikProf. Dr.-Ing. S. MaderProf. Dr.-Ing. M. ReuberProf. Dr.-Ing. W. Saxler

Rheinische Fachhochschule Köln University of Applied Sciences Cologne

Lattice Structure Optimizationapplied on PolyJetting

Frankenthal, 28.06.2017E-ATC-Conference 2017

Agenda

Personal introduction

University of Applied Sciences Cologne & 3D-Printing

Lattice Structure Optimization

What is it?

How does it work?

What are the issues?

2017 June 28th Julian Gauder - Lattice Structure Optimization 2

image: www.altair.com

Personal introduction

B. Eng. Julian Gauder

2012 - apprenticeship as

Technical Product Designer

2015 - Bachelor of Engineering

in Mechanical Engineering

2015 - scientific assistant at the institute of tooling and manufacturing

technologies (iWFT) at the University of Applied Sciences RFH Köln

responsible for 3D-Printing of plastics

2015 - studying Master of Engineering in Tech. Management with focus

product development



RFH Köln gGmbH

since 1971 state-approved university of applied sciences

Supported by the “Rheinische” foundation of education

6.400 students at present

2.400 within engineering programs

3D-Printing at the RFH:

Content within lectures

CAE, Methods of Product Development, …

Application via project works


3D-Printing at the RFH Köln


providedtechnologies

FDM (2012) PolyJet (2016) SLS/SLM (2015)

examples

Purpose of purchase improve research & teaching Academic researchterms of usage free access in context of project

works & examsUsage only within research project

PolyJet technology

Operating principle is strongly related to Ink Jetting

inkjet head depositing liquid materials on print bed

material solidifies by polymerization due to exposed UV light

Resolution:

X-Y = 600 dpi; layer thickness = 16 – 32 µm

Materials:

Rigid/flexible, opaque/translucent

Advantages:

Smooth surfaces, high details,

processing multiple materials


images: 3dfabb.com

As a Reminder: Common Topology Optimization Process (TPO)

Results of a common Topology Optimization Optimized density gradient regarding boundary

conditions and load case

Problem: unequal densities within one part not producible

conventionally

Common approach: „density digitizing“: Determination of a density threshold

Elimination of volume of a density below threshold ( density = 0 %)

Apply density of 100 % on volume above threshold

Drawback by common approach: Full potential of optimization is not tapped


images: feaforall.com

1. InitialCAD Design

3. Geometry reimport

2. Topology Optimization

4. Optimized CAD Design

Lattice Structure OptimizationWhat is it?

Advancement of common Topology Optimization

no digitizing of density

Transforms density gradient into a lattice

structure

Structure cells consist out of circular beams with

different diameters

Different diameters of lattice beams are

proportional to densities

Lattice structures can represent density gradients


Lattice Structure Optimization- Phase I

LSO runs in two phases

Phase I: common Topology Optimization

Preparation of the FEA-model(boundary conditions, load case, … )

Design variable: + LSO variables

Run of Topology Optimization


FEA model containingMesh, Constraints, Force, etc.

Result of topology optimization

Lattice Structure Optimization- Phase II

Phase II: Transfer of results into lattice structure

Generation of individual lattice beams proportional to

represented density

Optimization of lattice beams

e.g. Adjusting radii at beams ends to provide

equal thickness at junction points


parameter variation

Project Work

Circumstances: Attendee of computer aided engineering lecture Recently released tool lattice structure optimization (LSO) offered topic of project work: application of LSO on 3D-PrintingObject of project work: Optimize and print cantilever with loaded force Modify parameters and analyze printabilityg


Lattice Structure Optimization- General Issues

Preparation for 3D-printing: No printable export out of hyperworks possible Separate software necessary! 3-maticSTL Import *.fem-files Transform geometries into triangular surfaces Export printable *.stl-files

Required computational performance: Enormous amount of data! Light weight structure cube: (18 mm)³ : 300 MB Optimized cantilever 100x15x15 mm³ : 1,2 GB


image: Materialise

Lattice Structure Optimization- General Issues

Visualization deviating visualization of geometry

in different software


*.fem in Hyperworks *.fem in 3matic *.stl

Lattice Structure Optimization- PolyJet Issues

Printing system‘s resolution

Layer thickness: 32 µm

Removing support material by high pressure Waterjet

Fragile beams breaking

Limited accessibility of inner structures


Lattice Structure Optimization- Conclusion & Outlook

Usability basically proven, but with given ristrictions:

Intermediate densities are representable no threshold value needed Fewer lack of optimization performance

Restricted usability Required computational performance Printing system‘s resolution Removing support material

Outlook: Usage of hydro soluble support material No breaking beams because of waterjet Better accessibility to inner structures


Image: emaze.com

Contact:Julian Gauder

0221 54687-7902@: [email protected]



Image: herb.co

mailto:[email protected]

lattice structure optimization

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