Project examples - Software and simulation

Final surface roughness and porosity is influenced by the homogeneity of the individual powder-bed layers.

Discrete-element-simulations enable in-depth analyses the powder spreading process.

Influencing values like powder properties and processing parameters on part properties can be investigated.

Numerical simulations can replace cumbersome experimental test series to determine optimal processing parameters.

Simulations are performed using the comprehensive software package SimPARTIX.

Link: 

http://www.simpartix.de/

Contact: 

Fraunhofer IWM, Dr. Claas Bierwisch, claas.bierwisch@iwm.fraunhofer.de, +49 761 5142 347

Graded or multi-material parts made out of ceramic and/or metal exhibit inhomogeneous shrinkage during final sintering

Depending on material and part geometry this results in an unwanted distortion and leads to deviations from the desired final part shape

By using detailed sinter models the necessary geometric adjustments can be predicted in advance and thus compensated in the AM building process

The printed green part will then shrink exactly to the desired target shape

By numerical simulation extensive experimental test series to determine the optimal printing geometry and process parameters will be avoided

In the calculations self-developed material routines are used in combination with commercial finite element programs

Contact: 

Dr. Torsten Kraft, torsten.kraft@iwm.fraunhofer.de, +49 761 5142 248

Cuttlefish locally controls the process parameters (e.g. laser power in the SLM process) and material positioning (e.g. material distribution in high-resolution multi-material 3D printing) to optimally reproduce given designs with annotated optical or mechanical properties taking into account machine and material limitations. The driver is modular and can be adapted to various 3D printing technologies such as FDM, Polyjetting, DLP, SLA or SLM by reusing components. The streaming capability allows printing while the calculation is still running.

One of the focal points of the developments is in the field of graphic multi-material 3D printing with the aim of reproducing not only the geometry of an object but also its optical material properties or so-called visual attributes (colour, gloss, translucency). Applications can be found in almost all industries where design prototypes are needed (especially in automotive, film, furniture, etc.), as well as for spare parts that have to be integrated into a visual environment (e.g. cosmetic eye replacement). In these cases the accurate reproduction of given/measured optical material properties is an important, if not decisive criterion for the application.

Cuttlefish makes it possible to print very complex designs, which can consist of many overlapping parts with annotated locally variable properties. 

In the completed EU-project »SIMCHAIN« a simulation chain was developed that allows to study the influence of process parameter on the local mechanical properties of additive manufactured parts.

The material strength and stiffness are calculated based on the local microstructure.

In the project the simulation chain was applied to the SEBM-process (Selective Electron Beam Melting ).

Project: 

»SIMCHAIN« (Clean Sky Joint Undertaken, Grant No. 326020)

Contact: 

Dr. Dirk Helm, dirk.helm@iwm.fraunhofer.de, +49 761 5142 158

Resins for stereolithography shrink during polymerization. During the layer wise curing this leads to residual stresses and warpage.

The amount of residual stress depends on a complex interplay of shrinking, increasing stiffness, decreasing flowability and the shape of the component during polymerization.

The mechanical properties of curing resins can be analyzed at the Fraunhofer IWM experimentally. The results can be conveyed into a material model that help to predict the residual stresses and the warpage.

As the model takes the kinetics into account different types of resins as well as different process parameters can be assessed and optimized.

Projects: 

SimGen (FhG)

Publication: 

C. Koplin, M. Gurr, R. Kübler, R. Mülhaupt, R. Jaeger, Formgenauigkeit in der Stereolithographie, Konstruktion, (2009), 11/12,  p. IW11-IW12

Contact:  

Dr. Raimund Jaeger, raimund.jaeger@iwm.fraunhofer.de, +49 761 5142 284

In the completed project »Bionic manufacturing« (01RB0906A) scientists from Fraunhofer IWM developed software that creates lightweight constructions by microstructuring bulk designs.

The conformity of the microstructure allows a beforehand calculation of mechanical properties like strength and stiffness.

To optimize the efficiency of the design, the microstructure can be adapted to a given load situation.

This adaptation happens by a local increase of selected struts.

The resulting cellular structure can be manufactured by different additive manufacturing processes.

The cantilever chair »Cellular Loop« was developed and manufactured as a demonstrator. 

Project:

Bionic manufacturing, supported by the German Federal Ministry of Education and Research under grant (01RB0906A)

Publication: 

https://doi.org/10.1007/s00170-016-9615-z, https://dx.doi.org/10.1002/bate.201300091

Pending:

A German patent has been granted (DE 102012203869 A1)

Contact: 

Dr. Jörg Lienhard, joerg.lienhard@iwm.fraunhofer.de, +49 761 5142 339