Software and simulation

Project examples of the research topic Software and simulation

© Fraunhofer IWM

Optimization of shape distortions

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

© Fraunhofer IWM

Local properties of additive manufactured parts

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.

© Fraunhofer IWM

Simulation of residual stresses and warpage in stereolithography

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

© Fraunhofer IWM

Numerical simulation of powder spreading in powder-bed systems

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

© Fraunhofer IGD

Cuttlefish - voxel-based, streaming-enabled 3D printer driver

Cuttlefish locally controls the process parameters (e.g. the laser power in the SLM process) and the material positioning (e.g. the material distribution in high-resolution multi-material 3D printing).

Make additive methods calculable, control additive methods

Additive manufacturing is closely linked to the digital control of the manufacturing process: Components are manufactured directly on the basis of a digital representation. The Fraunhofer Competence Field Additive Manufacturing develops algorithms to control additive manufacturing processes, for example to specifically design the optical properties of components, or to simulate individual process steps, e.g. to derive measures to reduce residual stresses and distortion.

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Algorithmics & Software

Software tools and the algorithms they contain are an essential part of additive process optimization and the digital process chain. This includes dither methods for material positioning in multi-material 3D printing with minimal material agglomeration or geometry-adaptive laser guidance in laser beam melting, where the rapid calculation of various geometric features (distance to component surface, orientation of offset surfaces, etc.) is necessary. Methods for "making printable" 3D models with faulty geometry (e.g. incorrect surface orientation, holes, non-manifold edges and corners) are also essential for an automated process chain and fall into this category.

Models and simulations

Simulation tools contribute to material development and to the optimization of process steps, e.g. to minimize distortions. The numerical approaches range from atomistic and thermodynamic simulations for alloy development to the flow, compacting and sintering behavior of powders, melt bath and microstructure development simulations of metals, mechanical models for the hardening behavior of resins, simulations of hybrid processes and post-treatment steps to the lifetime evaluation of additively manufactured components.

RISTRA - Rapid interactive structural analysis

In the virtual product development process it is often crucial to simulate the properties of many product variants in order to generate resilient decision criteria for the selection of the final design prior to prototype construction or series production. This classical product simulation is frequently used in generative manufacturing, but also in other manufacturing processes. In order to significantly increase the number of variants to be investigated, we have developed RISTRA - Rapid Interactive Structural Analysis. RISTRA is a graphics processing unit (GPU) optimized simulation software for structural mechanics that uses thousands of GPU processors to quickly predict three-dimensional mechanical stress distribution under given loads. Through efficient GPU data structures and massively parallel algorithms, accelerations of up to 80x compared to commercial software are achieved.

Simulation

Computer simulation and the technologies of Rapid Prototyping/ Rapid Tooling (RP/RT) have great potential for cost and time savings in industrial product development and are therefore becoming increasingly important. Even before a product, for example a newly developed machine component, is actually manufactured, the entire development process can be optimized quickly and cost-effectively. In a further step the RP/RT can also be used to produce first prototypes, small series or tool inserts for various manufacturing processes. In addition to the simulation, a complete real component verification and optimization is also possible.

Topology optimization - design of components according to load

Additive processes offer a simple way to produce so-called topology-optimized structures. Topology optimization here means the design, simulation and production of graded cellular structures for mechanically loaded components with high stiffness and low weight. Material is only built up where it is needed under load. Among other things, the processes are based on optimized distributions of different material properties in the component.

Component simulation

In the product development process, the Fraunhofer Competence Field Additive Manufacturing relies on virtual simulation techniques that cover the entire range from statics to dynamics. In addition, we develop tools with which transient, highly nonlinear calculations, such as drop test, load and failure analyses, can also be performed. Within the CAD-based simulation platform, individual components and even large assemblies can thus be handled very easily and efficiently. Special modules for calculation during the design process allow even sporadic users to check their designs and ideas directly at the CAD workstation.

Current developments

Complex internal structures

This is where additive manufacturing processes and systems can score particularly well: with their almost complete freedom with regard to the producible geometry - especially inside a component. Thus, for example, internal geometries can be produced that serve to save weight while maintaining mechanical strength. It is also conceivable to reproduce the human bone structure or to create reservoirs in implants for long-term medication. These processes are also suitable for the production of components with near-contour cooling channels, for example in injection molding tools, but honeycomb-like structures for flow guidance can also be produced. Internal, repeating geometries to increase the internal surface area can be produced with this process, for example to improve energy or mass transfer in heat recovery or filtration equipment.

Simulation for lightweight structures

A load- and weight-optimized design of complexly structured lightweight components is often only achieved by using suitable simulation tools. This allows the influence of various initial and operating parameters on component behavior to be investigated and optimized at an early stage. Modeling and simulation verifies design and production-suitable solutions already during the development phase and prevents planning errors that cause high follow-up costs and time delays. Special modeling and simulation tools allow us to efficiently describe mathematical calculation and model functions, provide access to static, dynamic or real measurement data and display the model results graphically.

Our services

Simulation of the construction - Virtual commissioning of machines and plants

The virtual commissioning of a machine or a completely automated system offers the advantage of testing and optimizing the control software already during the design and development phase. The basis for this is a real-time simulation that mimics the behavior of the entire machine design or individual components. The Fraunhofer Competence Field Additive Manufacturing offers concepts, tools and methods for the development of such system models on this basis, which offer you a number of advantages

- Short development times through software development on the machine/system model

- Quality assurance of the control software

- Further use of functional models.

Testing and validation

In many industries today, standard products from various CAD modular systems are used. However, the last components that have the actual contact with the product are manufactured at great expense and effort, either individually for each product or in single pieces or very small series.

The use of additive manufacturing processes not only improves the quality of partial functionalities selectively, but also allows the direct production of entire functional assemblies that are ready for use without further assembly steps.

Current developments

Simulation of production steps in powder technology

Based on innovative material models, the individual process steps in the manufacturing of powder technological components can be simulated numerically. Based on the results, the process steps can be optimized. This shortens the development times for parts with precise shapes, free of cracks, and reduces production costs. The spectrum of materials investigated includes powder metallurgical materials such as sintered steel and hard metal as well as technical and utility ceramics.

Simulations of process parameters of the SLM

In selective laser, melting, high spatial and temporal temperature gradients lead to residual stresses and distortion. By means of the incremental borehole method, a depth profile of the residual stresses for different temperatures of the component and different scanning strategies could be determined. The generative manufacturing at a higher component temperature strongly contributes to reduce the residual stresses. An optimized scanning strategy reduces the residual stresses even further.

Simulation of the stereolithography process

The interplay of increasing stiffness, decreasing flow ability and volumetric changes due to polymerization shrinkage and thermal expansion of the stereo lithography resin during curing leads to internal stresses and distortion. Simulations close to the process can predict these and contribute to the optimization of the process steps. A material model has been developed for light-curing resins that describes the course of the elastic, viscous and viscoelastic components of the deformation response during curing. The material model can be parameterized by suitable experiments. Simulation results on distortion show a good agreement with experimental results.

 

Our services

Design and simulation of complex structured components

With Selective Laser Melting as a rapid prototyping and rapid manufacturing process, metallic and ceramic components and tools are produced.

The work of the Fraunhofer Competence Field Additive Manufacturing includes process engineering, physical and materials science fundamentals, modeling to support and optimize process development, and the development of components for beam guidance and shaping, powder supply, and process monitoring and control. We also develop and install complete pilot plants.

Development of material models and simulation tools for additive processes

In many industries today, standard products from CAD modular systems are used. However, the last components that have the actual contact with the product are manufactured to a great expense and effort, either individually for each product or in single pieces or very small series.

With additive manufacturing processes, the institutes improve not only the quality of partial functionalities selectively; they also directly manufacture entire functional assemblies that are ready for use without any assembly steps.