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[charlie T colton]

Project GenSim (subproject) / GenFLY (collaborative project)

More information on the GenFLY project that is the subject of the previous post, Ultralight and extremely stable (Das Fraunhofer-Magazin)


Projekt GenSim (Teilprojekt) / GenFLY (Verbundprojekt)

The link using Google Translate - Project GenSim (subproject) / GenFLY (collaborative project)

Occasionally the full web page Google Translate fails. Here are selected portions for those that can't view the translation.



Description:

In generative production processes, the inhomogeneous application of heat by the laser leads to undesirable effects, such as the occurrence of inherent stresses and deformations in the produced workpiece. Studies on this, in particular sensitivity analyzes, are still being carried out experimentally. However, these not only require an enormous amount of time, but also consume large amounts of expensive powder material and cause high energy costs by operating the plant. At the same time, an experimental determination of residual stresses and deformations is difficult. A more favorable and more effective alternative to the determination of residual stresses and deformations is the computer simulation. For this purpose, only a few approaches that depict the process using FEM simulations are usually limited to local, thermal calculations. The development of a multiscale simulation, which can make predictions about distortion and residual stresses even in more complex geometries, is necessary and makes it possible to perform sensitivity analyzes on a simulation basis. The further development of such simulation methods is an extremely important aspect for the advancement of the technology of generative manufacturing.


Current status:

In the project GenSim / GenFly, investigations are being carried out on the construction of thin plates in the additive production process Laser Beam Melting . When constructing such geometries, instabilities of the plates occur, which lead to unwanted results or even to process breaks.

For this purpose, the simulation method Mechanical Layer Equivalent, developed further in the previous project development, is used. Supported by numerous experiments of the Laser Zentrum Nord ( LZN ) , the residual stresses occurring during the process could be simulated at the ISEMP.

Remarkable are large areas in the interior of the plate, which are under partly high compressive stresses in the superstructure. This suggests that the unwanted instabilities are the known buckling effect (plate buckling ).

In the last project section, based on this knowledge, together with the LZN, strategies for the avoidance of the undesired effect or guidelines for a successful construction of the investigated geometries are developed.

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My takeaway from the Ultralight and extremely stable (Das Fraunhofer-Magazin) article is that the EBM process by it's very nature minimizes the need for additional process design constraints and limitations for internal component stresses that the laser based additive processes require.

From the magazine article referenced above:

Compared to the usual method of selective laser beam melting (SLM), electron beam melting is characterized by its high energy density and speed, resulting in higher building materials. Kirchner adds, "Furthermore, the process is carried out at high temperatures so that the components are virtually free of stresses." Moreover, the process runs in vacuo, which offers advantages for highly reactive materials such as titanium.

and

Experts are convinced that the currently still not widely used EBM process will find its place in additive manufacturing, as its strengths lie in high building applications and hard-to-use materials can be used.