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Topology Optimisation for Additive Manufacturing

Hello,

I'm currently working on a university project which is investigating the use of topology optimisation for additive manufacturing (AM). One of the side effects of some AM processes is that built components will exhibit different mechanical properties along each axis. This is dependent upon orientation of the design within the AM build chamber.

In respect to Selective Laser Melting or Electron Beam Melting in Titanium-64, could anybody recommend an approach (within Optistruct) which could account for the varying mechanical properties? Alternatively, if anybody knows of a way to heat treat AM parts so that the anisotropy/orthotropy is negated during optimisation, that too would be helpful.

Any help with this issue would be hugely appreciated!

Thanks,

Dan Walton

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Rahul Rajan_21763

Hi,

Just sharing relevant information to your query.

http://www.altairatc.com/europe/eatc2013-abstracts/day1/session-3/eads-muir.html

http://altairatc.com/europe/eatc2013-abstracts/day1/session-3/eads.html

Regards

Rahul R

Altair Forum User

Hi,

Rahul, thanks for pointing me towards the additive manufacturing case studies for topology optimisation. However, the presentations do not specifically mention an approach to material anisotropy.

To build upon my previous post, I have found an academic paper which reports the mechanical properties of EBM and SLM Ti64. It was found that round tensile specimens exhibit a mean-average yield-strength only 3-5% greater in the horizontal orientation than in the vertical. On the other hand, I have found that the varying mechanical properties are much greater in processes such as fused deposition modelling. So my question is this - Since the mechanical properties of SLM/EBM do not significantly alter upon build direction, could the material be treated as isotropic during topology optimisation?

I'd be interested in knowing anybody's response to this.

Thanks,

Dan Walton

P.S. For those who may be interested, the academic paper was entitled 'Microstructures and Mechanical Properties of Ti6Al4V Parts Fabricated by Selective Laser Melting and Electron Beam Melting' by H.K. Rafi et. al.

Altair Forum User

Hi Dan,

Does the strain behave the same in all directions?

I think its completely your call whether to consider as an isotropic or not. Maybe you can consider as an isotropic and study the behavior. I think it makes a good study.

Altair Forum User

Hello,

I just came upon this topic. I have exactly the same problem.

Since I am trying to optimise for FDM, the material properties vary a lot in x, y and z direction.

I have tried Optistruct with PPCOMP and MAT8, but this did not work.

Any idea's?