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Armstrong

Generative Design and Stress Simulation

Yesterday I produced a second generatively designed spool holder design, but with an additional force imposed on the end of the cylinder to emulate it snagging on an obstacle, or being orientated in a 90 degree position, with the cylinder pointing upwards.

The images above show a comparison between the two steel spool holders. The original is shown on the left, whilst the new iteration, updated with the extra force imposed on the end face of the cylinder, is shown on the right. The first two images above appear to show the original model to have a greater amount of support and apparent structural integrity, but the plan view shows that the lower branch that attaches to the constrained block, has in fact been shifted backwards, providing more support in the Y axis.

I promoted/exported the latest study outcome to an independent model, which I then brought into the simulation space to begin exploring static stress analysis. Fusion 360 made this fairly straightforward since the option to recycle the settings from the generative design study was given.

One can see that the generative design has clearly worked to reduce material, whilst maintaining structural integrity (evident by the mostly even colour), but we are still able to see evidence of stress at the connection points between the branches and the existing geometry. However, to tell the truth, I was hoping for a lot more colour variation, to provide a more interesting powder-jet printed physical representation of the analysis. Whilst an expanded portion of the part could be used to better show the variation in colour, I decided to play around with the different visibility settings to show different results produced by the study.

Rather than highlighting stress, the above image shows the displacement of the part in mm. This produces a far more interesting visual, and the measurement is possibly easier to understand by those less familiar with the way that engineered parts are mechanically challenged. Whilst this particular image depicts a simulation showing the effects of a 1kg of weight placed on the top of the cylinder, the study that includes the additional force imposed on the end of the cylinder produced similar visible results. To communicate the results more explicitly, labels could be produced and placed on the final model to denote the exact estimated measurements.

One issue that I will need to consider during the design process is that the program assumes that the part is solid steel, rather than an object that has been additively manufactured. Whilst an AM setting is available within the program, it doesn’t contain configurable layer height, print bed orientation, or infill density. This means that these outcomes are optimistic compared to what may be produced in reality on the Markforged Metal X at PrintCity. Luckily, I have been told that the University has a materials testing laboratory, meaning that there may be opportunity test 3d printed parts and adjust the physical material settings accordingly, allowing Fusion to produce generative designs that align better with the manufacturing process. I am hoping that I will be able to get an induction to the facility after the holiday so that I can produce a better design.

In the meantime I will continue to develop the concept and begin to focus more on the assembly of the spool holder to enable it to be attached to the printer and to allow the mounted reel of filament to rotate and unravel smoothly.

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