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youarenotyourstuff t1_j8motvt wrote

Reply to comment by dCLCp in NASA's "evolved structures" radically reduce weight – and waiting by Maxcactus

I agree that downsides should be discussed along with benefits.

I disagree that we don’t know how they work. Part of the process of generating these designs is defining the interfaces to other parts, the loads and the pass/fail criteria. You literally have to define how it works to the algorithm to get the design in the first place.

If you get those things wrong, even classically designed parts can fail. Garbage in yields garbage out.

This is also the reason for validation. Validation often finds unanticipated or misunderstood interactions and manufacturing defects. Which is why it’s needed regardless of design method.

And if a part fails, then you know something in the process (design or manufacturing) is flawed and you chase down the root cause, find an effective solution and correct the process that produced the issue.

Basically, it’s all standard engineering practices for bespoke designs. It’s not easy, but it’s nothing new.

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dCLCp t1_j8mr1nk wrote

What do you think are the downsides?

Someone else mentioned standards. It's impossible to standardize anything when everything is bespoke. What else?

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youarenotyourstuff t1_j8mtm65 wrote

A big one is that designing with this process means at every step you are highly dependent on complex software modeling. Instead of using well known design rules to develop your design, you have to run a sophisticated algorithm that probably needs a hefty amount of compute power. Then you have to run FEA on literally every part, again needing lots of resources. That kind of software isn’t cheap and neither are the computer clusters.

Also, you have to put a lot of effort into defining your requirements very precisely and uncovering hidden requirements. For example, if you need a lot of strength in a part do you need that in both directions or only one? If you only need strength in one direction the best solution might be a steel cable, but I don’t know if there algorithms would consider that.

There’s also part integration. Things have to be designed for manufacturing and service (part tolerance stack up, order of operations, tool and hand clearances, etc.)

You also have to carefully consider your validation and what assumptions it makes about the parts that might no longer be true.

In the end, generative design is probably only worth the effort for specific parts or even portions of those parts, not the whole product.

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____Theo____ t1_j8ny30p wrote

But all of these considerations are also in play when you design something without the gen algo. This is just engineering lol

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youarenotyourstuff t1_j8o99hm wrote

Yeah that’s my point. All the normal engineering steps apply for sure. Just some of them are made more difficult due to a complex shape instead of a beam.

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Khaylain t1_j8n3fig wrote

There's also a problem with adding on stuff later. For example you have some brackets to hold something, one made classically with mostly square shapes, the other with this type.

Then you later need to add some way to attach another thing to the bracket. With the classic version there might be the option to just add some threaded holes and it's done, with the AI/topographical version you'll probably have to start "from scratch".

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