New generative design practices

3D printing and generally additive manufacturing practices, have opened new opportunities for design engineers.

Traditionally, designing a part was done by adopting a conventional way of thinking. Function of the part would dictate its attachment points and degrees of freedom. Then from this stage on, the part would be drawn with relatively straight faces cut from blocks of material on a CNC machine, or with draft angles required for injection molding, RTM or casting.

The conventional way of thinking restrains the design in a relatively known concept and expected shapes result from this.

However, straight face, machinable/ moldable shapes are not required any more with 3D printing. Much more biological shapes can be created like bone lattices.

Using the technology found in the nature is possible by either copying what can be seen on plants in animal bodies. But more dramatically, ground up designs can be achieved by reproducing the evolution process described by Darwin at an accelerated pace. This is called generative design. The idea is to start from functional constraints and grow parts according to specific senarios, then test/ compare the converging designs. The most appropriate design/ the one fulfilling the design criteria the best will be chosen.

The parts created with this process end up being remarkably "biological' in their shape. The benefits are mostly on weight saving for a given load baring.

Here is an example below created with the Siemens generative design module.

The original part is a stabilizer rotation bracket. The part is very standard in the fact that it is created from a block of alloy and CNC machined on 5 axis.

 

After applying the principles of generative design and selecting from a number of iterated senarios, the retained product is as followed:

 

 

One can clearly see the bone lattice style in this design as well as some non trivial section changes at first glance. These non linear section changes are necessary to ensured the propagation of the efforts without strain accumulation.

One interesting point here is that we can see the traditional mechanical design still transpiring in the rotation axis. We still have cylindrical shapes.

The next step in engineering design evolution will certainly be in re-thinking the degrees of freedom and parts joints. Look at how our joints are made...

 

In any case, we have started adopting generative design on our Siemens NX stations on most of our products. This is already visible with our new GenTech 3D printed hatch latches and Cloudtech retracts.