Generative Design seems to be the new buzz-word and is touted to be the technology that is going to change the engineering world, but what is it and is it enough on its own?
In the past, designers have worked hard to optimise designs, reducing weight to make their products lighter and less costly to make. I can remember one of my customers going through this process over ten years ago. By making the parts lighter, the customer was able to reduce their manufacturing costs and their customers benefited by having a lighter product that could be used on smaller vehicles – a win-win for both! The process to achieve this involves an engineer using their knowledge and experience to work out how and where the weight of the parts can be cut away and then run it through a FEA study to determine what effect this has. The process is repeated until an optimal design has been reached, but is limited by the inspiration of the engineer, the modelling capabilities of the CAD software and the time and money you wish to spend on it.
The new generative design tools that are emerging are running the same process, but in a more automated way. The process starts in the same way you would set up a stress analysis study, by specifying the fixed points and the loads, along with specifying any regions of the model that need to be preserved. The next step is to specify what sort of improvement you are aiming for, whether it be a proportionate reduction in mass or a fixed amount and what are the allowable stress values you are happy to live with.
The analysis will work out the low stress points and remove material from where it is not needed, leaving a much lighter part. See the whole process in this video:
Obviously, the resultant model is far from what anyone would imagine or design (some of which would be hard to model) and would have only been able to be manufactured in the past by casting, which can be expensive, especially for short runs. Now, the technology behind 3D printing is growing at an amazing rate and is really becoming a viable option for production parts. One of the nice things about the Siemens implementation is that the resultant body has quite a smooth finish – see the following example.
One problem that many systems using this process have, is that the model created using the generative design process is a mesh model, similar to what you would get from reverse engineering – great for 3D printing, but how is this used in assemblies when your overall design is built with B-REP (boundary representation) models? What does this mean? Firstly, it means that there are no true “faces” in a mesh model, so you will be unable to build relationships between it and any normal part in an assembly. Secondly, there are no easy ways to make modifications to the model. The following diagram shows this graphically.
The next part is the critical bit and shows that Siemens look at the whole picture, not just isolated developments. With the introduction of generative design in ST10, Siemens also enhanced the reverse engineering features and added the ability to add features on to mesh data (named convergent modelling). Both of these techniques enhance the workflow, so that mesh models can become more integrated with B-Rep models in an assembly.
This video shows how a mesh model can be modified and B-REP surfaces added so that the mesh model can be used:
To round off the whole workflow, Siemens have also made it easier to 3D print models (mesh or B-REP), with new tools to position and select material when printing to your own 3D printers. A portal has also established for you look for providers of 3D printing services, which will quote a price and offer delivery schedules for printing your models.
So how do these tools fit in to the current software? Solid Edge Generative Design is available in both Solid Edge Classic and Premium, and allows you to set up and run full generative design studies. This allows for visualization of optimum light weighted/minimal material designs, primarily used as “inspiration”, requiring you to go through the manual process of designing a b-rep part around it. Generative Design Pro (which is an add-on to classic and premium) allows you to not only generate the optimum design, but also to release the mesh body from the study and make edits directly to the model. This includes adding or deleting features, using all reverse engineering tools, and generally having access to all convergent modeling techniques available in Solid Edge. As for the other tools, convergent modelling (mesh data reuse) and additive manufacturing are available in all 3D versions of Solid Edge.
So, in summary, Siemens are not only providing the next generation tools, but have the foresight to ensure they are not isolated functions, but truly integrated into a workflow that will ensure maximum benefits.
13,296 total views, 45 views today