“Generative design” is an umbrella term used to describe a variety of new CAD tools which are all engineered to optimize manufacturability, lightweight products and save on material usage. The end results can often be organic, alien-looking Giger-esque parts that save energy from machining operations. This results in cost savings to the manufacturer and efficient and robust parts, which can, in turn, pass savings on to the customer.
One company, in particular, is making strides in developing these methods. Autodesk already has topology optimization products available for public consumption and has some fairly mind-blowing new products in the pipeline (download their infographic What is Generative Design). So, settle down in your soon-to-be-obsolete chair, kick off your generic sneakers and let’s delve into the word of generative design.
Topology Optimization
Topology optimization is the first branch of generative design we will look at. Topology optimization has become a bit of a buzzword lately, due to the rise of additive manufacturing (AM) which has allowed greater geometric complexity in manufactured parts than ever before. But topology optimization has been around for over 20 years, and, like most technical fields, it has been lurking in the research labs of universities and high-end manufacturing companies.
The prominence of 3D printing has bought this subject to the public’s consciousness and we are now seeing more commercial-level software companies offering topology optimization for general consumption. One such package on the market is Autodesk’s Fusion 360.
Most (if not all) topology optimization solvers utilize 3D models and finite element analysis for determining load paths based on specified geometries, supports, boundary conditions and volumes (the design space).
Typically, a non-optimized 3D model is loaded into the software of choice, and the design space is defined in terms of the loads acting on the model, the materials used, the volume and general shape. Then, the FEA simulation (such as Autodesk Nastran) is run and the load paths are identified. The software removes superfluous material from non-load bearing areas and, there you have it, you have a lightweight part that is optimized for your design space requirements.
Anyone wishing to have a crack at topology optimization can do so by downloading Autodesk Fusion 360. Students can get a copy for free.
Lattice and Surface Optimization
Generative design principles that are becoming increasingly important, lattice and surface optimization applies internal lattices and optimized surface structures to an existing component to make it lighter and stronger. Similar in principle to topology optimization in the sense that it combines Nastran FEA solver with an iterative 3D design process, this method allows the user to lightweight parts not only by removing material as is the case with topology optimization, but fills load-bearing spaces and voids with variable density meshes. This allows the designer to fine tune the product in terms of weight, load requirements, flexibility and lattice topology.
These functions were first bought to the public by Autodesk in 2015 when the company purchased design optimization software called “Within” and added it to its own stable of CAD products. Perhaps you recall a pair of sneakers that were designed for sportswear manufacturer Under Armor a while back? Those were designed using the Autodesk Within package. Draw your attention to the funky looking lattice souls on those shoes for an idea of what lattice optimization and SLS 3D printing can achieve.
Trabecular Structures
A trabecula, according to Wikipedia, is a small, often microscopic, tissue element in the form of a small beam, strut or rod, that generally has a mechanical function. Our body is composed on many of these structures. The use of this structure in generative design precisely scales and distributes tiny pores throughout solid materials, and creates surface roughness to mimic bone in medical implants to help patients heal (as well as offer lower weight than traditionally machined implants). This method of generative design has been adopted primarily by the medical sector and has been used in combination with 3D printing to create a number of different implants for patients.
Human bodies tend to suffer when fitted with off-the-shelf components (because we are all different), and the design freedom allowed by generated trabecular structures have allowed truly bespoke parts to be implanted within patients. This has permitted increases in comfort to the user, as well as increased healing time, and a lower cost.
The way that the load carrying members are generated are similar in principle to those generated in the lattice and surface optimization methods. Due to the effectiveness of this method, the standard Autodesk Within package has evolved into Autodesk Within Medical, allowing not only variation in tiny lattices, but variation in porosity and surface smoothness too.
Form Synthesis
Whereas topology optimization can be considered a bottom-up approach to design—in which the end-product design space is defined and the product is decomposed and refined based on these definitions—Form Synthesis is a method that allows designers to input more general constraints and the software “grows” a new design. It also offers a number of other alternative designs for the user’s consideration. The Form Synthesis method follows nature’s design cues to allow organic and natural designs which may be beyond the imagination of the engineer. Form synthesis is truly a goal-oriented, top-down approach.
One such example of Form Synthesis software is Project Dreamcatcher from Autodesk. Dreamcatcher has been incubating within Autodesk labs for a couple of years, as the technology has been refined and tested both internally and by a number of industry partners such as Airbus and Under Armor.
Dreamcatcher was a Form Synthesis platform that utilized HPC and cloud computing and, now, the technology is being ported to commercial software having evolved into a service dubbed “Autodesk Generative Design”. Just last week Autodesk announced that this technology would be making its first commercially-available appearance in the Netfabb 2018 Ultimate package, Autodesk’s additive manufacturing platform.
“Autodesk Generative Design is not just topology or lattice optimization alone, it’s a massive step beyond that” said Greg Fallon, vice president of Simulation at Autodesk. “While optimization focuses on refining a known solution without any notion of manufacturability, generative design helps the engineer explore a whole cadre of functional and manufacturing design options. With Autodesk Generative Design, a designer or engineer can not only discover a new solution, they can then bring it to life using additive manufacturing tools.”
With these new design tools at our fingertips, we can expect not only efficiently produced and robust end-products, but I think it’s fair to say that the face of design may change forever.
No longer will design engineers be confined and bound by their traditional teachings, but they will be given a whole new way of looking at things, thanks to AI, machine learning and the computational power of HPC and cloud computing. With generative design in mind, the future is looking very interesting, both in terms of efficiency and aesthetics.
Autodesk has sponsored ENGINEERING.com to write this article. It has provided no editorial input. All opinions are mine, except where quoted or stated otherwise. —Phillip Keane