The combination of topology optimization software and additive manufacturing can help you create a new generation of exciting products.

Tony Norton and Chad Zamler • solidThinking

3D printing and additive manufacturing (AM) have historically been used for rapid prototyping. This was, and still is a great application of the technology. Instead of making custom molds and tooling to manufacture prototypes, product development organizations can now simply create a CAD model and use AM to rapidly product a prototype. Not only does this save massive amounts of time, it also creates immense cost savings. In recent years the usage of additive manufacturing is now being used to manufacture production ready parts and products. Companies see the benefits of this manufacturing technique and are investing heavily. Organizations using additive manufacturing range from medical, to aerospace, and even consumer products.

Design for the freedom of additive manufacturing

So what is topology optimization, and how does it factor into the additive manufacturing process? Topology optimization is a mathematical method that generates a material layout within a given design space based on a set of loading conditions provided by a designer. Essentially, given the loads that a part or product will incur during usage, topology optimization software visually shows where non-vital material can be removed.

Using topology optimization, a designer can quickly and easily determine the most efficient usage of material early in the design’s concept development phase. With this new knowledge, a designer can create a final design that is strong, lightweight, and minimizes material usage. To demonstrate how the process works, let’s look at an example of a brake pedal optimized using topology optimization software solidThinking Inspire.
In this case, the initial design space was created in an outside CAD program. After importing the original design, loading conditions were applied. Within a few minutes, the software generated the optimized result.

Often, the result is an extremely organic shape similar to something one may find in nature. These organic results often require interpretation or the application of manufacturing constraints to be realized with traditional manufacturing techniques. However, additive manufacturing techniques are ideally suited to fully exploit this type of concept generation.

The first step in a topology optimization is to define the “design space” that represents the maximum volume that a part can occupy. This is the area that will be optimized. In this brake pedal example, the design space is represented in orange. Next, the loads that the part or structure will be subjected to are applied. In this example, the brake pedal is supported at the end, which can pivot. Forces are applied to the pedal itself at multiple angles where a foot may apply pressure.

In this simple case, the optimal result is an organic truss-like structure. This result can be exported as a solid geometry file to CAD for further interpretation, or directly saved and sent to be manufactured.

 

Real world usage

As the usage of topology optimization grows, its benefits for designing for additive manufacturing are becoming more apparent. Many companies are using topology optimization software to create unique concepts that are then produced using additive manufacturing.

The aerospace industry has been one of the early adopters of this synergy. Companies within this industry put a huge emphasis on weight reduction as a method to cut costs and increase efficiency.

Recently, the space division of Swedish aerospace company RUAG unveiled a new antenna support for an Earth observation satellite. The company relied upon topology optimization software to redesign the support structure with a load-sufficient material distribution. This new design was able to exploit the organic freedom enabled by additive manufacturing.
Once the design was completed, the final component was produced using an aluminum direct metal laser-sintering machine. The new antenna support design is half the weight of the previous model, with better rigidity. Measuring in at more than 40 cm long, the antenna, once it is launched, will be the longest known metal component produced with the powder bed manufacturing method in space.

Another company using topology optimization software to design for additive manufacturing is UK-based Renishaw. Renishaw worked with its partner Empire Cycles to design and manufacture the world’s first metal bike frame produced with additive manufacturing. Specifically, solidThinking Inspire was used to generate the ideal concept for the bike’s seat post. In this case, the organic seat post manufactured in hollow titanium is 44% lighter than the original seat post.

The automotive industry is also benefiting from using topology optimization to assist in the design for additive manufacturing. Mass reduction in this industry is critical to not only increase fuel economies and adhere to standards like CAFE, but also to increase payload capacity and decrease overall cost. HardMarque, out of Australia, sees the potential to use the cooperation between these two technologies to create on-demand, aftermarket automotive parts.

HardMarque’s most recent project used topology optimization to design a new lightweight piston head that was produced with titanium additive manufacturing. This aftermarket piston weighs 23.5% less than the original stock piston. “The lighter your internal components are, the lower your carbon footprint is. And not only that, because it’s additive manufacturing and not subtractive manufacturing, you are not wasting 90% of a block of metal to achieve the finished product. You are only consuming the material you need for the product,” said Nick Hard, director of HardMarque.

Efficient designs and products

One of the key benefits of additive manufacturing is that it has removed many of the traditional manufacturing constraints. As seen in the examples above, once these constraints are removed, the potential benefits of topology optimization are amplified. Saving product weight on a machined part does not necessarily save money. The size of the billet required is usually the same, but more material gets removed in the manufacturing process. With an additive technique, the amount of material used is directly proportional to the part weight: the heavier the part, the more expensive it is to make. Now a part designed using topology optimization to achieve minimum mass will save money in raw materials.

While the manufacturing controls in Inspire topology optimization software make it easier to produce models suitable for conventional manufacturing processes, those who use 3D printing have the freedom to produce more complex shapes. The unconstrained topology results are invariably lighter than an interpreted version and save more time in the development process.

Faster, smarter, lighter

This software is not just suited to parts created using additive manufacturing processes. Chris Heynen, senior design engineer, Race Face, a performance bycicle component manufacturer, has been using the software to help him and his team generate efficient structures for critical components. “When we first heard about Inspire, we assumed that our traditional 2D forging and machining process could not be optimized any further,” he said.

The use of Inspire allowed Heynen and his team to quickly study what effect changes to loading conditions or package space might have on their design direction. Said Heynen, “solidThinking Inspire showed us where we could remove all material not essential to the known end design,” he said. “Our final creation is a crank arm that is 25 to 50% stiffer at the same weight as the previous generation crank arm.”

Additive manufacturing and topology optimization share many common attributes, including the speed at which designs can be realized, the opportunity to quickly understand the effect of changes, and the delivery of the lightest weight solution. Companies are already recognizing the benefits of using the two technologies hand-in-hand, and there continues to be enormous opportunities to combine them to multiply their advantages.

solidThinking, an Altair Co.
solidthinking.com