Do Airplanes Dream of Bionic Parts?

One of the best ways to innovate is by combining two different technologies. I am going to show you an example. This ultra-lightweight metallic part is the result of the combination of two state of the art technologies: additive manufacturing and topology optimization.

A350 XWB Bracket (© Airbus S.A.S 2014)

Topology optimization is a type of structural optimization which was discovered studying bones. Our bones are very lightweight because they have suffered an optimization through millions of years of evolution. On the one hand, holes have grown in low stressed areas. On the other hand, highly stressed areas have been reinforced. That is why our bones are lightweight and strong at the same time. There is bone only where it is needed. This has been studied and topology optimization software has been created. Now we can do the same as nature does in millions of years just in a couple of minutes. The result is a bionic design that is not only very lightweight but also very strong.

Topology optimization leads to designs that tend to be very complex and difficult to manufacture by conventional methods. Here is where additive manufacturing - also known as 3D printing - comes into play. Additive manufacturing is a technology that creates parts layer by layer. That means that almost any geometry can be manufactured by this method. In addition, there is practically no material waste and no tooling is required. However, it has to be said that surface roughness can be high, which reduces fatigue strength. And due to the manufacturing process, strength in the z-axis (perpendicular to the layers) will be lower than strength in the x- and y-axis (parallel to the layers). Therefore, it has to be taken into account that strength will be lower than expected.

In my opinion, the combination of these two great technologies has a lot of potential. It not only allows for weight reduction on aircraft and other vehicles, but also reduces material use, which can be very expensive for certain materials such as titanium. What do you think?

 

3D Printing Saves the Life of a Young Child

This component is 3D printed and it's made of a biopolymer:

It was developed by 2 professors from the University of Michigan.

Watch this amazing video in order to see how it saved the life of a young child:

3D Printing Makes You Fly Cheaper

General Electric is very interested in reducing weight in aircrafts, so they published a challenge in GrabCAD.com. The challenge consisted on reducing the weight of this component:

Image taken from www.grabcad.com

 

This component is a jet engine bracket. It's made of titanium (Ti-6Al-4V) and the new design will be manufactured using a 3D printer. Yes, you read it right! 3D printing nowadays is capable of printing metals.

The winner of the challenge will be rewarded $8,000.

The bracket will have to withstand the following loading cases:

Image taken from www.grabcad.com

The bracket is fixed with 4 bolts (interfaces 2 to 5) and the loads are applied by means of a pin (interface 1).

 

In my opinion, the best way to solve this problem is by doing a topology optimization. Why? Because a topology optimization will give you the lightest component that can withstand those loading cases.

I downloaded the bracket to be optimized and did a Finite Element Analysis. I wanted to know the stress level of the component before any weight reduction was carried out.

The maximum von Mises stress (of all loading cases) was around 530 MPa and was located at the pin hole. Considering a yield strength of 900 MPa for this titanium alloy and a Factor of Safety of 1.5, a maximum von Mises stress of 600 MPa shouldn't be surpassed. That means that there was still some room for material removal.

I used OptiStruct to perform the topology optimization. I took into account the 4 loading cases.

The objective of the optimization was to maximize the stiffness of the bracket and as constraint I chose a volume reduction of 60 %. The result was:

I exported the result to a CAD program and made the final design of the optimized bracket:

STL file imported to CAD

Final Design in CAD

After a Finite Element Analysis of the new bracket (for all the loading cases) I obtained a maximum von Mises stress of 585 MPa, which is under the limit of 600 MPa. The maximum was also located at the pin hole.

The results are AMAZING:

• 60 % weight reduction (from 2 kg to 800 g)
• Only 10 % increase in maximum von Mises stress (from 530 to 585 MPa). Stress under 600 MPa and therefore Factor of Safety over 1.5

In conclusion, topology optimization is a very powerful tool, which combined with 3D printing can lead to super-lightweight and super-strong components like the bracket of the challenge.

Lighter planes need less fuel. And fuel is very expensive. So this technology could really make your flight tickets cheaper! And you will fly as safe as always!

Furthermore, the benefits of producing less CO₂ and pollutants will benefit the whole planet!

So, will I win the challenge?

NOTE

You can see the whole GE Challenge here:

http://grabcad.com/challenges/ge-jet-engine-bracket-challenge