Simpact Case Studies

High-flying technology for drone impacts

What is a UAV?

A UAV (Unmanned Aerial Vehicle), commonly known as drone, is a flying machine with no human pilot aboard. Commonly available UAVs for hobbyists and professionals are typically radio-controlled and can widely vary in shape, size and weight. 
For this project we teamed up with Aerialtronics, a leading Dutch UAV developer. Their signature product, the Altura Zenith, is a top-of-the-market professional drone that is ideal for our study. 

The Altura Zenith can fly for up to 40 minutes and carry an impressive payload up to 3 kg. 

Figure 1. Altura Zenith by Aerialtronics

Custom solutions to niche needs

Designing UAVs is a challenging activity.
 
FIGURE 2. SOME OF THE LOADS ACTING ON A UAV
A drone needs to be strong enough to carry a hefty payload and to survive a few harsh landings, but also as light as possible, to maximise payload and range.
This engineering challenge requires the use of the most modern materials and manufacturing techniques available in the Aerospace sector.

Advantages of FEA

FEA provides some unique advantages. FEA is accurate and can routinely predict the outcome of both static and dynamic experimental tests with near-perfect accuracy.

  • FEA is repeatable - You have a deterministic environment with complete control over the testing procedure. This enables the analyst to quickly identify and isolate the key design parameters.

  • FEA is safe - Experimental structural testing is a potentially dangerous activity. Certain tests involving people or other vehicles are simply too dangerous to be carried out in any other way.

  • FEA is inexpensive - By bringing the testing phase forward to the initial design stages, FEA limits the need for the production of expensive prototypes and the need for extensive test campaigns.

The numerical model

For this project we made use of Altair’s RADIOSS and OptiStruct solvers. The Altura Zenith was represented in a FE environment with over half a million elements. See Figure 5 below.

FIGURE 5. The Altura Zenith FEA model

The composite material constituting the majority of the structure was reconstructed – layer by layer – and correlated by means of experimental testing. See Figure 6 below.

Figure 6. Material ,model correlation
 

Experimental Testsing

The model was compared against destructive and non-destructive experimental tests, both making use of Simpact’s in-house drop-testing facilities. See Figure 7 below.

Figure 7. Non destructive hard landing test
 
The non-destructive test, a 30 cm free-fall, was designed to represent a hard landing.  A destructive test represented a 36 km/h crash and was carried out as a drop test from a height of 5.14 m. See Figure 8 below.
 
Figure 8. Full scale 5m drop test
 

Results

The model proved to be able to qualitatively and quantitatively predict the mechanical response of the UAV  to the various load cases, with an error of less than 0.5%  in the predicted static performance. Figures 9 and 4 below show the hard landing and 5m drop test overlay respectively.

Figure 9. ard Figure 4. Hard landing test and 5m drop test overlay

The numerical analyses enhanced our understanding of drone design and drone impact dynamics, allowing Simpact to generate a list of recommendations to further improve the crashworthiness of the product. Figures 10 and 11 illustrate the ehaviour of the model to a low speed crash landing and a high speed frontal impact.

Figure 10. and Figure 11. Low speed crash landing and high speed frontal impact.

The developed numerical model is now well suited to further investigate the effect of high-velocity drone strikes on both the structure of the UAV and the struck surface. An example of this being the leading edge of an aircraft such as that shown in Figure 12 below.

Figure 12. UAV model with aircraft wing leading edge

 

On completion of the project our Aerospace client said:

“Simpact’s extensive expertise helped Aerialtronics explore the effects of impact of a multi-rotor unmanned aerial vehicle (a.k.a. drone) with various objects. They were able to refine and validate existing structural models within a short time span. This allowed us to help fill a critical knowledge gap in commercial drone industry”


Jan Wouter Kruyt, VP Strategic Partnerships – Aerialtronics