Submission Topic: Please post your competition entry here!

Milad_Mafi · January 23, 2016, 3:42pm

Hey SimScalers,

Please use this forum topic only to submit your competition entry

To create your post click the Reply button below and be sure to include all of the following information:

Link to your public simulation project, including the geometry of your modified drone, the mesh as well as every simulation run that was used in your result interpretation

A brief summary of your work: Please describe your design modification, the simulation setup and how your modification improved the performance metrics (i.e. increasing the lift of the drone, reducing the weight of the frame, the structural integrity of the design, 3D printability)

Post-Processing images (plots as well as 3D images) which prove and explain how your design modification improves the performance. Please submit at least 5 different pictures.

** Please note that one you have posted your submission it will be public in our forum. **

Submission Deadline: March 15, 2016 at 11:59 CET

Cheers,

Milad

awadh_kapoor · February 26, 2016, 11:36am

DRONE CHALLENGE - Awadh Kapoor

Stage 1: Drone Arm Modification
Major Modifications: (Ref. to attached images for the drawing - figure 1)
1.Hollow Circular Cross Section of Arm for a uniform stress distribution and to avoid stress concentration.
2. Arm consist of many holes to reduce weight while maintaining strength. (Design Inspiration from Aircraft Fuselage, optimal to take bending loads.)
3. Arm joins to the motor base with a twist drill shaped feature, considering drone arms are subjected to torsion when in roll. The twist drill feature is considered the most reliable design to take torsional loads.

Simulation Setup: A simplified model of the drone arm was put under a lift load of 2.25 N while constraining it at the top and bottom face of the support. In a total of 6 simulations, 3 for each design considering the different materials available (Details in table 1), the results are detailed in table 2(Ref. to attached images). To keep the FEA comparable of the two designs, the resolution level has been kept same for both.

RESULTS ( Refer to figure 2 and figure 3)
1. WEIGHT: Considering the SimScale arm is made of ABS Plastic, for the modified design made in ABS, PERCENTAGE WEIGHT REDUCTION = 26%. Since the stresses is quite low in the modified arm, making it out of POLYAMIDE, we lead to PERCENTAGE WEIGHT REDUCTION=37.6%.
2. STRESS: The modified arm has no stress concentration points, it has a very uniform stress distribution, leading to a REDUCTION IN MAXIMUM STRESS by 65%
3. DISPLACEMENT: The modified arm has a MAX. DISPLACEMENT lowered by 10% as compared to the original design.
4. PRINTABILITY:The modified arm NO SHARP CORNERS, is SYMMETRIC and has a nearly constant circular cross section, making it a printer friendly choice.
5. DESIGN The holes and the hollow design make it fit for putting all the wires inside the arm unlike the original design. This not only preserves the aesthetics of the design but gives Protection to wires against any cuts.

Stage 2: Propeller Modification
Conditions To increase the lift from 2.2 N to any greater value. (Keeping the blade diameter same, since any increase will lead to an increase in the arm length to take care of tip clearance and aerodynamic interference, which will ultimately increase the weight of the arm.) Variables available are airfoil parameters and twist.
Major Modifications: 4 options were considered, designed/modified using an open source code called Java prop (http://www.mh-aerotools.de). Since it is based only on the blade element theory and misses the 3D effects calculation as well as the inputs from momentum disk theory, certain modifications were made to the propellers based on hand calculation and historical data of commercial propellers (Gemfan). The details of the design are as follows.
Design 1-A new design based on the propeller of the spitfire modified using Javaprop for current application.
Design 2-Design based on the given propeller modified using data from Gemfan and Javaprop
Design 3-Same as Design 2, with changed pitch and airfoil chord.
Design 4-Same as Design 2, with 3 blades.
Simulation Setup : To compare the 4 blades, only the propeller was analyses using MRF. Once a suitable choice was made, the propeller was assembled with the motor on the modified arm and analysed again to take into account the loss of lift due to interference from the arm.Design 3 and 4 provide much greater lift but since the efficiency of a propeller in inversely proportional to the number of blades, Design 3 was the best choice. Table 3 (Ref. to attached images) gives the details of the results.( Figure 4,5,6,7)

Here is the Project Link

Same details are organized in a pdf here.

Thankyou

ECChan · March 15, 2016, 10:12pm

In the following optimization study a design of propeller was setup in CAESES with fully parametric model the design was based on NACA 4 digit profile, and parameters such as chord length, camber, camber position, thickness pitch and rake was controlled by functions describing the distribution of those parameters along the span of the blade.

Multi section profiles of the design blade:

Sobol optimization algorithm was used to creat arbitrary design samples more details about the parametric design can be fond in the following link :

Drone Blade Design › CAESES

These design samples was analysed and showed the following results:

1 - for the first step in the optimization 50 different designs was evaluated by the lift force, the following pictures shows all the different designs and the base line and the best design candidate.

Clearly the improvement was remarkable from the first run in term of lift force from 2.13 N for the base line up to 5.46 N.

The following pictures shows the difference between the base line and the optimized design

the baseline design

best design

the baseline design

best design

2 - Second step in the optimization was to investigate the effect of the number of blades, in this stage 3 different configurations was investigated 2, 3 and 4 blades.

The following picture shows the effect of the number of blades on the lift generated by the propeller.

We can see clearly that the number of blades have a significant effect on the lift generated by the propeller, and from 5.4 N of lift from the best design using 2 blades up to 8.47 N with the same blade design but using 4 blades.

Here you can see the 3 different propellers with same blade profiles and different blade number.

For more details about the performance of this propeller design the following graph shows the performance of the blades compared with the base line.

3- For the last optimization run the radius of the propeller was varied to see the effect of the diameter on the lift generated by the propeller. at some point this parameter need to be bonded to keep the design feasible, for this test the propeller with 4 blades was used .

The graph shows that small variation in the diameter can create too much improvement in the lift and this is because the lift is affected by the square of the surface, and with 4 blades so for this reason we can see that the lift was doubled in the last test.

Of course to design propeller is not only important to investigate how much lift you can generate but also the drag force is really important factor and finding the most efficient design can be great challenge for the next stage in the optimization.

Note : For some technical problems the we was not able to shows some CFD post processing and the simulation links we will deliver it as soon as possible

rtegelbeckers · March 15, 2016, 11:16pm

Hi there,

I only found out about the competition yesterday and only started modelling today. I hoped to ‘steal’ someone else’s project as a template, replace the arm geometry with my own and press ‘go’… Given the time constraint I only managed this:

Create model in SolidWorks
3D print some arms in ABS (7 gram mass!) and PLA
created a static FEA:simulation

Rendering of quadcopter with the new design arms

Redering from a different angle. Notice the holes in the arms for accepting the motor wires.

Several 3D printed arms in ABS (top two) and PLA (bottom). The middle arm demonstrates how the hole in the arm can accept wires.

This ABS arm shows a mass of 7 grams on the weighing scale. The latest version of the arm in ABS (as simulated) would be 6.8 grams according to the CAD software.

Initial displacement plot

Initial von Mises stress plot, showing an fairly even stress distribution.

Set of final design arms printed, ready to be used on a lucky drone!

I tried to achieve a light and small arm construction by creating a hollow tube, allowing cables to be threaded through. Also, by bending it out of the way of the prop I tried to improve the air flow around the propeller. This also made it perform the function of landing leg. Should be good in strength, fairly stiff, very light, easy to print, and aerodynamic in vertical and horizontal direction. A shame I did not have enough time to verify for the competition. I am sure it would have performed very well.
Cheers,
Richard

PS. It would have been nice to provide info in the competition for the restrictions in regards of the amount of images that can be uploaded by new users, especially as several images are required by the same competition - missed the deadline because of it…

Update 16-03-'16: @AnnaFless changed the permissions on my account, so I can add more than one image. Many thanks!!! I removed the initial, single image and replaced it with individual images.

mouffouk_m_a · March 16, 2016, 7:29am