TPU & PLA Combination Test

Evaluation:

Originally this model was designed to test the compatibility of two different materials and how they bond together when using an FDM printer. The printer printed these parts overlapping into each other to create a bond between the two materials but unfortunately unlike other successes from others online the two materials wouldn’t stick together, this created issues for all the other designs in the portfolio as they all work off this idea. To solve this issue contact pins were needed, all of which broke off due to the parts layer line orientations as further explained in each parts analysis.

Blade Protector:

Drone Parts - Blade Protector by Jayden Downes

Evaluation:

This part at first had issues due to the flaws of FDM’s structural integrity from the layer lines FDM printing uses. These caused the needed mounting pins (researched in the TPU & PLA sticking Model) to snap as they had to be placed in a vertical position when sliced in printing, although in a production environment this would be fixed through the use of Injection Moulding which uses metal molds carved accurately on CNC machines (meaning there would be no layer lines due to smoothing endmills being used for clean-up). In the production model, an epoxy in the form of Araldite was used to bond the two materials as the super glue was reluctant to stick to the Thermal Poly Urethane (TPU) parts and didn’t cure, this means the prototyping parts featured undesirable glue marks. Due to layer lines, the model also wasn’t strong with thin-walled parts and would snap, for this reason, parts had to be thickened but still worked perfectly in the end. After these issues were fixed the model was run in a Fusion 360 simulation engine and replicated with a drone crash to show how the parts would react during a collision and they provided extremely good results on the first simulation with around 1.8mm of displacement with a load of 3.4N replicating a crash of the 350g drone flying at 9ms-2. This simulation proved the part wouldn’t push into the drone’s body like the original part and lead to the blade being exposed during the collision.

Landing Gear

Drone Parts - Landing Gear by Jayden Downes

Evaluation:

For the landing gear, it was simulated that a from crashing from 100 meters high would create an impact of 343 joules and will crash at 44.27ms-1 or 159.38kmh-1, for this reason, the designs are made for a very low drop distance drop. The two designs included one set of landing gear for soft grounds and has vertical rods which are mainly used to land the drone flat and avoid the camera getting hit on non-flat soft grounds. The other design features Thermal Poly Urethane Stubbed feet that aim to absorb some of the energy by slowing down the reaction time much like an airbag, but these will not save the drone from breaking if it was to drop from a decent height of a few meters due to the crash speed. Even at 1 meter high, if the drone was to drop in mid-air like experienced by members of the year 11 engineering class of 2018 while testing, the drone would drop at 4.43ms-1 which has the potential to do serious damage to inertia and energy exerted on the parts of the drone as they absorb the energy exerted of going from 44.27ms-1 to 0ms-1 within the matter of a few microseconds. In summary, no matter the design it is almost impossible to save the drone from a few meters or more height if it was to fall out of the air especially considering the weight limits the drone is capable of lifting. Some students have chosen to do a cage format and this is seen to add to the overall weight of the drone and no matter how big the frame is and how much energy can be shared across the designed part, eventually all that force will be exerted on the drone due to the use of PLA Plastic and sacrificial parts will likely not help the drone either when falling from a height as it will create off-balance landing when the drone finally hits the ground and may cause damage to the camera or other components. For this reason, the two types of landing gear proposed focus more on lessening the impact when landing by being lightweight and using a rubber material to prolong impact times and lessen energy exerted on the drone, making a smoother landing, aiming to improve landing on uneven surfaces, harder or smoother terrains.