ADDITIVE MANUFACTURINGSECTION TITLE
Fig. 2 shows the extremum principal
stresses and regions of stress concentration near the motor mount as well as on the top and bottom (not shown) of the drone. Te lowest factor of safety (FOS) for the original design is approximately 1.5, validating that the original design would satisfy load requirements made with the originally intended manufacturing process and FOS. Te initial FEA results informed the
design direction to reduce the stress concentrations in the X-shaped support region and integrate parts in the motor mount region of the original design (shown in Fig. 3). To improve the strength in this region, the X-shaped supports were replaced with a conical motor housing and were integrated with the boom and landing gear.
ADDITIVE FEA AND SLICING Once the software informed the design direction through the initial FEA, a final design was prepared. Te additive finite element analysis (AFEA) module in Xplorator was used to validate the design’s strength, taking into account the anisotropic properties of Arevo’s composite
FIG. 2. Extremum principal stress for the original drone design with 8kg payload
FIG. 3. Multiple parts in the motor mount region of original design and updated motor housing design
filament used as feedstock for the Aqua system. Te input for the AFEA module is material properties from extensive characterisation performed on coupons printed via DED on the Aqua system. Using the same 8kg payload load case, AFEA was conducted on the final design. Further analysis (see Fig. 4) revealed a high FOS of 5 in most regions with the lowest FOS of 2.63 near the top surface. Te high FOS suggests that the weight can be further reduced in select regions for future
prototypes, with an initial conservative estimate of 10% further weight savings – 60% below the original design. Upon structurally validating the design, the final toolpath and manufacturing blueprint, or GCODE, was prepared using the slicing module. Looking closely at a subsection of the sliced model, the continuous fibre path wraps from one side of the boom, around the motor housing and supports, and onto the other side of the boom to meet the rest of the chassis, therefore providing continuous fibre support around the perimeter of the chassis and booms of the final design. Once the manufacturing blueprint was
FIG. 4. Extremum principal stress of the final design to be manufactured via DED
prepared, the part was manufactured on the AquaSystem. High tolerance holes were later machined via CNC. In conclusion, 50% weight reduction of the original design was achieved and the structural requirements were met for the load case provided using Xplorator to inform and validate Arevo’s optimised design. Te next step is to perform assembly and flight testing to inform future design and product improvements. Te drone case study showcases how this technology enables both virtual design iteration for additive manufacturing of composite parts and virtual validation before manufacturing to achieve lighter weight structures. Additionally, there is an opportunity for further weight reduction in select regions where the FOS is high. Finally, Arevo believes that this design can be further optimised to integrate the parts into one printed, structural frame.
Magda Zydzik works in applications development at Arevo.
www.arevo.com
www.engineerlive.com 17
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