Structural Optimization and Experimental Validation of a Composite Engine Mount Designed for VTOL UAV

Unmanned air vehicles (UAVs) with vertical take-off and landing (VTOL) capabilities, equipped with rotors, have been gaining popularity in recent years for their numerous applications. Through joint efforts, engineers and researchers try to make these novel aircraft more maneuverable and reliable, but also lighter, more efficient and quieter. This paper presents the optimization of one of the vital aircraft parts, the composite engine mount, based on the genetic algorithm (GA) combined with the defined finite element (FE) parameterized model. The mount structure is assumed as a layered carbon composite whose lay-up sequence, defined by layer thicknesses and orientations, is being optimized with the goal of achieving its minimal mass with respect to different structural constraints (failure criteria or maximal strain). To achieve a sufficiently reliable structure, a worst-case scenario, representing a sudden impact, is assumed by introducing forces at one end, while the mount is structurally constrained at the places where it is connected to wings. The defined optimization methodology significantly facilitated and accelerated the mount design process, after which it was manufactured and experimentally tested. Static forces representing the two thrust forces generated by the propellers connected to electric engines (at 100% throttle and the asymmetric case where one engine is at approximately 40% throttle and the other at 100%) and loads from the tail surfaces were introduced by weights, while the strain was measured at six different locations. Satisfactory comparison between numerical and experimental results is achieved, while slight inconsistencies can be attributed to manufacturing errors and idealizations of the FE model.