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DROP TEST ANALYSIS for COMPOSITE LANDING GEAR of UAV

DROP TEST ANALYSIS for COMPOSITE LANDING GEAR of UAV

Introduction:

Landing gear is a very major component in any UAV. The landing gear provides a stable support for the aircraft at rest on the ground. During landing, it acts as shock absorbent mechanical structure to absorb and transmit these loads to the stronger part of the UAV (fuselage) so that a majority of impact energy is dissipated. Landing gears also act as brakes during the motion of the UAV on the runway.

DROP TEST ANALYSIS for COMPOSITE LANDING GEAR of UAV

Challenges:

Complex physics representation due to solid composite strut attached to rubber tyre with pre-tensioned bolts and tyre filled with 40psi air pressure using hydrostatic fluid elements. Complex contact conditions with geometric non-linearity between rubber tyre and concrete.

Assumptions:

  • Composite strut is made of GFRP sheet with 22mm thickness (88 plys, Each ply thickness
    is 0.25mm) which is FE modelled and composite strut damage mechanics was modelled using Hashins damage model .
  • Tyre is modelled with Hyper-elastic mooney -rivilin material model which is filled with air
    at 0.275Mpa (40psi) assuming Ideal gas molecular weight of 0.044Kg. Air is filled in the
    tyre using hydrostatic fluid elements
  • Four M6 Bolts between the tyre and strut are modelled with steel assuming strength class
    of 8.8 with a pre-tension of 9190N. Between Concrete floor (Mohr-Coulomb Plasticity
    material model) and the landing gear the coefficient of friction was assumed as 0.55.
    Implicit transient dynamic analysis procedure was used to solve this drop test and
    simulated for 2 sec.
  • Mass of 300Kg was taken and distributed on the bulkhead of the Landing Gear. The total
    weight of the landing gear was approximately 19Kg. Weight of the composite strut is
    6.62Kg

Engineering Solution:

Adaptive meshing technique was used to increase the accuracy of the problem and the Tsai-wu index was optimized below 0.6 by changing the ply angle orientations.

DROP TEST ANALYSIS for COMPOSITE LANDING GEAR of UAV

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