This diploma thesis addresses the development of an additively manufactured kinetic-energy
absorber for cushioning the impact of a 70 kg payload airdropped by parachute. The
objective of the work is to design a modular absorber composed of four corner units that, at
an impact velocity of approximately 5.4 m·s⁻¹, limits the peak transmitted acceleration of
the payload to below 15 g.
The absorber is formed by an internal lattice structure printed by fused filament fabrication
(FFF) from polyamide reinforced with short carbon fibres (PA12CF15). Four candidate
lattice topologies were first compared by quasi-static compression tests and dynamic
drop-tower tests using a unified test methodology; the chiral topology was selected for the
functional prototype owing to its stable plateau stress and favourable ratio of absorbed
energy to mass. The mechanical response of the printed material was characterised by tensile
tests at several strain rates covering both the quasi-static and the dynamic regime.
The geometry of the chiral cell was optimised through a parametric finite-element study in
the explicit solver LS-DYNA, employing a material model that reflects the rate-dependent
response of the polymer composite. The numerical model was validated by drop-tower
experiments on a representative set of configurations. A regression relation between relative
density and plateau stress was derived from the parametric study data and combined with
a design map, which together with an iterative procedure enabled analytical sizing of the
corner-unit functional prototype.
The functional prototype was manufactured by FFF and its response under simulated impact
was verified by an FE simulation. The thesis delivers a complete methodology for the design
and validation of a printed single-use absorber – from material and topology selection
through a parametric FE study and regression analysis to experimental verification and
iterative sizing of the functional prototype.