On The Propagation Of Fatigue Damage In An Aerospace Hybrid Shock Absorber Designed For Additive Manufacturing

Passenger safety is a major concern in the transportation industry, including aerospace. In this regard, the design of innovative systems for the energy absorption during impact phenomena plays a key role in the aerospace structures research field. This paper deals with the damage behaviour of an innovative shock absorber designed according to the Design for Additive Manufacturing (DfAM) rules. Indeed, the latter exhibits high mechanical properties while maintaining a low weight due to the combination of an innovative recyclable polypropylene core, produced by means of additive manufacturing technologies, with a carbon fibre reinforced composite material coating. In the frame of this paper, the innovative concept of additively manufactured shock absorber is integrated in the fuselage frame of a commercial aircraft as safety system for the passengers in the case of side impact. Specifically, numerical simulation of the interlaminar damage propagation of the shock absorber as a result of a side human impact is studied. The shock absorber, with a pre-existing impact delamination between the composite skin and the polypropylene structure, is subjected to cyclic operating loads to verify that the designed shock absorber falls within the damage-tolerant design scope, demonstrating to withstand the cyclic operational loads experienced by the aircraft still after an impact event.