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The use of additive manufacturing for the fabrication of sacrificial cladding is becoming increasingly popular as it facilitates the production of complex yet space-saving protective structures. Despite this, the effect of several structural parameters on their capacity to mitigate high-velocity impacts remains elusive. Toward this end, the shock-mitigating capacity of various short fiber-reinforced polymer samples was evaluated regarding impact velocity and mass (raging from 1 to 8.3 m/s and 5.5 to 7.5 Kg, respectively). Among the assessed parameters were peak force (measured to vary by up to 46.6%), max. and mean deceleration values (with max. differences documented at 29.5% and 48.2%, respectively) and cushion factor. As expected, the progressive crushing modes differed significantly across the spectrum of the tested samples. Structural failure involved the growth of inter- and intra-laminar cracks, fiber-matrix de-bonding and de-lamination, which was dependent on equivalent pore volume fraction and compressive strength. Increasing infill density led in most cases to higher peak forces during impact, as did the deposition of more solid peripheral layers, with the latter producing a superior deceleration plateau. Evaluated collectively, the results indicate that an infill density of 37% with 4 solid external (protective) layers exhibited the superior impact response among the tested samples.

The presented research work demonstrates an efficient methodology based on a micromechanical framework for the prediction of the effective elastic properties of strongly bonded long-fiber-reinforced materials (CFRP) used for the construction of tubular structures. Although numerous analytical and numerical micromechanical models have been developed to predict the mechanical response of CFRPs, either they cannot accurately predict complex mechanical responses due to limits on the input parameters or they are resource intensive. The generalized method of cells (GMC) is capable of assessing more detailed strain fields in the vicinity of fiber–matrix interfaces since it allows for a plethora of material and structural parameters to be defined while being computationally effective. The GMC homogenization approach is successfully combined with the covariance matrix adaptation evolution strategy (CMA–ES) to identify the effective elasticity tensor Cij of CFRP materials. The accuracy and efficiency of the proposed methodology are validated by comparing predicted effective properties with previously measured experimental data on CFRP cylindrical samples made of 3501-6 epoxy matrix reinforced with AS4 carbon fibers. The proposed and validated method can be successively used in both analyzing the mechanical responses of structures and designing new optimized composite materials.