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• Combining ML and FE methods to accelerate the design process of honeycomb structures. • Using 2D unit cell surrogate 3D honeycomb structures. • CDAE with a pixelation strategy is proposed to manage FE data. • LSTM uses latent features and external loads to predict structural dynamic responses. In this study, a novel framework was presented for accelerating the prediction of the mechanical response of honeycomb structures under dynamic crushing, using 2D cells to surrogate 3D honeycomb structures by machine learning (ML). The sizes of different honeycomb structures were designed and the necessary training data obtained through finite element (FE) simulations, but without using any explicit design parameters of the honeycomb cells in the ML model. A pixelization method of FE model was proposed to separate the complete cell structure from the honeycomb FE grid data and convert it into a matching pixel map. FE data was structuralized while reducing the large amount of computational power consumed in identifying complex array structures. Unsupervised automatic extraction of low-dimensional features of pixel maps was performed using a convolutional denoising autoencoder (CDAE). The crushing velocity and the extracted latent features were used as the input of the long-short term memory (LSTM) network to predict the crushing deformation and stress-strain curve of the honeycomb structure under different dynamic loading. Results showed that the constructed ML model could describe the dynamic crushing response behavior. Compared with the traditional FE method, the prediction model was 4.45 × 103 and 1.05 × 103 times faster in predicting the stress-strain and structural deformation response, respectively. The mechanical response prediction model provided a method for rapidly evaluating the dynamic mechanical response behavior of similar periodic array structures using FE model data, which could be beneficial for the design and development of equipment based on bionic structures. [ABSTRACT FROM AUTHOR]

• Relative density of honeycomb structures greatly influences their blast response. • The crushing velocity depends on mass, impulse and relative density of the core. • The sacrificial cladding solutions exhibit promising energy dissipation capabilities. The increasing use of improvised explosive devices in terrorist attacks against civil targets has challenged the scientific community to find new strengthening or protective solutions, able to mitigate the effects of the blast loads. As a response to this demand, the present study investigates the nonlinear response of 3D printed PLA honeycomb structures in order to analyse their energy absorption capacity when used as the crushable core of a sacrificial cladding solution. The dynamic response of the proposed sacrificial solution is experimentally obtained by means of an explosive driven shock tube, while the corresponding numerical simulations are performed using the commercial finite element software LS-DYNA. Both the experimental and numerical data are in good agreement and clearly show that, as expected, the dynamic force plateau and the specific energy absorption is directly proportional to the considered relative density, which controls the crushing of the top and bottom layers of the PLA honeycomb and the buckling of its interior cell walls. When compared with other available materials, the analysed sacrificial cladding solutions exhibit promising values of energy dissipation and encourage future research in this area. [ABSTRACT FROM AUTHOR]

Abstract: The in-plane impact behavior of honeycomb structures randomly filled with rigid inclusions was studied by using the finite element method to clarify the effect of inclusions on the deformation process, mean stress, densification strain, and absorbed energy. The deformation processes of the models were disturbed by inclusions; shear bands were pinned, and the cell regions surrounded by inclusions were shielded. Mean stress, densification strain, and absorbed energy per unit volume normalized by the values of the model without inclusions were found to be only dependent on the fraction of inclusions. As the volume fraction of inclusions increased, the normalized mean stress linearly increased and the normalized densification strain linearly decreased. The normalized absorbed energy per unit volume could be approximated by an inverted parabolic equation. The energy absorption of models with inclusions having volume fractions from 0 to 0.25 was larger than that of the models without inclusions. In particular, honeycomb models with fractions of inclusion from 0.1 to 0.2 exhibited the maximum absorbed energy. The model with a volume fraction larger than 0.4 could not be compressed because the inclusions in the model had already percolated before deformation. The in-plane impact behavior of honeycomb structures as energy absorbing materials can be designed by using the approximate equation and selecting the volume fraction of inclusions. [Copyright &y& Elsevier]