Blast Resistance Simulation And Multi-objective Optimization Design Of Lightweight Aluminum Foam Sandwich Panels

It puts forward higher requirements for military vehicle armor protection with the change of global strategic situation and the development of anti-armor weapons. The new armor structures with good defensive performance and maneuverability as well as lightweight attract more and more attention in the field of military vehicles protection. Metal foam sandwich structure has a remarkable potential prospect because of its lightweight, high strength and specific stiffness characteristics, excellent energy absorption and buffering capability. In this work, the dynamic responses of three types of aluminum foam-cored sandwich panels under blast loading were investigated through nonlinear explicit finite element method. In addition, multi-objective optimization of the aluminum foam sandwich panels were performed.Firstly, the dynamic responses of six types of uniform aluminum foam sandwich panel (UAFSP) with various combinations of face-sheet materials under blast loading were analyzed by employing the LS-DYNA software. The effects of material properties on the blast-resistant performances of the UAFSPs were investigated. It is found that the panel with a soft front face and a relatively hard back face outperforms the other panel configurations in terms of blast-resistant indices. Based on this result, parameter studies were carried out by changing the front and back face-sheet thicknesses, core thickness, aluminum foam density, boundary conditions as well as standoff distance (SoD) between the panel and the explosive. Further, multi-objective design optimization (MDO) of the UAFSP to minimize MaxD (maximum back face deflection) and maximize ASEA (areal specific energy absorption) was performed both with and without variations in blast load intensity, which The design variables were material constants and dimensions of the panel. Artificial neural networks (ANNs) were used as approximation models. The optimization results show that the two objectives of MaxD minimization and ASEA maximization conflict with each other and that the optimal designs must be identified in a Pareto front. Moreover, the Pareto curves obtained are different for varied blast impulse levels.Secondly, the blast performance of curved aluminum foam sandwich panel (CAFSP) subjected to air blast loading was studied numerically. Deformation of the CAFSP was compared with that of the UAFSP. The research which focused on the influence of radius of curvature on the anti-blast properties of sandwich panels shows that panel curvature affects the deformation shape of CAFSP and has a monotonic effect on ASEA in the studied range. However, it shows a non-monotonic effect on the MaxD of the panel. Based on these findings, MDO of the CAFSP was carried out. It is found that the deformation modes of CAFSP are different for varied radius. The density of aluminum foam has a greater influence on the two evaluating indicators of anti-blast performance than others. Compared with the initial design, the blast resistant performance of the designs on the Pareto front is improved significantly.Thirdly, the concept of graded-density aluminum foam sandwich panel (GAFSP) was introduced and the blast resistance of GAFSP with various core layouts (sequence of foam layer density) was analyzed and compared. Using MaxD and ASEA as blast-resistant indices, the graded core is found to provide a significant design-ability of the sandwich panel against blast loading and the panel featuring alternating graded core layouts has the best blast resistance. It is also found that the GAFSP has a better blast-resistance than that with traditional uniform core of the same weight. According to previous studies, multi-objective optimization of GAFSP was performed with respect to the relative density of each layer of the graded core. The results show that blast resistance of the graded sandwich panel could be further enhanced through optimization.Finally, the aluminum foam sandwich panel was applied to the anti-mine design of a military vehicle. The dynamic responses of the vehicle and the dummy injuries were numerically analyzed for the baseline vehicle as well as the vehicle with aluminum foam sandwich panel armor. The simulation results show that the aluminum foam sandwich armor panels can effectively improve the anti-blast performance of a military vehicle and the safety of crew under blast loading.