Abstract:Sandwich composites are extensively employed in a variety of applications because their bending stiffness affords a greater advantage than composite materials. However, the aspect limiting the application of the sandwich material is its poor impact resistance. Therefore, understanding the impact properties of the sandwich structure will determine the ways in which it can be used under the conditions of impact loading. Sandwich panels with different combinations of carbon/Kevlar woven monolithic face sheets, in… Show more
“…It is worth-mentioning that the test specimens underwent drop weight experiment and they were clamped with the four edges to avoid the vibration of the target plate.Figure 4.Schematic of fractovis plus 7526 drop weight impact tester instruments. 36 …”
Nanoparticles are considered as feasible strengthening agent which strengthen different types of polymeric materials with minor reduction in the density of composites. In this study, 0.1 and 0.5 wt. % Graphene Nano Platelets (GNPs) are added to the matrix of basalt fiber reinforced epoxy composites (BECs) and the effects of such addition on low velocity impact behavior are investigated. In this regard, the epoxy matrix is reinforced in macro scale by basalt fibers weaved together in 2/2 Twill pattern. Vacuum Assisted Resin Infusion Molding (VARIM) method is used to fabricate the pure and multi-scale BECs. The profile energy method is also used to evaluate the penetration and perforation threshold of fabricated pure and multi-scale BEC specimens. The force versus time and deflection, energy and deflection versus time curves are plotted and the key parameters of low velocity impact test including maximum force, energy and deflection are compared. According to the results, introducing of GNP nanoparticles in the matrix of BECs improves the low velocity impact behavior of these composites by increasing the contact force and decreasing the absorbed energy in rebounding state. Finally, based on the experiments, the 0.5 wt.% BEC has the best impact performance by applying 15.08 kN impact force against the applied forces of 13.78 kN and 11.208 kN for 0.1 wt.% and pure BECs.
“…It is worth-mentioning that the test specimens underwent drop weight experiment and they were clamped with the four edges to avoid the vibration of the target plate.Figure 4.Schematic of fractovis plus 7526 drop weight impact tester instruments. 36 …”
Nanoparticles are considered as feasible strengthening agent which strengthen different types of polymeric materials with minor reduction in the density of composites. In this study, 0.1 and 0.5 wt. % Graphene Nano Platelets (GNPs) are added to the matrix of basalt fiber reinforced epoxy composites (BECs) and the effects of such addition on low velocity impact behavior are investigated. In this regard, the epoxy matrix is reinforced in macro scale by basalt fibers weaved together in 2/2 Twill pattern. Vacuum Assisted Resin Infusion Molding (VARIM) method is used to fabricate the pure and multi-scale BECs. The profile energy method is also used to evaluate the penetration and perforation threshold of fabricated pure and multi-scale BEC specimens. The force versus time and deflection, energy and deflection versus time curves are plotted and the key parameters of low velocity impact test including maximum force, energy and deflection are compared. According to the results, introducing of GNP nanoparticles in the matrix of BECs improves the low velocity impact behavior of these composites by increasing the contact force and decreasing the absorbed energy in rebounding state. Finally, based on the experiments, the 0.5 wt.% BEC has the best impact performance by applying 15.08 kN impact force against the applied forces of 13.78 kN and 11.208 kN for 0.1 wt.% and pure BECs.
“…20 Zhu and Sun 21 divided the low-speed impact response process of a sandwich layer structure into five stages and then established a prediction model for the contact force, impact displacement, and energy absorption properties. Samlal and Santhanakrishnan 22 assessed the impact behavior and the main failure modes of sandwich plates experimentally. Mohammadkhani et al 23 studied the effects of steel wire on the energy absorption performances of sandwich structures from both experimental and numerical perspectives.…”
The impact responses of various protective structures composed of 2A12 aluminum alloy and wood laminates were studied experimentally. The experiments were conducted using different impact energies. By varying the sandwich material thickness and using two different bullet shapes, the effects of the sandwich material’s damage process and the core layer thickness on the protective performance were studied. The multilayer structure’s core layer failure condition was determined using the improved 3D Hashin criterion and a finite element model was established using Abaqus software. Tensile and three-point bending tests were conducted and the progressive damage model was verified statically. The model was then verified dynamically using the Hopkinson bar test. The mechanical properties of the materials under high dynamic strain rates were obtained through action loading testing of the specimens at different loading rates. The loading waveform was analyzed and a stress-strain relationship diagram was drawn at various strain rates. By verifying the experimental data, a numerical model that could capture the deformation and failure details during crushing was established, and the composite target plate impact failure mode and the trajectory change law were described. This study could lead to use of a new impact damage prediction method for laminates.
“…The results showed that the impact resistance of the material can be improved by changing the panel material, panel thickness, and foam core size. Sun Ziheng and J. Zhou [13][14][15][16][17][18][19][20][21] studied the impact damage of composite sandwich structures from different stacking methods, different impact methods and different fiber layers, trying to find a structure with high impact resistance. Luo Zhiqiang et al [22][23][24][25] through the study of stitched foam sandwich structure technology, effectively improved the impact resistance of the structure.…”
In the process of use and manufacture, carbon fiber foam sandwich structures were often damaged by low-energy impact, resulting in performance degradation. Therefore, it was necessary to study the damage caused by low-speed impact of composite sandwich structures. In this paper, based on Hashin failure criterion, an equivalent finite element model of carbon fiber foam sandwich panel under low velocity impact was established. The model was used to simulate the damage of foam sandwich panel with [±45°/±45°/ (core) /±45°/±45°] ply structure under the impact energy of 10.58J, 21.17J, 31.75J and 42.34J. The simulation results of impact damage depth were compared with the experimental results. The error was less than 10%, which proved the rationality of the impact equivalent model. The model was used to predict and analyze the damage of foam sandwich panels with [±45°/ (core) /±45°], [±45°/ (0°, 90°) / (core) /±45°] and [±45°/ (0°, 90°) (core) / (0°, 90°) /±45°] ply structures under 21.17J impact energy. By comparing and analyzing the damage situation, impact force response time and impact velocity response time, the low energy impact resistance was analyzed. The results showed that increasing the number of ply structure of [±45°] can reduce the impact damage degree and improve the bearing capacity of sandwich panels.
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