Rock shed is widely used in traffic lines against rockfall. In order to cushion rockfall impact and dissipate impact energy, cushion layer is usually adopted in rock shed. Used tire cushion layer is proposed in this paper and it can cushion rockfall impact utilizing large radial deformation of tire. Reinforced concrete structure model is built with used tire cushion layer and artificial rockfall test is carried out. Twelve tests are divided into 4 sets with different rockfall mass, rockfall height, and tire filling material. Simplified calculation model with spring-damper is derived from radial repeated compression test of used tire, which improves the calculation efficiency. Test and numerical simulation show that application of used tire cushion layer in rock shed can cushion rockfall impact and effectively reduce peak acceleration and the maximum impact force. Filling sand and gravel in tire can improve tire stiffness and energy absorption capacity but will decrease cushion effect due to its large density. With the same impact energy, light rockfall is more destructive than weight rockfall for used tire cushion layer.
This paper proposes a sand-filled aluminium honeycomb sandwich structure for protective structures. Based on the results of the theoretical analysis, the author conducted a drop weight impact experiment was conducted on several specimens, seeking to obtain the data on impact load, impactor displacement and structure deflection, and observe damage modes of structures at different impact energies. Then, the LS-DYNA was employed to validate the simulation model. The experiment results demonstrate that the strength and stiffness of the structures were improved by sand-filling under the impact of low energy level, especially for the structures with softer honeycomb core. With the same mass, honeycomb core with smaller cell size and lower height is preferable at low energy level. Localized structural deflection and damaged area were also observed under impact of high-energy level when the core height reached a fixed value. The model of numerical simulation was validated with the experimental results, which can be used in further research.
Abstract:To investigate the energy absorption characteristics and crush behavior of layered aluminum honeycomb, the experiments of layered aluminum honeycomb structure under quasi-static load had been carried out, mainly includes single, double, triple, four layer combinations. The results showed that: the peak force and the mean plateau force of single-layer aluminum honeycomb structure are proportional to the surface density, however they decline slightly with increase of the height; unequal height double layered aluminum honeycomb structure has more advantage in cushion performance; with the increase of layers, the MP ratio will decrease; the combination of placing soft layer between hard layers is better than the others.
HPS (Honeycomb-like Protective Structure) is a newly proposed protective structure filled with sandy soil. In order to investigate the penetration resistance of the structure, numerical simulations based on SPH method had been carried out by using LS-DYNA, which are corresponding to the experiments. The calibrated model leads to reasonable predictions of the dynamic responses and damage modes of the HPS. More situations were carried out taking factors influencing the penetration into consideration, including point of impact, angle of impact, and projectile caliber. Penetration mode was established by analyzing the energy dissipation and investigating the mechanism from the phenomenological viewpoint. Simulation results show that the resisting forces and the torque that act on the long rod projectile would be greater than those acting on the short one when instability occurred. Besides, approximate 45 ∘ angle of impact was formed in the case of off-axis, which has a certain influence on the ballistic stability, resulting in more kinetic energy of projectile dissipating in HPS and less depth of penetration. The kinetic energy of projectile dissipated in sandy soil largely and the strip slightly, and the former was greater than the sum of the latter.
A new type of explosion-resistant biomimetic layered honeycomb structure was designed based on the natural mechanism and biological inspiration, which was mainly composed of a sacrificial layer and a bearing layer. The shock tube device was adopted to analyze the dynamic response of the biomimetic layered honeycomb structure under the action of explosion load in order to obtain the deformation modality, deflection data, and strain time-history curve of the structure. It turns out that the maximum deformation deflection of the back panel of the structure is only 28 mm. Compared with the structure of single-layer honeycomb, the independent sacrificial layer, and bearing layer, the biomimetic layered honeycomb structure has good explosion-resistant performance and can repeatedly bear multiple explosion loads. Besides, equivalent homogenization theory was employed to carry out numerical simulation. The results show that the numerical simulation results are perfectly in line with the results of experiments, and the numerical simulation method is proven to be feasible and effective. Under the action of explosion load, the biomimetic layered honeycomb structure absorbs energy mainly by sacrificial layers that are in layered and staggered arrangement. In addition, the sharp rangeability of the kinetic energy of bearing layer structure indicates that it has the feature of large mass, which can be used as the bearing part of the biomimetic layered honeycomb structure.
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