This paper presents details and brief results of an experimental investigation on the response of square metallic sandwich panels with a cellular core under blast loading. Based on the experiments, ...corresponding finite element simulations have been undertaken using the LS-DYNA software. Detailed description of the models and simulation results is presented. In the simulation work, the loading process of explosive and response of the sandwich panels have been investigated. The blast loading process includes both the explosion procedure of the charge and the interaction with the panel. The structural responses of sandwich panels are studied in terms of two aspects: (1) deformation/failure patterns of the specimens; and (2) quantitative assessment, which mainly focuses on the permanent centre point deflection of the back face of the panels. In addition, a parametric study has been carried out to examine the contribution of plastic stretching and bending on the deformation history of the sandwich panels, as well as the effect of boundary conditions. A good agreement has been obtained between the numerical and experimental results, and thus the proposed FE model can be considered as a valuable tool in assessing and understanding the deformation/failure mechanism and predicting the dynamic response of square metallic sandwich structures subjected to blast loading.
In this paper curved sandwich panels with two aluminium face sheets and an aluminium foam core under air blast loadings were investigated experimentally. Specimens with two values of radius of ...curvature and different core/face sheet configurations were tested for three blast intensities. All the four edges of the panels were fully clamped. The experiments were carried out by a four-cable ballistic pendulum with corresponding sensors. Impulse acting on the front face of the assembly, deflection history at the centre of back face sheet, and strain history at some characteristic points on the back face were obtained. Then the deformation/failure modes of specimens were classified and analysed systematically. The experimental data show that the initial curvature of a curved sandwich panel may change the deformation/collapse mode with an extended range for bending dominated deformation, which suggests that the performance of the sandwich shell structures may exceed that of both their equivalent solid counterpart and a flat sandwich plate.
This work reports on the in-plane crushing behaviour of second-order hierarchical honeycombs with triangle substructures (SHT). Here, cell walls of a conventional hexagonal honeycomb were replaced ...with two-layer equilateral triangles as substructures. Finite element (FE) simulations and analytical modelling were conducted, and a good agreement was found between FE and analytical results. The response of SHT was compared with that of other patterned honeycombs. Three deformation modes were observed under different loading speeds, and critical velocities for mode transforming were obtained qualitatively. The effect of loading speed and relative density on crushing stress and energy absorption capacity was also discussed.
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•The indentation of honeycombs was conducted at strain rates from 10−3 to 102s−1.•Plateau stress of honeycombs increased with strain rate and honeycomb density.•Total energy and ...tearing energy in indentation increased with strain rate.•Empirical formulae were proposed for tearing energy in terms of strain rate.
The present paper details the first extensive study of the dynamic out-of-plane indentation of aluminum honeycombs at a range of different loading velocities. Dynamic and quasi-static mechanical properties of honeycombs were comparatively analyzed to investigate the strain rate effect on both mean plateau stress and energy absorption. Indentation and compression tests of three types of HEXCELL® 5052-H39 aluminum hexagonal honeycombs were tested using MTS and high speed INSTRON machines at strain rates from 10−3 to 102s−1 respectively. The tearing energy was calculated as the difference in energy dissipated in indentation and compression of the same type of honeycomb. It was found that tearing energy was affected by strain rate and nominal density of honeycomb. Empirical formulae were proposed for tearing energy in terms of strain rate.
It is widely known that the demand for lightweight structures with excellent energy absorption capacity is paramount in numerous engineering applications. Many publications have revealed that ...corrugated structures can collapse in a relatively controlled manner with a uniform force-displacement response and have remarkable energy absorption efficiency when compared with traditional structures without corrugations. The present work provides a comprehensive overview of recent advances in the development of corrugated structures for energy absorption applications, also considering the effects of corrugation characteristics on their crashworthiness. Such advanced energy absorbers include corrugated tubes, corrugated tapered tubes, corrugated beam and plates, corrugated honeycombs, corrugated core sandwich panels and other hybrid structures with complex corrugations. This review demonstrates that thin-walled structures with introduced corrugations can achieve more efficient and effective energy absorption. Finally, contemporary challenges of design and manufacture are discussed, as well as future directions for corrugated structures. This synopsis provides a useful platform for researchers and engineers designing corrugated structures for energy absorption applications.
•This work provides an overview of corrugated structures for energy absorption.•The corrugation configuration has strong effects on the structure's crashworthiness.•The introduction of corrugation improves the energy absorption efficiency.•The review provides a valuable platform for researchers to discover new research lines for corrugated structures.
In this study, the mechanical characteristics of the graded origami bellows were numerically investigated and experimentally validated. Two graded geometric parameters were considered: pre-folding ...angle (
θ
) and layer height (
L
e
). The sensitivities of the deployment process and energy absorption efficiency of origami bellows to variations in
θ
and
L
e
under quasi-static loading and dynamic loading were numerically investigated. Results show that the origami bellows with positive gradients exhibited progressive deployment process. More than one deformation mechanism was triggered during deployment, indicating a mixed non-rigid deployment mode. A large gradient of
θ
had a notable effect on the energy absorption efficiency. Both specific energy absorption (
SEA
) and mean tensile force (
P
m
) decreased as the gradient of
θ
increased. Although the gradient of
L
e
was insensitive to the force response, the
SEA
decreased as the gradient of L
e
increased. The dynamic behavior of the graded models indicated that both the initial peak force and
SEA
were affected by the graded parameters. In general, the proposed graded origami bellows show a controllable deployment process and a stable force response under axial tension.
ABSTRACTBased on the principle of local resonance and the strategy of hybrid design, in this paper we propose three truss-plate hybrid multifunctional lattice metamaterials featured by the cubic cell ...topology with a central truss-plate unit connected by the elastic beams to the eight corners. Finite element (FE) simulations were validated by experimental tests on specimens made of TPU substrate material through SLS additive manufacturing technique. At the relative density of 0.31, the specific energy absorption reaches 2.71 J/g, the bandgap width reaches 2.624 KHz, and the elastic wave transmission attenuation at 1400 Hz frequency reaches – 270 dB. Parametric analyses were carried out to investigate the effects of different geometric parameters on the performance indicators. These results highlight the proposed truss-plate hybrid metamaterial as an intriguing multifunctional material with excellent performances in both energy absorption and vibration attenuation, that can be applied to scenarios with multiple engineering requirements.
▶ Compressive behavior of closed-cell foam at medium strain rates was studied. ▶ The High Rate Instron Test System was used to maintain a constant loading rate. ▶ Plateau stress and energy absorption ...capacity are remarkable dependent on strain rate.
Compressive behavior of closed-cell aluminum alloy foams at strain rates of 10−3–450s−1 has been studied experimentally. The fully stress–strain curves of specimens at medium strain rates were obtained using the High Rate Instron Test System, which can maintain a constant loading rate. The experimental results show that plateau stress and energy absorption capacity are remarkable dependent on strain rate, while the densification strain has a negligible dependence.
This paper is concerned with the plastic energy absorption behavior of expansion tubes under axial compression by a conical–cylindrical die. The experiments and numerical simulation using FEM are ...presented in this paper. Experiments were conducted on circular 5A06 aluminum tubes with an internal radius fixed at 22.5
mm and different thicknesses between 1 and 5
mm; the tubes were pressed axially onto a series of conical–cylindrical dies each with a different semi-angle from 5° to 20°, where the radius of the cylindrical part was 24
mm. A numerical analysis was performed to investigate the tube deformation and the friction between the tube and die. A good fit of the experimental data was obtained by taking the value of the friction coefficient
μ=0.05. Based on these experimental and numerical results, characteristics of driving force–stroke curves in different deformation modes are discussed in detail. Effects of tube dimensions and semi-angle of the die on steady-state force and energy absorption efficiency are also presented. Based on these experimental studies, a theoretical analysis to explain the deformation mechanisms of the tube expanded by a die is carried out and will be given in a subsequent paper
1.
Mechanical response and energy absorption of aluminium foam sandwich panels subjected to quasi-static indentation loads were investigated experimentally. These sandwich panels consisted of two ...aluminium face-sheets and a closed cell aluminium foam core (ALPORAS®). Quasi-static indentation tests were conducted using an MTS universal testing machine, with sandwich panels either simply supported or fully fixed. Force–displacement curves were recorded and the total energy absorbed by sandwich panels was calculated accordingly. Videos and photographs were taken to capture the deformation of top face-sheets, foam cores and bottom face-sheets. Effects of face-sheet thickness, core thickness, boundary conditions, adhesive and surface condition of face-sheets on the mechanical response and energy absorption of sandwich panels were discussed.
