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The battery-pack system of electric vehicles is prone to collide with low obstacles on the road, causing battery short circuits and even explosions. It poses a great safety threat to passengers and drivers. The honeycomb structure's high energy absorption and lightweight properties have made it a popular choice in the automotive industry. This paper designs different bio-inspired honeycomb structures to a battery-pack system of electric vehicles to improve the crashworthiness performance. The effects of different bio-inspired honeycomb structures on the crashworthiness of a battery-pack system during frontal impact are analyzed based on a nonlinear finite element model. First, the geometric parameters of seven different bio-inspired honeycomb individual units are described. The overall structure of the honeycomb is applied to a battery-pack system. Second, the nonlinear finite element model of a battery-pack system and honeycomb structures are established and verified. Then, collision simulations are conducted. The deformation and the maximum stress of a battery-pack's bottom shell are computed. The energy absorbed by the honeycomb structures during frontal impact are investigated. The results indicate that the proposed bio-inspired honeycomb structure mimicking grass stems improves the safety performance of battery-pack systems most. Finally, a parametric design is carried out on the bio-inspired honeycomb structure. The effects of wall thicknesses and the number of replacement hexagons on the crashworthiness performance are analyzed. The honeycomb structure preforms best when thickness is 1 mm and the number of replacement hexagons is 2 and 4. The optimized bio-inspired honeycomb structure reduces the deformation of the battery-pack' bottom shell by up to 30%, and maximum stress by 10%. • The deformation, maximum stress, and energy absorption are investigated. • The effects of seven bio-inspired honeycomb structures are analyzed. • Parametric design is carried out to further improve the crashworthiness performance. • The deformation of the bottom shell can be reduced by up to 30%. [ABSTRACT FROM AUTHOR]

Tensile mechanical properties of a zero Poisson’s ratio（ZPR） honeycomb structure suitable for morphing application is studied. A theoretical method for calculating in-plane tensile modulus of ZPR cellular structures is proposed based on energy method, and the impacts of the unit cell geometrical configurations on in-plane tensile modulus is studied systematically based on finite element （FE） simulation. Then, experimental tests validate the feasibility and effectiveness of the theoretical and FE analysis. In addition, to describe the nonlinear deformation regularity of ZPR cellular structures, FE simulation with using aluminum alloy and steel as the workpiece is built and the relationship between the deformation and the residual strain is studied. Results show that these cell geometric parameters and material performance provide different contributions to the effective mechanical properties of ZPR cellular structures, which suggests that the in-plane mechanics of ZPR cellular structures can be manipulated by designing cell geometrical parameters and material selection. Furthermore, when selecting the base material, in order to take into account both the “in-plane” stiffness and the “out-of-plane” load-bearing capacity, not only materials with a small Young’s modulus should be selected to reduce its driving force, but also materials with a large elastic section should be selected to reduce residual deformation. [ABSTRACT FROM AUTHOR]

A model able to predict the delamination mechanisms of composite honeycomb structures under thermal loading is presented. The use of a simulation software for some applications may not be sufficient to obtain the results expected; hence, the interest in developing modular calculation codes which would allow one to determine the rigidity matrix of a honeycomb panel, the deformation of its members, the field of shear strains, strains, and stresses in the panel plane on varying the physical parameters and checking the strength of each layer and of the entire panel. In order to test the reliability of the program developed, the results obtained are compared with those given in the literature. A specific model of Young's modulus under thermal loads is proposed, which takes into consideration the heat flux function, the thermal conductivity, the convection heat-transfer coefficients of the surrounding area inside and outside the panel, the exchange area in contact with air, the thickness of the honeycomb core, the upper and lower skins, and the adhesive layer. To verify the fracture strength of each panel, the Tsai-Wu criterion is used. [ABSTRACT FROM AUTHOR]

Abstract: Mechanical strain induced tunability in two-dimensional (2D) honeycomb structures of MoX2 (X=S, Se, Te) with a focus on dielectric properties have been investigated in the framework of density functional theory. Mechanical strains reduce the band gap of considered semiconductors by causing a direct-to-indirect band gap transitions and finally rendering them into metal at critical value depending on the types of applied strain. The ultimate tensile strength estimated for MoS2, MoSe2 and MoTe2 monolayers is , and respectively. Band-gap deformation potentials have been found to posses strong dependence on the types of applied strain. Small tensile strains increases the exciton binding energies which can have importance in the applications of optoelectronics. Dielectric properties too get influenced by the type of applied strain as well as the type of material. Imaginary part of dielectric function ( ) shows redshift in the structure peak energy on the application of strains with significant dependence on the types of applied strain. Static dielectric constant ( ) has been found to increase with the increase of tensile strains (both uniaxial and biaxial) and asymmetric biaxial strain. On the other hand, decreases for smaller magnitude of compression strains and show increase at higher magnitude. The change in the magnitude of particularly for compression strains remain material specific. [Copyright &y& Elsevier]

Progressive deformation of honeycomb structures subjected to in-plane loading was approximately analyzed by using the collapse modes of hexagonal unit cells. The collapse modes were categorized as freely compressive, restricted compressive, and shear. Moreover, there were five characteristic deformation patterns, namely deformation bands. Average stresses of the collapsing honeycomb models were evaluated in terms of the plastic collapse stress per hinge and total number of hinges of progressively arising deformation bands. The displacements of the models were obtained by multiplying the displacement per cell with the number of collapsed cells. The present method was used to analyze progressive deformation of typical honeycomb structures. The validity of the stress-displacement relations derived for some structures was confirmed by comparing them with finite element method (FEM) results. Our method is much simpler than FEM but just as effective. [ABSTRACT FROM AUTHOR]

Materials exhibiting negative linear compressibility display the very unusual and unexpected property of expanding in at least one direction when placed under compressive hydrostatic stress. Here, it is shown that this property may be manifested by systems having high positive Poisson’s ratios (non-auxetic), including non re-entrant hexagonal honeycombs and wine-rack models where deformation primarily involves changes in the angles between the ribs of the structures. [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]

• Thermo-mechanical buckling analysis of a honeycomb plate is studied. • Quasi-3D hyperbolic shear deformation theory which accounts for stretching effect have been used. • Influences of geometrical parameters, hygrothermal conditions, and different material parameters are explored. Halpin-Tsai and extended rule of mixture (ERM) schemes are used to evaluate the effective material properties of composite face sheets of a micro-scaled sandwich rectangular plate, to assess its thermo-elastic buckling behavior, in the current paper. For more details, it should be added that under evaluation model, which is resting on a Pasternak elastic foundation, is a honeycomb micro structure which is made of Nomex or Glass Phenolic and, to integrity, is patched with two same composite layers including graphene nanoplatelets (GNPs) dispersed through Epoxy resin. Great novelty of quasi-3D hyperbolic shear deformation theory (QHSDT) which accounts for stretching effect, virtual displacement principle, and modified couple stress theory (MCST) produced a good motivation to hire it to extract equations related to the current sandwich micro plate. Finally, variations of critical loads of thermal and mechanical buckling considered in figures and tables to examine the effect of different parameters' changes on them. As an example, based on acquired results, the sensitivity of thermo-mechanical critical buckling loads to the internal aspect ratio of honeycomb core ϕ 0 and force intensity distributions is proved where force intensity enhancement is caused critical buckling load reduction. [ABSTRACT FROM AUTHOR]