Energy Absorption Characteristics Research Articles

Investigation on lateral impact resistant performance of aluminum foam-filled 6082-T6 aluminum alloy circular tubes: Experimental and numerical study

Nowadays, the aluminum alloy building structure is at risk of the accidental impact loadings, which seriously threatens the personal security and the safety of the property. However, the existing research on the local lateral impact performance of the aluminum foam-filled tube applied to building structures is limited. In this study, impact tests on 9 aluminum foam-filled tubes with fixed boundaries were conducted by using a drop hammer impact test device to investigate the dynamic performance of the foam-filled tube under local lateral low-velocity impact loadings. The failure modes, impact force histories, displacement histories, and permanent deformation of the foam-filled tubes were obtained and compared with those of the empty tubes under the same impact loading. The finite element (FE) model was also established via the software ANSYS/LS-dyna and the accuracy of the FE method was verified against impact test results. Based on the experimental and numerical results, the aluminum foam-filled aluminum tube shows better lateral impact resistant performance than the empty tube due to the support effect of the aluminum foam on the tube wall by good energy absorption and deformation characteristics. Especially, filling the aluminum foam prevents the generation of cracks for the composite tube near the impact position when the impact energy is high. The influence law of the aluminum foam filler and its density, shape of hammer head on the lateral impact resistant performance of the aluminum foam-filled composite tube was then investigated based on the experimental and numerical results by consideration of the damage level, energy absorption, impact force–lateral displacement relationship, and permanent deformation. By filling the aluminum foam into the empty tube, the energy absorption is improved by up to 67.2% and 44.9%, respectively, when the hammer displacement reaches 20 mm and 40 mm within the impact load condition conducted in this study.

Study and optimization of energy absorption characteristics of a new concave polygon tube

To improve the energy absorption characteristics of the traditional convex polygonal tube and the existing concave polygonal tube, a new evolutionary scheme for the concave polygonal tube was proposed. The energy absorption characteristics of different concave tubes evolved from the common scheme (Scheme-I) and the new evolution scheme (Scheme-II) were studied through quasi-static compression experiments and numerical simulations. The results show that under the same mass, the concave polygonal tube evolved by Scheme-II has better energy absorption characteristics. The folded half-wavelength is smaller at the same compression distance, and compared with the traditional pentagon tube, the energy absorption (EA) of the pentagon concave of Scheme-II (N5E-CT) is improved by 218%, and the crushing force efficiency (CFE) is improved by 69%. Secondly, the mean crushing force of convex and concave tubes is derived and verified by the folded element theory. The mode of deformation of concave tubes under different structural sizes was investigated, and the size range within which the concave tube can remain stable was obtained. In addition, the evolution of the specific energy absorption (SEA) of the concave tubes was explored, and the SEA and the number of structural sides (N) show a trend of first increasing and then decreasing. Finally, the multi-objective optimization of the pentagon concave tube with excellent energy absorption characteristics was conducted, and the initial peak crushing force of the optimized structure was reduced by 19.92%.

Foaming Behavior of Microsized Aluminum Foam Using Hot Rolling Precursor

Aluminum foam that is lightweight with high specific strength, high energy absorption and other characteristics can be used in aerospace, transportation, machinery manufacturing and other fields. The PCM method is usually used to prepare closed-cell aluminum foams. The microsized aluminum foams made by this process can solve the non-uniform pore structures caused by liquid drainage during the foaming process of large aluminum foams. The surface morphology and internal pore structure of microsized aluminum foams are affected by the quality of the precursor used for foaming. In this paper, foamable precursors were obtained via either hot rolling or hot extrusion and subsequently foamed. By analyzing the micromorphology and foaming process of the precursor, the influence of the technological method on the macroscopic pore structure of the final aluminum foam was studied. The results show that the aluminum powder particles in the precursor prepared with the hot rolling method had metallurgical bonding, and the outer surface was dense, with almost no porosity and holes in the interior. The microsized aluminum foam obtained after foaming was smooth in appearance, and the internal pore structure was round and uniform. The reason is that during the foaming process of microsize aluminum foam, the foaming agent was evenly distributed in the precursor of the hot rolling process because of its compact structure. During the foaming process, the decomposed gas of the foaming agent will not escape, and the evenly distributed foaming agent tends to nucleate in situ. In the process of rapid foaming, the pressure in the bubble is enough to resist the liquid drainage phenomenon caused by gravity, and the growth direction of the gas core is isotropic, which promotes the foam structure to be more rounded and uniform.

A novel energy-absorbing composite structure with layers of basalt fiber fabric constraining waste brick particles and foam concrete

To seek a new way of recycling the waste brick, a novel energy-absorbing composite structure, consisting of the top layer of basalt fiber fabric constrained waste brick particles (BFCBP) and the bottom layer of foam concrete, is proposed to realize the purpose of the multi-level protection. First of all, the quasi-static compressive test is conducted on the BFCBP specimens with three different height-to-diameter ratios and the foam concrete specimens with four different densities and three height-to-diameter ratios, and their energy absorption performance is evaluated by the test data. The results show that the height-to-diameter ratio of the BFCBP specimen as well as the density and height-to-diameter ratio of the foam concrete specimen have a significant influence on their failure mode and energy absorption. Then after a reasonable combination of the two layers of BFCBP with a height-to-diameter ratio of 1.0 and foam concrete with a density of 700 kg/m3 and a height-to-diameter ratio of 0.5, the quasi-static and dynamic compressive tests are conducted on the energy-absorbing composite structure, and its deformation process, energy absorption, and load transfer under different compressive velocities are experimentally investigated. The test results show that the composite structure subjected to quasi-static and dynamic compressive loading demonstrates layered compression deformation and two-phase energy absorption characteristics, which implies that the proposed composite structure could provide multi-level protection by its staged energy absorption.

Crushing responses and energy absorption of bionic inspired corrugated honeycombs

To improve the energy absorption of traditional structures, impact resistant natural materials are usually mimicked to develop novel structures with desirable energy absorption. In this work, inspired by the unique 3D corrugated microstructure of vascular bundles in pomelo peel, a new design of honeycomb structure with corrugated characteristics is proposed. Further, motivated by special nodal bulkhead architecture of bamboo, layered honeycombs with diaphragms are designed and fabrication by metal 3D printing technology. The quasi-static and dynamic crushing responses and energy absorption characteristics of six types of bio-inspirational honeycombs (ISWH, LSWH, ISCH, LSCH, IPCH and LPCH) are studied using quasi-static testing machine and dynamic drop-weight impact experimental systems. To investigate the effect of impact speed on the crashworthiness performance of the honeycombs, the tests of the honeycombs impacted by the drop-weight with two different mass (106.07 and 59.60 Kg) and three impact velocity (V1=6.23, V2=8.82 and V3=11.77 m/s), respectively, are performed. The experimental results indicate that the crush failure mode of the layered honeycombs is more regular than that of the integrated honeycombs. Failure of all layered honeycombs occurs first at the junction of the honeycomb and diaphragms. Under impact loading, the layered corrugated wall honeycombs exhibit a greater final crushing distance than their corresponding integrated honeycombs. The design of corrugated wall can effectively reduce the initial peak force of the integrated honeycombs, while the layered honeycomb design also facilitates the reduction of the initial peak force, thus avoiding damage to personnel or equipment from excessive peak collision forces. The layered design will reduce the specific energy absorption of the integrated honeycombs in most cases, but a reasonable combination of layered and corrugated wall design can also effectively increase the specific energy absorption of the honeycombs under a specific loading speed. And, the layered design can also effectively improve the crush force efficiency of the corresponding integrated honeycombs.

Mechanical Energy Absorption Ability of Titanium-Based Porous Structures Produced by Various Powder Metallurgy Approaches.

Porous materials are very efficient in absorbing mechanical energy, for instance, in combined armor, in order to improve the anti-ballistic protection characteristics. In the present study, porous titanium-based structures were manufactured via three different powder metallurgy methods using titanium hydride (TiH2) powder, which provided activated sintering, owing to dehydrogenation. The emission of hydrogen and shrinkage of powder particles on dehydrogenation also added an additional potential to control the sintering process and create desirable porosities. TiH2 powder was sintered with additions of NaCl or ammonium carbide as pore holding removable agents, while highly porous Ti-Al structures were formed via liquid phase reactive sintering of TiH2 and Al powders. The microstructures and porosities of sintered dehydrogenated titanium and Ti-Al structures were comparatively studied. Mechanical characteristics were evaluated using compression testing with strain rates varying from quasi-static to high levels. The resonant frequency method was also employed to determine damping parameters and elastic modulus of these materials. All testing methods were aimed at characterizing the energy-absorbing ability of the obtained porous structures. The desired strength, plasticity and energy-absorbing characteristics of porous titanium-based structures were assessed, and the possibilities of their application were also discussed. Based on the obtained results, it was found that porous titanium materials produced with the use of ammonium carbonate showed promising energy absorption properties.

A systematic design of multifunctional lattice structures with energy absorption and phononic bandgap by topology and parameter optimization

ABSTRACT Lattice structure can realize excellent multifunctional characteristics because of its huge design space, and the cellular configuration directly affects the lattice structural performance and lightweight. A novel energy-absorbing multifunctional lattice structure with phononic bandgap is presented by topology and parameter optimization in this paper. First, the two-dimensional (2D) cellular configuration is lightweight designed by using independent continuous mapping (ICM) topology optimization method. The 2D cell is reconstructed by geometric parameters and rotated into a three-dimensional (3D) cell by using chiral shape to achieve bandgap. Subsequently, the surrogated model with energy absorption as the object and first-order natural frequency as the constraint is established to optimize a parametric 3D cell based on the Response Surface Methodology (RSM). Finally, the lattice structures are assembled with dodecagonal staggered arrangements to avoid the deformation interference among the adjacent cells. In addition, the lattice structural energy absorption and bandgap characteristics are analyzed and discussed. Compared to Kelvin lattice structure, the optimal lattice structure shows significant improvement in energy absorption efficiency. Besides, the proposed design also performs well in damping characteristics of the high-frequency and wide-bandgap. The lattice structural optimization design framework has great meaning to achieve the equipment structural lightweight and multi-function in the aerospace field.

Model test on deformation and failure mechanism of tunnel support with layered rock mass under high ground stress

To control the large deformation of the Changning Tunnel, based on the constant resistance and energy absorption characteristics of the NPR anchor cable, first, through the physical model test, the mechanics of the NPR anchor cable controlling the deformation of the floor heave was studied, including the temperature field, strain field, and displacement field during the tunnel excavation and loading process. Then, through field tests, the control effect of NPR anchors was studied. The results of the model test show that under the support of NPR anchor cables, with the increase of geostress, the asymmetric deformation of the vault and floor is obvious. During the loading process, the shallow rock mass pressure strain area at both ends of the floor is larger, squeezing the floor and causing strong temperature changes and floor heave failures of the rock mass, while the deep rock mass strain value changes smoothly and is relatively stable. After the axial force of the NPR anchor cable transitions from the growth stage to the stable state, the rock mass deformation converges and stops growing. In the field test, the NPR anchor cable can reduce the primary support deformation from more than 2000 mm to 108 mm, and reduce the stress on the support structure, which is helpful in avoiding the risk of initial support deformation and secondary lining damage in the deep-buried, layered rock mass tunnels.

Energy Absorption Characteristics of Fused Deposition Modeling 3D Printed Auxetic Re-entrant Structures: A Review

Energy Absorption Characteristics of Fused Deposition Modeling 3D Printed Auxetic Re-entrant Structures: A Review

Study on Sound Absorption Performance of Aluminum Foam Combination

Aluminum foam is a kind of new material with a large number of holes distributed in aluminum alloy. It has the characteristics of lightweight, sound absorption, energy absorption and vibration reduction, and other porous materials. Aluminum foam has good acoustic performance. However, its excellent sound absorption ability is only reflected in the middle and high-frequency bands. Besides, the low-frequency sound absorption ability is very poor and the frequency band is narrow. Therefore, in this paper, different types of perforated aluminum foams with different parameters are combined to explore the influence on acoustic performance and find that the combination of large porosity perforated sample and aluminum foam has a better sound absorption effect. The unperforated sample is placed in front of the perforated sample to improve the sound absorption coefficient of the low and medium frequencies. Finally, different types of perforated aluminum foam samples were properly combined, and it was found through the test that almost all sound waves in the band of 1200 HZ~2000 Hz could be absorbed by the combined structure.

The energy-absorbing characteristics of two-dimensional periodic self-reinforced polypropylene (SRPP) sandwich panel

The energy-absorbing characteristics of two-dimensional periodic self-reinforced polypropylene (SRPP) sandwich panel

Impact of Addition of Fly Ash (as Sand Replacement) and Polypropylene Fibers on Energy Absorption Characteristics of Foam Concrete

Abstract Foam concrete has recently piqued the interest of defense engineering because of its innovative properties of absorbing energy, softening impact, exhausting oscillation, and lowering stress amplitude behavior. However, only a few investigations on foam concrete’s mechanistic behavior and energy absorption properties have been published. This study examines the effects of adding fly ash (sand replacement) and polypropylene fibers to foam concrete with design densities of 1,000 and 1,500 kg/m3 on fresh state features (stability and consistency), mechanical properties, and energy absorption capacities. The consistency of foam concrete increases with the addition of foam and fly ash, but the inclusion of fibers has a significant impact. Though the addition of fibers reduced the compressive strength of foam concrete, the bonding of fibers with the matrix is strengthened in fly ash–based mixes, resulting in increased strength, showing the synergistic effect. An improvised low-velocity drop-weight impact test is carried out on foam concrete target slabs produced with various mix compositions to investigate the impact mitigation properties of foam concrete under impact loading. The energy absorption capacity of different mixtures of foam concrete specimens is found to vary between 0.3 and 1.18 J using the conservation of energy law and assuming no energy losses. Because of the availability of sufficient bubble space for crushed debris and the better impact resistance provided by the fibers, mixes with more air and fibers displayed relatively more energy absorption. To examine the mixes based on the local area effect of impact loading, observations on both energy absorption and failure mechanism are carried out.

High velocity impact response of sandwich structures with auxetic tetrachiral cores: Analytical model, finite element simulations and experiments

This paper investigates the energy absorption and deformation characteristics of sandwich structures with auxetic tetrachiral core under high velocity projectile impact. The finite elementmodel of the structure is developed using the Johnson-Cook material model and is used to studythe effects of projectile impacts forvelocities between150 and 450 m/s. TheFE model is validated usingin-houseexperiments on 3D printed PLA sandwich with tetrachiral core under hemispherical projectile impact and also using experimental datareported in the literature. Further, a semi-analytical model is developed to estimate the residual velocities and energy absorption of sandwich structure under blunt projectile impact, which shows good agreement with the FE results with an error of less than 8%. Finally, the performance of the sandwich structure with tetrachiral cores is studied under projectile impact for velocities ranging from 150 to 350 m/s and compared with sandwich structures with re-entrant and double arrowhead cores. The results show that for velocities above the ballistic limit, the energy absorbed by the facesheets, and core are nearly constant and is greatest for blunt projectile impact, followed by hemispherical, ogive, and conical geometries. Furthermore, sandwich structures with auxetic cores exhibit better energy absorption characteristics compared to those with hexagonal honeycomb cores.

Energy absorption characteristics of the bionic lotus petiole structure under transverse load

Porous structures are often used as energy absorbing devices due to their light weight and high strength; therefore, the mechanical properties and collapse behavior of porous structures under various loads have attracted much attention. In this paper, two bionic lotus petiole structures: 12-wells original structure (Os-12w) and 13-wells original structure (Os-13w) are proposed to improve the energy absorption properties of porous structures, which are inspired by the light weight and collapse resistance of lotus petiole. Then a comparative study of Os-12w, Os-13w, hollow square tube and hollow circular tube based on quasi-static mechanical experimentally(loading speed is 3 mm/min) validated finite element models was carried out to explore the energy absorption characteristics of different structures under lateral loading. The results showed that the specific energy absorption (SEA) of Os-12w and Os-13w increased by about 88.9% and 77.8%, respectively, and the crushing force efficiency (CFE) increased by about 178.8% and 178%, respectively, compared with the hollow square tube. Compared with the hollow circular tube, the peak crushing force (PCF) of Os-12w and Os-13w were reduced by about 28.2% and 36.8%, respectively. Collectively, Os-12w has a greater energy absorption potential than Os-13w. The simulation results of the experiment explain why the energy absorption performance of the bionic structure is better than that of the hollow tube. Then, through further simulation analysis, the effects of the bearing angle and quarter windmill-like structural parameters on the energy absorption characteristics of Os-12w were explored. Valuable suggestions and guidance are provided for the subsequent development of thin-walled porous structures.

Early-age mechanical properties and constitutive model of polystyrene concrete under impact load

The dynamic mechanical tests of polystyrene concrete with ages of 12 h, 24 h and 36 h and 28 d were carried out by Φ 100 mm SHPB equipment. The effects of strain rate and age on dynamic mechanical properties of polystyrene concrete were analyzed in terms of the relationship between strain rate and impact velocity, strength characteristics, deformation characteristics and energy absorption characteristics. And based on Saenz model, the early-age dynamic constitutive model of polystyrene concrete was constructed. The results show that the strain rate of polystyrene concrete is positively correlated with the impact velocity. At the same impact velocity, the strain rate of polystyrene concrete decreases with age. The strength characteristic indicators, deformation characteristic indicators and energy absorption characteristic indicator of polystyrene concrete all have strain rate strengthening effect, and all these indicators and the strain rate sensitivity of these indicators increase with age. Polystyrene concrete has good deformation and energy absorption characteristics at early age. At the age of 36 h, the peak strain, ultimate strain and specific energy absorption of polystyrene concrete can reach 77∼80%, 95∼106% and 86∼92% of that at the age of 28 d, respectively. The constructed dynamic constitutive model is reasonable and reliable, and it can be used to describe the mechanical behavior of polystyrene concrete at early age under impact load.

Crashworthiness optimization for cutting energy-absorbing structures based on the multiobjective G-CBW method

The energy absorption structure of a train is an important part of passive safety protection during train collisions and is the last line of defense to protect both passengers and trains. In the design process of a train energy absorption structure, improved stability and greater energy absorption capacity is required. A cutting anti-climbing energy absorption structure offers good stability and energy absorption in a collision, but it can easily generate considerable heat in the energy absorption process. Therefore, it is important to conduct thermal–solid coupling simulations and crashworthiness optimization for cutting energy absorption structures. To improve the passive safety protection capability of high-speed trains, this paper experimentally and numerically explored the crashworthiness of a cutting-type energy-absorbing structure composed of an anti-creeper device, an energy-absorbing tube, cutting knives and knife-supporting tools. By adopting the Johnson–Cook material model, a finite element model was developed to study its energy absorption characteristics in a coupled heat–solid state. The effects of cutting depth (D), cutting knife front angle (A) and cutting width (W) on energy absorption (EA), cutting platform force (Fmean) and peak cutting force (PCF) were analyzed based on the validated simulation model. The results showed that EA, Fmean and PCF increase with increasing D and W, while EA, Fmean and PCF decrease with increasing A. The GRSM was employed as the optimization algorithm, and a gain matrix–cloud model optimal worst method (G-CBW) multiobjective decision algorithm was proposed to obtain the most satisfactory configurations from the Pareto front solution. The relative errors from the optimal and finite element results of EA, Fmean and PCF were 3.5%, 2.1% and 2.2%, respectively. All the crashworthiness indicators were improved considerably.

Energy absorption characteristics analysis of multicellular columns based on the origami centripetal folding method

In order to improve the crashworthiness of traditional Thin-Walled Struct, a new method for designing multicellular tubes is presented in this paper. In this work, multicellular columns based on origami centripetal folding method (MCOCFM) are proposed. The cross section of MCOCFM is designed in the way of origami. The mechanical properties of MCOCFM under uniaxial compression are analyzed by numerical simulation. Studies have shown that increased levels and wall thickness facilitate energy absorption. In addition, the theoretical prediction of MCF is in good agreement with the simulation results. Compared with some existing structures, MCOCFM has better crashworthiness.

Sustainable composites with ultrahigh energy absorption from beverage cans and polyurethane foam

The worldwide annual consumption of metal beverage cans is enormous. Reusing these discarded empty beverage cans (EBCs) as an energy absorber for kinetic energy absorption would be highly beneficial for promoting energy savings, reducing greenhouse gas emissions, and establishing a circular economy. However, EBCs are susceptible to deformation in an undesirable failure mode under axial crushing loads, which is unfavorable for energy absorption. This study demonstrates the effectiveness of combining empty cans with polyurethane (PU) foam to enhance the energy absorption performance of EBCs. The study develops low-cost and sustainable composite structures (SCSs) from waste beverage cans. Surprisingly, the specific energy absorption (energy absorption per unit mass) of the SCSs is 2.44 times that of the EBCs under axial quasi-static compression. The average axial crushing force of SCSs is approximately 23.4 times the weight of the empty can itself. Furthermore, the SCSs exhibit excellent crashworthiness performance in various dynamic impact scenarios and superior energy absorption characteristics compared to other typical tubular composites and metamaterials. This study demonstrates an extremely feasible approach for developing next-generation eco-friendly and high-performance energy-absorbing composite materials.

Biomimetic 4D printing of dome-shaped dynamic mechanical metamaterials

The dome shaped structures of natural organisms can provide design inspiration for impact resistant structural materials. Most of the existing biomimetic dome shaped impact resistant materials are directly formed using 3D printing technology, and the samples cannot dynamically adjust the impact resistance properties in the various applications. Herein, 4D printing of fused filament fabrication is employed to form flat structures with different structural patterns via programming the printing process parameters, which can be deformed into biomimetic dome structures with dynamic thermal stimulation treatment. The thermal stimulation treatment can drive the dynamic transformation of 2D planar structures into 3D structures, and the higher the thermal stimulation temperature, the greater the degree of eminence and the denser the structure under the same experimental conditions. The thermal stimulation temperature and the mechanical properties of the structural samples show a certain positive correlation. In addition, different design structural patterns have different compressive mechanical properties. The more the number of circular units, the more obvious the energy absorption characteristics. The impact-resistant biomimetic structures can be applied to the surface strengthening and cushioning of various weapons, vehicles, heavy equipment, and launch structure.

Impact resistance capacity and degradation law of epoxy-coated steel strand under the impact load

Abstract As the main load-bearing component of the bridge structure, the cable is damaged by the impact from time to time, so it is very important to clarify its impact resistance capacity. Based on the method of the drop-weight test, this article mainly studies the degradation law of the mechanical properties of epoxy-coated steel strand (ECSS) under the impact load. Through the impact test of ECSS under different working conditions, the influence law of prestress, impact energy, initial defects and other factors on the impact resistance of the steel strand was revealed. Then, the difference of the impact resistance of ECSS and ordinary steel strand (OSS) was verified under the same impact conditions. Finally, the failure mechanism and the residual-bearing capacity of ECSS were analyzed through the secondary impact test. The results show that the initial prestress is helpful to improve its impact resistance when it is less than 0.11 f u {f}_{{\rm{u}}} , and exceeding this value will accelerate its failure process. The effect of impact height on the strain at the impact point of ECSS is significantly greater than that near the anchor end. ECSS has better energy absorption characteristics than OSS. The impact resistance of ECSS with initial defects is very sensitive to the impact energy. The influence on outer strand in the secondary impact is significantly higher than the central strand, and its residual tensile capacity still has 0.85 f u {f}_{{\rm{u}}} .