High Energy Absorption Capacity Research Articles

Influence of ternary hybrid fibers on the mechanical properties of ultrahigh-strength concrete

Ultra-high performance concrete (UHPC), an advanced class of fiber-reinforced cementitious material with extraordinary mechanical properties, low permeability, shrinkage and creep, and high energy absorption capacity, has seen steady increase in use, with applications covering construction of new members and retrofit of existing ones. Fibers are added in the UHPC mix to bridge cracks, carry tensile stresses, and contribute greatly to member ductility and load capacity. Hybrid fibers comprising micro and macro types are beneficial where the first type resists microcracking and the second targets macrocracking. This study investigates the effects of blending three fiber types, namely, hooked-end steel (referred to as type 1, representing macro fibers class), straight-end steel (type 2, intermediate size fibers), and carbon (type 2, micro size fiber), on the mechanical properties of UHPC. Experimental tests were performed to characterize the following mechanical properties: flowability, compressive strength, tensile strength, flexural strength, modulus of elasticity, and dry shrinkage. The primary variable in the tests was the blending of different fiber types, using either a unary form of type 1, a binary form of type 1 and 3 or type 2 and 3, and a ternary mix of all three types, at 1.56% dosage by volume. The mix with ternary fibers yielded a compressive strength, tensile strength, flexural strength, and modulus of elasticity that is 14%–17%, 14%–16.8%, 43.66%–22.16%, and 12%–16%, larger than the same respective properties of the mix with unary fibers. In addition, ternary fibers increased the cohesiveness of the mix by 17% and 26% compared to unary fibers.

Investigation of New Energy Absorbing Mechanisms Used to Fix Rock Bolt Plates

In this study, different plate fixing designs were tested in order to improve rock bolting performances. Instead of commonly used steel nuts, different plate fixing designs were investigated by both laboratory and site studies. In addition, the usability of nuts and energy absorbers made of the polyamide type engineering polymer was investigated to assess whether they are advantageous for the aim of supplying high-energy absorbing features. In this experimental study, deformation-controlled load tests were carried out to evaluate the bearing and energy absorption capacities of totally eight different groups of specimens. According to the findings from this study, use of the polyamide material with steel nuts as an energy absorber material, rather than using instead of steel nuts supplies good results. As another outcome, it has been determined that use of proper washers between steel nuts and polyamide absorbers can significantly improve the energy absorption performances. It has been evaluated that the energy absorption capacity of the bolt plates can be economically increased up to 10 times by using suitable polyamide energy absorbers placed between the plate and steel nut parts. It was concluded that the polyamides can be used to remarkably improve the rock bolting performances especially in the rock masses where the high energy absorption capacity property is needed, like those with rock bursting, squeezing and swelling problems.

Quasistatic and low-velocity impact properties of entangled metallic wire material–silicone rubber composites

Entangled metallic wire material–silicone rubber (EMWM–SR) composites with a three-dimensional interpenetrating network structure were manufactured through the vacuum infiltration method with the matrix of entangled metallic wire material (EMWM) and reinforcing element of silicone rubber (SR). Quasistatic compression tests and low-velocity impact tests of the proposed composites were performed, and the deformation model and damage characteristics of the tested EMWM–SR composites were investigated by performing computerized tomography scans and indentation depths. Experimental results show that the stiffness and energy consumption of the EMWM–SR composites are more than twice the sum of those of the individual EMWM and SR in the displacement range of 1.5–4.0 mm. With the increase of loading displacement, the stiffness of EMWM–SR composites increases steadily and the energy consumption increases sharply. Compared with EMWM and SR, the maximum displacement and peak force of the composite materials are decreasing significantly in the low-velocity impact tests. With increasing density, the impact resistance of the composites increases, while the energy absorption decreases. In other words, EMWM–SR 2.6 has better impact resistance but lower energy absorption capacity. The maximum displacement and the peak force increase synchronously with the increase in impact velocity. Interestingly, the composites maintain a high energy absorption capacity at different impact speeds. Furthermore, the energy absorption characteristics of the EMWM–SR composites under low-velocity impact are described in terms of the deformation mechanism of the wires.

Analyzing the influence of the investment casting process parameters on microstructure and mechanical properties of open-pore Al–7Si foams

Aluminum alloy foams with high specific compressive strength and good energy absorption capacity are widely used as structural materials and shock absorbers. The investment casting process offers an interesting opportunity for the production of open-pore aluminum foams. However, foam casting differs from casting of solid parts, and there is a lack of practical knowledge about the microstructure tuning of the ultra-thin cast struts. Our study focuses on the influences of the casting conditions such as mold temperature on the microstructure and consequently on the mechanical properties of aluminum-silicon alloy foams. We investigated microstructural features using various metallography techniques and defined mechanical properties under uniaxial compression test. Here, we observed improvements in the strut microstructure together with decrease of the mold filling by reduction of the mold temperature. Microstructure improvements involve transformation of a single dendritic aluminum grain in each strut to globular grains along with a more homogeneous distribution of the silicon particles across the strut cross-section. These changes bring higher ductility and energy absorption efficiency to the foams, which are evident from the smoother plateau of the stress-strain curves. Decline of the mold filling, on the other hand, has negative effect on the overall mechanical properties.

Energy absorption characteristic and crashworthiness optimization design of VRB-VCS structures under manufacturing constraints

After fully understanding the limitations of traditional variable rolled blank (VRB) and variable cross-sectional (VCS) double-hat shaped beam structures on the energy absorption ability and collision safety optimal design, we propose a variable rolled blank and variable cross-sectional (VRB-VCS) double-hat shaped beam structure with piecewise exponential function. Firstly, the thickness distribution function and the mathematical model of constraint conditions are derived under the constraints of manufacturing rollability. The corresponding finite element (FE) model of the VRB-VCS structure is validated by the dropping hammer impact axial crush experiments, which can predict the crushing process with high fidelity. Secondly, the parametric researches of the energy absorption characteristic of VRB-VCS structure are carried out based on the FE model. The reasonable range of each parameter is obtained by analyzing the influence of the thickness distribution and other key cross-sectional parameters on the energy absorption characteristic and deformation mode of VRB-VCS structure. Finally, the Pareto frontier solutions of the linear and piecewise exponential function VRB-VCS structures are obtained by the multi-objective optimization of the corresponding structures. In comparison to VCS, VRB and linear VRB-VCS structures, the proposed VRB-VCS structure has a higher energy absorption capacity and greater crashworthiness.

Introducing a new hybrid surface strut-based lattice structure with enhanced energy absorption capacity

The present study aims to assess a new lattice structure with high energy absorption capacity. Lattice structures with surface-based unit cell have higher energy absorption than those with strut-based unit cell. A new lattice structure is presented by adding the strut to the surface-based unit cell which has a higher energy absorption capacity than the lattice structures with surface-based unit cell. First, the high energy absorption capacity of surface-based lattice structures was evaluated by adding the strut. Such analyzes are conducted by providing a numerical model which considers the elasto-plasto-damage properties of materials under tension and compression. Then, a number of experimental samples were made using additive manufacturing and the compression test was performed. The results of finite element analysis were consistent with those of the experimental results. Based on the results, adding strut increased the energy absorption for surface-based lattice structures by about 106%. Finally, the effect of the ratio of geometric parameters of the unit cell on its mechanical behavior was evaluated.

High-speed tensile tests on high-manganese steel at low temperatures

Abstract Particularly in the automotive industry and the sector of liquid–gas storage, austenitic steels with a high energy absorption capacity are used. The light metals frequently used do not meet all requirements. Therefore, especially for components involved in crash situations, the cost-effective alternative with outstanding properties is used. In this respect, the high-manganese TWIP steels are of great interest, specifically due to their strength and ductility. Also in other research areas, the high-strength steels are moving into the focus of attention. For example, the properties of welded high-manganese steels at low temperature applications, such as those encountered during storage and transport of liquefied gases, are to be investigated. For this purpose, high-speed tensile tests are used to experimentally determine how the material behaves at different low temperatures and high strain rates. The investigations carried out provide results that can be used to draw conclusions about the strain rate and temperature dependence of the mechanical characteristics. These dependencies are shown as well.

Impact and Blast Resistance of Slurry Infiltrated Fiber Concrete (SIFCON): A Comprehensive Review

The construction field developed Slurry Infiltrated Fiber Concrete (SIFCON) to improve mechanical properties considerably. The durability and ductility of this unique kind of concrete have significantly improved as well, and it has a higher energy absorption capacity. SIFCON differs from other fiber-reinforced concretes because it is produced in a different process, and finally, it contains a significant quantity of fiber, up to 20% or even more. In recent years, several research studies have been conducted on SIFCON, mainly focusing on the performance under impact and blast loading. Although this type of concrete is currently being utilized for significant structures, such as energy plants and military buildings, little is known about how it will respond to blast loads. The aim of this study is to analyze the research findings on enhancing the characteristics and toughness of SIFCON during impact and explosion situations. The review provides essential details about SIFCON that specialists in this field would need to know.

Impact behavior of auxetic structures: Experimental and numerical analysis

Auxetic materials are structured lattice materials with a negative Poisson’s ratio (NPR) and excellent tensile and impact strength compared to conventional bulk materials. It could be used for crashworthy structural applications in aerospace, automotive, and biomedical sections due to its very high specific energy absorption capacity compared to honeycomb structures. With the advent of additive manufacturing technology, it is possible to fabricate complex auxetic structures using metallic, ceramic, and polymeric materials. The literature on the high-speed impact behavior of auxetic structured thermos plastic polylactic acid (PLA) is limited. Therefore, the present work is focused on studying the impact behavior of S-shaped and re-entrant auxetic structures fabricated using Fused Deposition Modeling (FDM). The drop mass impact tests were conducted on these auxetic structures to estimate their impact resistance and energy absorption capability. FEA was undertaken to simulate and validate the impact behavior with experimental results. Quasi-static compression and Split Hopkinson Pressure Bar (SHPB) tests were conducted to get the bulk material's impact properties and material model. These data were used to model material properties in FEA. It was observed that the S-shaped auxetic structure had shown higher compressive plateau stress and energy absorption capacity compared to the re-entrant structure. These auxetic structures' deformation mode and failure were explored through detailed structural analysis using FEA.

Preparation and quasi-static compression properties of hybrid aluminum matrix syntactic foam reinforced with glass cenospheres and silicon carbide nanowires

Conventional hybrid aluminum matrix syntactic foam with various hollow fillers shows low density and high densification strain. However, its peak stress can hardly be increased, resulting in a limited improvement in the energy absorption capacity. Although composites can be reinforced by adding ceramic nanoparticles, it is difficult to achieve dispersion of both hollow and dense fillers in the metal matrix due to their distinct density difference. In this study, we use silicon carbide nanowires reinforced aluminum swarf as the source of ceramic fillers, and prepare hybrid aluminum syntactic foam reinforced by both glass cenospheres and silicon carbide nanowires. The resulting syntactic foam shows low density of 1.3 g cm −3 , high peak stress of 128.6 MPa, and high energy absorption capacity of 60.70 MJ m −3 . Moreover, we demonstrate a novel way to recycle silicon carbide reinforced aluminum composites for reprocessing. • HASF reinforced with a hollow and a dense nanowire filler. • Glass cenospheres and SiCnw forming high dispersion of microscale domains in HASF. • Reprocessing both metal matrix and SiCnw fillers at the same time. • HASF showing strength of 128.6 MPa and energy absorption capacity of 60.70 MJ m −3 .

Fabrication of In-situ Syntactic Aluminium Foam-Filled Steel Tubes

In all areas of industry, when choosing a material, compromises must be made since there is no material with all the properties that are preferential for any use. In the automotive sector, lighter and less dense materials can provide a considerable advantage, for example, lower fuel consumption due to weight reduction. Specialists dealing with materials science within metal foams have been trying to exploit the low density, high specific strength and high energy absorption capacity of metal foams in as many ways as possible for a long time. This research describes the one-step production method of syntactic metal foams with an aluminum matrix infiltrated into a thin-walled steel tube, intended to create functional structures with a strong adhesive bond and metal foam filling in a feasible way.

Axial Compression Study of Crash Boxes with Various Honeycomb Structures

In recent times, automotive manufacturing companies are focusing on developing components that is capable of increasing safety features associated with lightweight materials such as using aluminium. One such innovation is providing the vehicle with crash box, which is generally located at the front bumper. The function of the crash box is to safeguard the passenger by absorbing the kinetic energy of collision and self-deformation. In this paper, the authors presented a study of the compressive test applied on crash boxes with different types of honeycomb sandwich circular columns using 3D virtual modelling and finite element (FE) simulation with the help of Solidworks and Ansys Workbench respectively. This sandwich structure comprises two circular aluminium tubes filled with core shaped as a large-cell honeycomb lattice. Here, the crash boxes with three different honeycomb sandwich circular columns i.e., hexagonal, triangular, and semi-circular arrangement, were investigated and the energy absorption capabilities of these columns were studied. FE simulations were used to evaluate maximum stress that a material can sustain over a period under a load, material deformation, geometric changes, and load-displacement results using a constant material property of that of aluminium alloy, and the results of the three different arrangements were compared and it is known that the crash box with semi-circular arrangement has high energy absorbing capacity.

Comparative and parametric study of aluminium honeycomb sandwich composites and GRP

Sandwich composites are a special class of material because of distinctive properties such as lightweight, high damping and high energy absorbing capacity, which in turn make this material highly suitable for the shipbuilding industry. The traditionally used materials for hull construction in the shipbuilding industry are steel, Glass Reinforced Plastic (GRP) and wood which is prone to problems such as weight and strength reduction due to water absorption over a period of time. This manuscript presents a comparative study of specific energy absorption (SEA) of GRP sheets and two different aluminium honeycomb sandwich composites one of which has aluminium honeycomb core and aluminium face sheet/skin and the other has aluminium honeycomb core and GRP face sheet. Experiments are carried out on the GRP sheet and sandwich composite with aluminium honeycomb core and aluminium as face sheet using Charpy ASTM E-23 machine. The experimental results are compared with the numerical results obtained from Abaqus and are found to be in good agreement. Further, the numerical simulation has been carried out on sandwich composites and GRP sheets varying several parameters such as foil thickness of honeycomb in sandwich composites, and skin of sandwich composites (aluminium sheet and GRP). Failures have been discussed based on stress theories and the deformation patterns of sandwich composites and GRP sheets (obtained from the numerical and experimental investigation) have been compared. The maximum impulse force has also been presented by using the impulse-momentum equation. It has been found in the study that the aluminium honeycomb sandwich composites with aluminium as face sheet possess high energy absorption to mass ratio than the pure GRP sheets and the aluminium honeycomb sandwich composites with GRP sheet as skin. Further parametric study reveals that the energy absorption to mass ratio increases with increase in foil thickness in both type of honeycomb sandwich composites.

Effect of plastic strips on elastic properties of concrete under cyclic loading

Heterogeneous characteristics of concrete with variation in strength of matrix, aggregate and interface causes non-uniform distribution in stress. Reinforcing concrete alters this distribution and can be designed to reduce non-uniformity. Present study investigates applicability of plastic strips as reinforcement to improve performance of concrete. Since plastic strips are strong in tension, they are oriented to control tensile stress generated in concrete. The approach adopted contributed to increment in compressive strength of fibre reinforced concrete. In comparison with conventional concrete, fibre reinforced concrete has higher but delayed compressive strength, lower initial stiffness and higher energy absorption capacity. In order to assess impact of plastic strips on fundamental properties like Young’s modulus and poisons ratio, cylindrical samples with radially oriented plastic strips are subjected to cyclic loading. Poisson’s ratio is computed by measuring axial and lateral deformation in the sample. To compute Young’s modulus, axial deformation is measured along the gauge length. Response of conventional and fibre reinforced concrete is measured for both loading and unloading cycles considered. In comparison with conventional concrete, fibre reinforced concrete reflects higher axial deformation but the lateral deformation is restrained. This contributes to lower Poisson’s ratio for fibre reinforced concrete. Reduction in lateral deformation of fibre reinforced concrete is an effect of confinement generated by plastic strips. The presence of confinement effect reduces net stress acting at a material point thus increasing compression capacity of concrete. Further, Young’s modulus of fibre reinforced concrete decreases in comparison with conventional concrete. This is due to softening effect of plastic strips in axial direction. However, progressive increment in loading causes substantial degradation in young’s modulus of conventional concrete whereas for fibre reinforced concrete it remains largely stable. Similar stability in also response is reported for poisons ratio. The present study thus establishes role of plastic strips in developing confinement effect contributing to improved performance and predictability in response of strength and material parameters namely Young’s modulus and poisons ratio.

Study on crashworthiness of nature-inspired functionally graded lattice metamaterials for bridge pier protection against ship collision

Lightweight lattice metamaterials can effectively enhance the impact resistance of thin-walled structures. With the aim of further investigating the potential of lattice-filled composite structures, an innovative nature-inspired functionally graded lattice filled protection structure (FGLPS) is proposed in this paper to enhance structural energy absorption characteristics under ship impact loadings. At this point, two different graded patterns (i.e. increasing graded pattern and decreasing graded pattern with partition design) for lattice metamaterial fillers are established, then the effects of gradient model and impact angle on energy absorption characteristics of lattice-filled structures are studied using ship impact finite element model with multiple collision conditions. The results show that the novel functionally graded lattice filled thin-walled structure can significantly reduce the peck impact force, prolong the impact time and play prominent protective role. Especially, the peak impact force generated during the vessel impact on bridge pier can be reduced by up to 60.01% through zonal gradient design. Besides, FGPLS can absorb up to 33.15% of total impact energy by plastic deformation, and both increasing and decreasing gradient structure have the potential ability to significantly reduce the impact damage. The findings of this study provide a new approach to the engineering applications of collision-resistant structures with high energy absorption capacity.

Improved energy absorption capacity of Al/Al2O3 foams by the ductile/brittle hybrid deformation mode

In the present study, Al/Al 2 O 3 foams were prepared to increase the energy absorption capacity by enlarging the densification strain. Analysis of the mechanical characteristics was performed and the energy absorption ability was calculated on the samples. The deformation process of the inner and outer-layer cells was investigated on the micro- and macro-scales to clarify the optimisation mechanism of the densification strain. The stress–strain curves demonstrated that the ceramic/aluminium foam exhibited an extended plateau region (densification strain of 0.63), resulting in high energy absorption capacity and efficiency. Analysis of the deformation process illustrated that the oxide layer played a dominant role in the brittle deformation of the outer-layer cells. The evolution of crack formation, propagation, and coalescence in cells provided randomly distributed “defects” in foams, resulted in the scattered plastic deformation zones in inner cells. The strain hardening effect of the cell wall was suppressed based on this typical deformation mode of foam, which resulted in increased densification strain and improved energy absorption capacity. Moreover, the Al/Al 2 O 3 foams exhibited superior corrosion resistance compared to the Al foams.

Experimental and numerical study on ballistic resistance of aluminum foam sandwich panel considering porosity and dimensional effect

Sandwich panels have been widely used in various industries due to their high strength and energy absorption capacity. In this study, the ballistic behavior of a sandwich panel comprised of two aluminum face-sheets and an aluminum foam as the sandwich core is studied. The panels are constructed and subjected to the blunt-nosed projectile. The experimental test consists of a sandwich panel with three different ranges of foam densities and two thicknesses for the panels beside hardened steel projectiles. Then, numerical simulations of the projectile perforation in the panels are conducted that are in good agreement with the experiments. The failure mechanism of the sandwich panels is investigated and the role of foam core is discussed. Failure mechanism and the amount of plug depends on foam density and projectile velocity, such that different failure mechanisms such as plugging, petaling, and dishing occurred for the face-sheets. After that, the ballistic limit velocity (VBL) of sandwich panels was calculated via experiments and finite element simulations. The experiments and simulations showed that increasing the density and thickness of the foam core generally leads to an increase in VBL. Finally, we study the panels with the constant mass and (or) constant height with different foam densities and the effect of foam density is investigated in these cases.

Damage assessment of stiffened steel plate shear walls with different configurations under far-fault and near-fault ground motions

Preventing damages and reducing the consequences of natural disasters such as earthquakes are nowadays considered as the most important considerations in improving the existing structures or designing new ones. A steel plate shear wall (SPSW) is one of the systems that resist lateral loads. Despite its significant benefits such as load capacity, plasticity, and high energy absorption capacity, the SPSW has a serious weakness: early buckling of infill plates under lateral loads. To solve this problem, some stiffeners with various distributions and geometries are used in the SPSWs. Adding these stiffeners brings about some changes in the seismic behavior (such as the seismic damages) of the structure. Therefore, in this study, we investigated the effects of various configurations of stiffeners in the shear walls on the damage level of the structures (5, 10, 15, and 20 floors) under earthquake excitations. The shear walls are either with openings (due to their implementation aspects and easy application) or without openings. Thirty-three earthquake excitations were applied (both far-field and near-field earthquakes) on the structures. Also, a non-linear dynamic analysis was performed to calculate the damages according to the three damage indexes of Park-Ang, Iemura-Mikami, and relative displacement. First, the structures were designed and modeled by the finite element software. Then, according to the definition of damage indices, the damage and performance level of the structures under earthquake records were studied and evaluated. The obtained results were presented in two separate parts. In the first part, due to the importance of model verification, the results of the study were compared with the results of the experimental models of the SPSWs with different stiffener configurations. In the second part, the effects of various configurations of stiffeners on damage indices of the SPSW with and without openings were evaluated. Based on the obtained results, the configurations of steel shear walls including the distribution of stiffeners and openings were found to have a significant effect on the amount of damage caused by seismic excitations. This effect depends on various factors for which the details are presented in this study.

Energy-Absorbing and Eco-Friendly Perspectives for Cork and WKSF Based Composites under Drop-Weight Impact Machine

Lightweight structures with high energy absorption capacity are in high demand for energy absorption applications in a variety of engineering fields, such as aerospace, automotive, and marine engineering. Anti-impact composites are made of energy-absorbing materials that are incorporated into structures to protect the occupant or sensitive components against strikes or falls. This study deals with an experimental investigation of multi-layer composites consisting of cork and warp-knitted spacer fabrics (WKSF) for anti-impact applications. Composites were designed and created with a laser cutting machine in eight different configurations. To measure the energy absorption of the manufactured composite samples, a low-velocity drop-tower machine was designed, and the maximum reaction force due to the strike of the impactor on the specimens was measured by a dynamometer located under the samples. Moreover, energy absorption and specific energy absorption capacities were calculated for each specimen. In the final part of this study, the Life Cycle Assessment (LCA) of the designed composites was calculated to understand the eco-friendly properties of the composites.

Liquid metal lattice materials with simultaneously high strength and reusable energy absorption

It is imperative to develop lattice materials with reusable energy absorption for sustainable, economic, and environmental considerations. Unfortunately, existing reusable lattice materials do not usually have both high strength and high energy absorption capacity simultaneously. To overcome this challenge, we developed four types of liquid metal lattice materials and explored their mechanical and recovery behaviors in this work. These beam and shell lattice materials have a liquid metal lattice core coated with two polymer coatings. It is found that the new hybrid coating is stronger and more durable compared to silicone coating alone. The Kelvin beam lattice and Primitive shell lattice are among the best candidates as reusable liquid metal lattice materials. By comparing various reusable lattice materials in the literature, it is found that the liquid metal lattice materials have the highest strength and energy absorption capacity due to the intrinsic metallic features.