Impact Energy Absorption Characteristics Research Articles

Impact resistance and energy absorption characteristics of nickel-based alloy ring at elevated temperatures

To evaluate the high-temperature containment capability of a turbine casing, the impact resistance of half-ring specimens and full circular casings made of GH4169 nickel-based alloy was investigated. Ballistic impact tests were first conducted on GH4169 half-ring specimens using blade-shaped projectiles of DZ125 material fired from a single-stage gas gun. Meanwhile, explicit finite element simulations of the half-ring impact tests were performed with LS-DYNA. Comparing experimental and simulation results validated the accuracy of the model and revealed the effects of impact angle and ambient temperature. Then the process of a turbine casing containing a blade at 500 °C was simulated using the validated FE model. The results showed that the impact angle and the ambient temperature significantly affect the impact resistance of GH4169 half-ring specimen. Furthermore, the interaction mechanism between the turbine blade and casing differs across the three stages of the containment process.

Experimental and numerical study of drop hammer test on honeycomb sandwich panel resistant to rock burst in coal mine roadway

This study addresses the ubiquitous issue of effective support resistant to the rock bursts within coal mine roadways and introduces an innovative solution in the form of a steel honeycomb sandwich panel (HSP). It is designed for installation on traditional metal supports in coal mine roadways, serves as an integral element of an energy-absorption support system tailored to withstand rock burst impacts. The investigation incorporates drop hammer impact tests conducted on eight HSP specimens, varying in cell wall thickness and core height. A comprehensive three-dimensional finite element model, inclusive of mesh considerations, was constructed and subsequently validated. Combining experimental and numerical approaches, the drop hammer impact response and energy absorption characteristics of HSP structures were analyzed. The findings reveal good energy absorption capabilities, with HSPs dissipating over 90 % of impact energy, over 85 % attributed to the core layer. Thinner core cell walls reduce peak impact loads, mitigating structural impact effects. In the experimental parameters delineated in the present study, it is observed that core layers with thicknesses of 1.0 mm and 1.5 mm demonstrate enhanced energy absorption capabilities. Variations in core height minimally affect peak impact forces, with only a 7.41 % distinction between 60 mm and 140 mm core layers. However, it is worth noting that higher core layers can achieve an enhanced energy absorption capacity. Thinner facesheets enhance energy absorption, and alterations in impactor mass have minimal effects under constant impact energy conditions. Additionally, a predictive equation for estimating indentation depth was proposed, closely aligned with finite element results. This equation holds potential for informing future HSP designs, offering valuable insights for diverse engineering applications.

Ultra-High-Performance Concrete (UHPC): A state-of-the-art review of material behavior, structural applications and future

Ultra-high-performance concrete commonly known as UHPC is rising curiosity among structural engineers all over. Though early research on this material dates back to a couple of decades, some initial knowledge about this material, its behavior, and its properties is largely limited to a few research circles in a handful of advanced countries. This paper introduces UHPC as a material, elaborates on its ingredients, and describes its properties. A detailed review of available research literature about UHPC is made. The contributions made by several researchers have been discussed in detail. Following this, the structural behavior and strength of the material are reviewed comprehensively. Comparisons are made between conventional concrete and UHPC with respect to their properties, stress-strain relation, cracking behavior, compressive, tensile, and shear strengths. A detailed evaluation is made of the enhanced properties of the material with respect to its durability and long-term performance. The resistance of this material to moisture permeability, chloride ingress, and chemical attacks is understood. The impact resistance and energy absorption characteristics of the material are compared with conventional concrete. The study documented the structural applications of UHPC as well as the potential applications in the field of civil engineering. Finally, the authors enlisted the impacts of this new material (UHPC) on the future direction of structural engineering and the innovative solutions it can provide to structural engineering problems

Impact Resistance and Energy Absorption Characteristics of the Bionic Turtle Shell Structure

The microstructure of the shell is a kind of “sandwich” structure with a denser outer layer and a less dense inner layer, density, which can be identified as a functional gradient material in engineering. It has excellent performance, such as earthquake resistance and shock resistance. In order to study the reliability of this kind of material, a kind of shell structure is designed in this paper. In the range of elastic deformation constraints of the material, simulate and calculate bionic structure the bionic structure. Firstly, a three-point bending analysis is carried out to investigate the mechanical properties of the bionic structure under a bending load. Secondly, through the Finite Element Analysis, the mechanical properties of the shell structure and the general structure under the same load are analyzed and compared. The simulation results show that in the three-point bending analysis, the maximum equivalent stress of the simulated shell structure under impact load is reduced by 1.4 times compared with the general structure. The energy absorption analysis showed a 1.6-fold increase.

A novel design method of circular sandwich panels with gradient continuous controllable core based on space-filling design and 2D-Voronoi method

In this paper, a novel method based on the space-filling design and 2D Voronoi method was proposed to design the in-plane gradient continuous controllable honeycomb (GCCH) structures. Low-velocity impact tests were carried out using the sandwich panels with GCCH core layers, which were all made of Aluminium alloy material and fabricated with the wire-cut machine. A concise theoretical solution for loading capacity and denting profile was developed and verified. Three-dimensional finite element models were implemented in ABAQUS/Explicit to model sandwich panels.The FE models were validated with experimental results and, subsequently, the simulation results were further extended to study the impact response and energy absorption characteristics. Results show that the method proposed in this work was effective to design multi-cell structures with graded mechanical properties in the radius direction and approximately homogeneous in the circumferential direction by controlling the distribution of the sites. Sandwich panels with GCCH core layers had better energy absorption properties compared with sandwich panels whose core layers were hexagonal honeycomb with similar cell wall lengths.

Effect of impactor velocity on low velocity impact behavior of Al/SiC monocoque interpenetrating composites

This study investigates the impact behavior and energy absorption characteristics of C4 composites under different initial energy conditions. The force-displacement responses were recorded using a conical impactor on an impact testing machine. Three configurations of C4 composites with varying pore sizes (10PPI, 20PPI, and 30PPI) were tested at three initial impact energies (208 J, 312 J, and 416 J). The force-displacement curves revealed that the 30PPI-C4 exhibited the highest force gradient and maximum force, followed by the 20PPI-C4 and 10PPI-C4. The maximum force increased with increasing impact energy for all configurations. Velocity attenuation during impact tests showed a correlation with deformation and collapse mechanisms of the C4 composite. Energy absorption analysis indicated that the 30PPI-C4 exhibited the highest energy absorption per unit mass, followed by the 20PPI-C4 and 10PPI-C4. Visual inspection revealed circular indentations and shear cracks on the top and bottom surfaces, with increasing damage area and depth of indentation at higher impact energies. The 30PPI-C4 demonstrated better resistance to indentation and failure, along with higher specific energy absorption. The refined grains in the 30PPI-C4 contributed to crack mitigation and energy absorption. The C4 composites with higher SiC volume percentages exhibited reduced damage area and higher stability during impact tests. The study concludes that the 30PPI-C4 composite with 18 vol% SiC foam shows superior impact resistance and energy absorption properties, making it a promising material for impact-related applications.

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.

Experimental and Numerical Studies on the Impact Energy Absorption of Cutting Shear Rings

To improve the passive safety of the collision process, we designed a kind of energy absorption device based on cutting shear rings (CSR). It can be installed in a limited space, overcoming the characteristic of traditional energy absorption devices that cannot play their advantages in a narrow space, and it will not be accompanied by the splashing of chips in the process of energy absorption. The impact energy absorption characteristics of the shear rings outside the energy absorption rods are analyzed. The feasibility of the finite element method to study the device’s characteristics is demonstrated through the combination of the drop hammer test and numerical simulation. At the same time, the device’s responses under nine different working cases are simulated, and the impact energy absorption characteristics of the shear rings are analyzed. Moreover, the effects of shear ring thickness and spacing on the device are also analyzed. The results show that there are several peak forces during the energy absorption process, and each peak force is accompanied by the failure of the shear ring. The shear rings’ thickness correlates positively with energy absorption and peak force. But the spacing of shear rings only affects the number of peak forces. There is a linear trend between the shear rings’ spacing and energy absorption, and the slope of the trend increases with the increase in thickness.

Bionic design and multi-objective optimization of thin-walled structures inspired by conchs

<abstract> <p>Thin-walled structures have been widely used in various parts of vehicle subsystems because of their high-efficiency impact energy absorption and lightweight characteristics. However, the impact deformation mode of conventional thin-walled structures is unstable and the energy absorption efficiency is low. Therefore, a series of novel bionic conch structures (BCS) are proposed to find a more excellent crashworthiness design in this study. First, the finite element simulation model of BCS verified by experiments is established. Then, the energy absorption characteristics of bionic conch structures, and conventional single-cell and multi-cell tubes under axial loading are compared by employing finite element simulation. The results show that the thin-walled structures inspired by conchs have a higher energy absorption efficiency than the other two structures with the same mass. In addition, the influence of main design parameters (wall thickness, inner and outer ring diameter, and the number of inner and outer panels) on the crashworthiness of BCS is studied through parameter design and factor significance analysis. Finally, the optimal geometric configuration is found by combining the approximation model and multi-objective particle swarm optimization, and the crashworthiness of BCS is further optimized. The bionic crashworthiness design and optimization framework proposed in this study can also provide a reference for other engineering protective structures.</p> </abstract>

Deformation Behaviour and Mechanical Response of Closed-cell Cellular Materials under Projectile Impact Using Various Shapes Impactors

Closed-cell cellular materials gained tremendous interest in their application in aerospace, shipbuilding and defence industries due to their exceptional impact energy absorption and lightweight characteristics. To assess the suitability of these materials in practical utilisation, a proper characterisation in dynamic loading is necessary. This paper investigates closed-cell aluminium foam's deformation behaviour due to low-velocity projectile impact in experimentation and finite element analysis. The collapse mechanism was numerically and empirically examined. The experiment and the finite element analysis were found to be in good agreement. The low-velocity projectile impact tests were conducted using an instrumented drop-tower with several projectile tips with an impact energy of 105 J. Finite Element modelling using ABAQUS explicit was undertaken. The results reveal that FE modelling of true foam properties using solid geometry has a good correlation with experimental results. In this study, four impactors/indenters (flat-faced, hemispheric, conical, and truncated-conical) were used. A detailed structural collapse during the low-velocity dynamic impact has been explored with XCT data and finite element tools.

Influence of Defects on In-Plane Dynamic Properties of Hexagonal Ligament Chiral Structures

Although the six-ligament chiral structure has many unique properties, due to its special structure, the stress concentration is prone to defects. In addition, additive manufacturing is also prone to defects. This paper studies the effect of defects, which is helpful for the better application of the six-ligament chiral structure. Several new six-ligament chiral structures with random and concentrated defects were designed to explore the effects of the defects on the in-plane dynamic properties. The structures were studied with the finite element ANSYS/LSDYNA numerical simulation and experimental methods. According to the defect-free six-ligament chiral structures exhibiting different deformation modes at different impact velocities, the effects of the defect rate and type (concentrated and random defects) on the six-ligament chiral structure, the in-plane impact deformation mode and energy absorption characteristics are discussed. The research results show that the defect rate and type reduce the energy absorption characteristics of the chiral structure to varying degrees, and the impact deformation mode also changes under medium- and low-speed impact. With the increase in speed, the influence of the defects on the deformation mode weakens. Moreover, the effects of the concentrated and random defects on the platform stress are different. When the defect rate is low, the effect of the random defects is more significant, and as the defect rate increases, the effect of the concentrated defects is more obvious. The study can provide guidance for structural design, predict the failure form of structures containing defects when they are impacted, and realize material recycling.

Impact energy absorption of block copolymer/tackifier blends: Effect of compatibility, viscoelasticity, and laminate structures

AbstractThis work studied the effects of tackifiers on the impact energy absorption properties of block copolymers (BCPs) comprising poly(styrene)‐b‐poly(isoprene)‐b‐poly(styrene) (SIS) and poly(methyl methacrylate)‐b‐poly(n‐butyl acrylate)‐b‐poly(methyl methacrylate) (MAM). A rosin ester resin (RE) and an aliphatic petroleum resin (C5PR) were compared as the tackifiers. Analyses of Hansen solubility parameters and observations using electron microscopy indicated that both tackifiers were highly compatible with the poly(isoprene) component of the SIS, while the RE also showed good compatibility with the poly(n‐butyl acrylate) phase of the MAM. The impact energy absorption characteristics of laminates made by applying layers of BCP/tackifier blends to cured epoxy substrates were evaluated using a pendulum impactor. The extent of energy absorption by these laminates was found to increase within specific tackifier concentration ranges. However, the C5PR showed poor compatibility with the MAM and had almost no effect on the energy absorption of the laminates. The energy absorption of the laminates could be described based on the calculated loss factor,η, determined using the RUK equation including the viscoelastic parameters (both tanδand storage modulus) for the BCP/tackifier blends, considering the time–temperature superposition principle, and for the laminate structures.

Influence of geometry constraint in finite space on impact resistance of shear thickening fluid

The shear thickening area formed by impact load and the restriction boundary conditions play an important role in the impact resistance and energy absorption characteristics of the shear thickening fluid (STF). In order to reveal the low speed impact resistance of STF under finite space constraints, this paper carried out research through the preparation of STF, viscosity test and design of low speed drop weight impact experiment. Firstly, STF samples with different mass fractions were prepared by self-made. Then, the rheological tests were implemented to obtain the characteristics of STF viscosity under different shear rate loads. Next, a straightforward test through rapidly pulling the glass rod out of the STF was adopted to observe the shear thickening mechanism of STF. After that, two kinds of STF samples with different mass fractions and good shear thickening performance were selected for low speed drop weight test. In the drop weight test, three containers with different geometries were designed to equivalent the finite space constraints to reveal the low speed impact resistance of STF under finite space constraints. Finally, combined with the experimental results, a series of numerical models are established to study the influence of geometric parameters in finite space on the impact resistance of STF. Through the research of this paper, the influence of geometry constraint in finite space on impact resistance of STF was obtained, which can provide reference for the geometric design of protective structure filled with STF.

Evaluation of concrete bricks with crumb rubber and polypropylene fibres under impact loading

The influence of Polypropylene (PP) fibres and crumb rubber (CR) on the concrete bricks under impact loading was studied through experimental as well as statistical analysis. A total number of 12 mixes were considered with different percentages of only PP fibres as phase 1, crumb rubber with fibres as phase 2 and only crumb rubber as phase 3, at 28 days. In phase 1 of Mixes 1–4, the PP fibres were added into control mix (CM) with varying percentage of volume fraction, i.e., 0.1%, 0.2%, 0.3%. The highest strength to weight ratio found for the mix 3 (0.3% PP fibres), however PP fibres at 0.2% were considered as best in terms of preparation of the mixes. In phase 2 of Mixes 5–8, the crumb rubber was replaced by 3, 6, 9, and 12% by volume of fine aggregates of size less than 4.5 mm along with 0.2% PP fibres. In phase 3 of Mixes 9–12, fine aggregates were replaced by crumb rubber by 3, 6, 9, and 12% without fibres to explicitly perceive the influence of fibres on crumb rubber concrete. The durability tests of the bricks such as Initial rate of water absorption (IRWA) and water absorption was performed all chosen mixes however, efflorescence and sulphate attack tests were carried out on mix 5–8. The mechanical strength of bricks under compression, tension and flexure was determined. Further, impact energy absorption characteristics studies/tests were carried on Mix 1 and Mix 5–12 using drop weight impact tests. It was observed that the addition of crumb rubber of 12% along with 0.2% of PP fibre (Mix 8) reduced the density by 9.41% compared to the control mix (Mix 1). It was also observed that the energy absorption capacity was found to increase with an increase of CR up to 6% along with 0.2% PP fibre, whereas increasing replacement level beyond 6% CR, the impact energy absorption capacity found decreased. It was concluded that the reliability life assessment of brick made using crumb rubber and fibre can be predicted using two-parameter Weibull distribution.

Compression Behavior and Impact Energy Absorption Characteristics of 3D Printed Polymer Lattices and Their Hybrid Sandwich Structures

Compression Behavior and Impact Energy Absorption Characteristics of 3D Printed Polymer Lattices and Their Hybrid Sandwich Structures

Enhanced impact energy absorption and failure characteristics of novel fully thermoplastic and hybrid composite bicycle helmet shells

Current research realize to develop a safer, lighter and higher energy absorbing fully thermoplastic (polypropylene fibres and acrylic Elium resin) and hybrid composite helmets (polypropylene/carbon hybrid and Elium resin) and perform the CPSC 1203 certification tests on different anvils. The failure and energy absorption mechanisms were studied and compared with widely used polycarbonate helmets (PC/EPS) and the composite shells manufactured with epoxy resin. The fully thermoplastic and hybrid composite shells have shown up to 65% of absorbed energy while the polycarbonate shells have absorbed a maximum of 13% of the absorbed energy. The usage of composite shells has lead to minimal energy transfer to the foam which is directly attached to the human head and provided improved safety. The high-speed camera has shown clear deformation of the thermoplastic composite shell owing to the ductile behaviour while the catastrophic failure with significant cracks was observed in the Epoxy-based composite shell. Considering the head injury criteria, the PC/EPS helmet showed the highest fatality rate (6%) when impacted on the flat anvil. The usage of fully thermoplastic and hybrid composite shell reduces the probability of critical and fatal injury by around 40% and 60% respectively when compared to PC/EPS configuration.

Impact resistance of steel materials to ballistic ejecta and shelter development using steel deck plates

The destruction caused by ballistic ejecta from the phreatic eruptions of Mt. Ontake in 2014 and Mt. Kusatsu-Shirane (Mt. Moto-Shirane) in 2018 in Japan, which resulted in numerous casualties, highlighted the need for better evacuation facilities. In response, some mountain huts were reinforced with aramid fabric to convert them into shelters. However, a number of decisions must be made when working to increase the number of shelters, which depend on the location where they are to be built. In this study, we propose a method of using high-strength steel to reinforce wooden buildings for use as shelters. More specifically, assuming that ballistic ejecta has an impact energy of 9 kJ or more, as in previous studies, we developed a method that utilizes SUS304 and SS400 unprocessed steel plates based on existing impact test data. We found that SUS304 is particularly suitable for use as a reinforcing material because it has excellent impact energy absorption characteristics due to its high ductility as well as excellent corrosion resistance. With the aim of increasing the structural strength of steel shelters, we also conducted an impact test on a shelter fabricated from SS400 deck plates (i.e., steel with improved flexural strength provided by work-hardened trapezoidal corrugated plates). The results show that the shelter could withstand impact with an energy of 13.5 kJ (2.66 kg of simulated ballistic ejecta at 101 m/s on impact). In addition, from the result of the impact test using the roof-simulating structure, it was confirmed the impact absorption energy is further increased when artificial pumice as an additional protective layer is installed on this structure. Observations of the shelter after the impact test show that there is still some allowance for deformation caused by projectile impact, which means that the proposed steel shelter holds promise, not only structurally, but also from the aspects of transportation and assembly. Hence, the usefulness of shelters that use steel was shown experimentally. However, shelter construction should be suitable for the target environment.

Effect of Molding Temperature and Thickness on Impact Energy Absorption Characteristics of Thermosetting CFRP Pipes

Effect of Molding Temperature and Thickness on Impact Energy Absorption Characteristics of Thermosetting CFRP Pipes

The impact energy absorption characteristics of the double structure filled with foam material

The impact energy absorption characteristics of the double structure filled with foam material

The impact behavior of the crash boxes

This article will study the impact behavior of the crash box structures. The crash boxes are found between the front cross member and the front side members. They play an important role in case of minor frontal impact, speeds up to 15km/h. For this study, we propose three models of crash boxes of different sections. The impact analysis will be performed using the software ANSYS, Explicit Dynamics module. The shape and dimensions of the models were obtained from repeated impact tests. Thus, the obtained results were used for the continuous improvement of the crash boxes. The proposed models are made from extruded Aluminum bars with different sections. With the help of finite element analysis (FEM) one can compare the results and what impact energy absorption characteristics each proposed model of structure presents.