High Energy Absorption Capacity Research Articles

Investigation of the bending and crushing for the light-weight structures used in vehicle's radiator

Sandwich panels are widely used in various industries, including the aerospace industry, where they have long been regarded because of their light-weight and high energy absorption capacity. This research introduces a novel type of sandwich panel whose raw material is widely used in the automotive industry. The materials used for manufacturing the sandwich panels addressed in this research are currently used in the cooling radiator structure for the engine of conventional vehicles. Such a radiator is nothing but a lattice of a set of B-shaped tubes and cooling fins. In this research, the crashworthiness properties of such a lattice are extracted along with various directions (samples A, B, and C). Moreover, the applicability of the considered lattices as the core of sandwich panels was studied. This research showed that the considered structures tend to exhibit maximum strength when the loading plane is parallel to the cooling fins. It was further figured out that the addition of aluminum shells to specimens A, B, and C can increase their energy absorption capacity by 85, 268, and 13%, respectively.

Energy absorption characteristics of functionally graded polymer-based lattice structures filled aluminum tubes under transverse impact loading

This paper aims to evaluate the potential use of an innovative functionally graded lattice-filled composite beam composed of axial and radial graded three-dimensional lattice cores. Graded lattice filled circular beams with different graded patterns are compared with homogenous lattice filled counterparts. Graded lattice core samples are prepared using 3D printing techniques, inserted into thin-walled tubes and subjected to three-point bending loads. Then numerical models are created in Abaqus and verified against the experiments. Parametric studies find that the novel lattice-filled structure absorbs more energy but yields larger crushing force than the uniform counterpart. In addition, various parameters, like gradient parameter and filling length, thickness and yield stress of column wall, have a considerable impact on the crashworthiness of this novel structure. Finally, multi-objective optimization is performed to maximize specific energy absorption while reducing maximum impact force. Optimization results show that graded lattice-filled structures produce superior Pareto solutions than the ordinary counterparts. Especially, the specific energy absorption can be increased to 173.9% and increasing graded lattice-filled structure has the best crashworthiness, and the least decreasing graded lattice-filled structure. The functionally graded lattice core of this study provides a novel approach to design new crash-resistant energy absorber with high energy absorption capacity.

EFFECT OF STRENGTH OF FILLED-CONCRETE ON STRUCTURAL PERFORMANCE OF CONTINUOUS BEAM-TYPE SQUARE CFST BEAM-TO-COLUMN CONNECTION

Continuous beam-type concrete-filled steel tube (CFST) column connections are simple to fabricate and exhibit effective seismic performance. Fujinaga and Clifton have previously studied the performance of continuous beam-type square CFST beam-to-column connections using concrete of relatively high strength (85 MPa) and demonstrated their effective performance and high energy-absorbing capacity. However, in their study, it was found that the local deformation of the steel beam under bending-induced beam tension had a large effect on the steel tube flange near the connection. Further, it was observed that filled concrete may not contribute substantially to the transmission of compressive load at the connection panel if low-strength concrete is used. In this study, the square CFST beam-to-column connection was investigated, and the connection performance and load transfer mechanisms were examined when the strength of the concrete was relatively low (40 MPa). The specimens demonstrated effective seismic performance, exhibiting sufficient strength and stable hysteretic behavior with high energy absorption even when low-strength concrete was used. Irrespective of the strength of the concrete used, the strain developed in the steel tube flanges was low on the compression side, and the filled concrete contributed to the transmission of the compressive load at the connection panel. The compressive strain in the steel tube was slightly higher when the strength of the concrete was low.

Dynamic crushing behavior of closed-cell aluminum foams based on different space-filling unit cells

Closed-cell metal foams are cellular solids that show unique properties such as high strength to weight ratio, high energy absorption capacity, and low thermal conductivity. Due to being computation and cost effective, modeling the behavior of closed-cell foams using regular unit cells has attracted a lot of attention in this regard. Recent developments in additive manufacturing techniques which have made the production of rationally designed porous structures feasible has also contributed to recent increasing interest in studying the mechanical behavior of regular lattice structures. In this study, five different topologies namely Kelvin, Weaire–Phelan, rhombicuboctahedron, octahedral, and truncated cube are considered for constructing lattice structures. The effects of foam density and impact velocity on the stress–strain curves, first peak stress, and energy absorption capacity are investigated. The results showed that unit cell topology has a very significant effect on the stiffness, first peak stress, failure mode, and energy absorption capacity. Among all the unit cell types, the Kelvin unit cell demonstrated the most similar behavior to experimental test results. The Weaire–Phelan unit cell, while showing promising results in low and medium densities, demonstrated unstable behavior at high impact velocity. The lattice structures with high fractions of vertical walls (truncated cube and rhombicuboctahedron) showed higher stiffness and first peak stress values as compared to lattice structures with high ratio of oblique walls (Weaire–Phelan and Kelvin). However, as for the energy absorption capacity, other factors were important. The lattice structures with high cell wall surface area had higher energy absorption capacities as compared to lattice structures with low surface area. The results of this study are not only beneficial in determining the proper unit cell type in numerical modeling of dynamic behavior of closed-cell foams, but they are also advantageous in studying the dynamic behavior of additively manufactured lattice structures with different topologies.

Hybrid Polymer Composites Used in the Arms Industry: A Review.

Polymer fiber composites are increasingly being used in many industries, including the defense industry. However, for protective applications, in addition to high specific strength and stiffness, polymer composites are also required to have a high energy absorption capacity. To improve the performance of fiber-reinforced composites, many researchers have modified them using multiple methods, such as the introduction of nanofillers into the polymer matrix, the modification of fibers with nanofillers, the impregnation of fabrics using a shear thickening fluid (STF) or a shear thickening gel (STG), or a combination of these techniques. In addition, the physical structures of composites have been modified through reinforcement hybridization; the appropriate design of roving, weave, and cross-orientation of fabric layers; and the development of 3D structures. This review focuses on the effects of modifying composites on their impact energy absorption capacity and other mechanical properties. It highlights the technologies used and their effectiveness for the three main fiber types: glass, carbon, and aramid. In addition, basic design considerations related to fabric selection and orientation are indicated. Evaluation of the literature data showed that the highest energy absorption capacities are obtained by using an STF or STG and an appropriate fiber reinforcement structure, while modifications using nanomaterials allow other strength parameters to be improved, such as flexural strength, tensile strength, or shear strength.

Energy Absorption Capacity of Concrete-Filled Steel Tube Slender Columns with Different Aspect Ratios

The present paper examines the energy absorption capacity of concrete-filled steel tube slender (CFTS) columns having different aspect ratios. The CFTS columns are nonlinearly analysed employing the finite element software ABAQUS. In order to validate the simulation of the columns, an experimentally tested CFTS column is simulated and its achieved result is compared with that of the tested column. Since it is concluded that there is a good agreement between the obtained results from the simulation and experimental test, the validation of the simulation is then established. The simulated columns are thereafter developed using different aspect ratios of 6, 10, and 13 and also considering the following parameters: load eccentricities, cross-sectional shapes, and steel tube thicknesses. The columns are nonlinearly analysed and the results are achieved from the analyses. The effects of the above-mentioned parameters on the energy absorption capacity of the CFTS columns are evaluated. From the results, it can be concluded that the energy absorption capacity of the columns is decreased by the increase of the load eccentricity or aspect ratio. Further, the energy absorption capacity of the circular CFTS column is greater than that of the rectangular and square CFTS columns. However, higher energy absorption capacity is accomplished for the rectangular column than the square column. Additionally, increasing the steel tube thickness leads to greater energy absorption capacity of the columns. Typical failure modes of the columns are assessed.

Lightweight and dual-functional composites with stiff-soft microstructure for energy absorption and thermal insulation

Lightweight composite materials with high energy absorption performance can find wide applications in mechanical protection yet the design and synthesis of them is a big challenge. Inspired from the bones, dual functional composites with stiff-soft microstructure have been designed and synthesized, whereas polydimethylsiloxane (PDMS) and fly ash cenospheres (FACs) were adopted as soft matrix and stiff filler, respectively. The as-prepared composites exhibited low density (0.668 g/cm3), low thermal conductivity (0.39 W/mK), and high specific energy absorption capacity (8.13 J/g at 2.8 × 10−3 s−1 and 15.49 J/g at 3000 s−1). Besides, the enhancement mechanism of energy absorption is proposed, and a percolation threshold of 60 wt% FAC contents has been revealed. In sum, the proposed study may open a new and simple strategy to synthesize lightweight energy absorption and thermal insulation composites.

Aluminum foam to improve crash safety performance: a numerical simulation approach for the automotive industry

Aluminum foams have recently received special attention due to their peculiar mechanical properties. For example, their energy absorption capacity in crash events and low density are very desirable characteristics for several applications. Actually, the energy absorption of aluminum foams is even magnified when they interact with aluminum tubes or when tubes are filled with aluminum foams. Since the automotive industry constantly demands light materials with high strain energy absorption capacity to reduce fuel consumption and fulfill safety requirements, aluminum foams are an excellent alternative to satisfy such demands. This work shows, by numerical simulations of reduced and full vehicle models, the usefulness of aluminum foams incorporated in a car structure when subjected to “35 mph Frontal Barrier Impact Test”, according to the Federal Motor Vehicle Safety Standard No 208 (FMVSS). Foam was used to dramatically improve load capacity and crush displacement. Thus, dash panel intrusions and acceleration gradient were reduced, increasing the vehicle safety performance. Finally, it is shown that foams can be beneficial in electric vehicle development by increasing load capacity.

Manufacturing of Ecofriendly Bricks Using Microdust Cotton Waste

Large amounts of cotton microwastes are accumulated in textile industries. The cotton microdust is less to ignite and causes serious environmental problems and health hazards. This paper presents an experimental study, which investigates the potential use of cotton microdust to produce new and lightweight brick for construction industries. The physical and mechanical properties of brick mixes having different levels of cotton microdust ratio were investigated. The test results recorded for compressive strength, unit weight, and water absorption values satisfy the relevant required standards for normal construction bricks. The results show that the replacement of clay soil and cement by cotton microdust does not exhibit a sudden brittle fracture even beyond the failure loads, indicates high energy absorption capacity, reduces the unit weight dramatically, and introduces smother surface compared to the current concrete bricks in the market. The results also show that usage of cotton microdust with different mixing ratios for bricks will give light-weight composite, and brick could be an economical alternative to be used for partition of board concrete blocks and sound barrier panels.

Investigation of carbon nanosprings with the tunable mechanical properties controlled by the defect distribution

The effect of defect distribution and pitch length of carbon nanosprings fabricated by different construction methods on their tensile and compressive mechanical properties is comprehensively studied. Twelve examples of nanosprings with various defect distribution are constructed according to three widely used methods based on two parent toroidal carbon nanotubes (TCNTs). Their mechanical performances are studied by using molecular dynamic (MD) simulations through tensile and compressive tests. The results reveal that the spring constant, ductility, strength, gravimetric energy density and deformation process obviously depend on the defect distribution, indicating that the mechanical properties of nanosprings can be enhanced greatly by skillfully introducing defect distribution for specific purposes. Remarkably, the tensile stiffness (1.89–68.13 nN/nm) and ductility (84%–794.8%) can be adjusted by changing the defect positions and geometries of nanosprings. The force-strain curves of nanosprings under tensile loads show sawtooth-like patterns and the oscillations of force-strain curves can be controlled by the defect distribution to produce the high energy absorbing capacity. Furthermore, all nanosprings show excellent reversibility under compressive loads, and energy storage densities ranging from 53.31 to 859.67 J/g are achieved by adjusting the defect distribution and pitch length. The findings are meaningful for scientists to design carbon nanosprings with high performance.

Numerical 3D Finite Element Assessment of Bending Moment-Resisting Frame Equipped with Semi-Disconnected Steel Plate Shear Wall and Yielding Plate Connection

Steel plate shear walls (SPSWs) have advantages such as high elastic stiffness, stable hysteresis behavior, high energy absorption capacity, and decent ductility. However, one of the main drawbacks of SPSWs is their buckling under lateral loading. To address this issue, a simple and practical solution in the form of using a trapezoidal plate moment connection (PMC) and a narrow gap between the infill plate and columns is presented. The PMC will act as an energy absorber, similar to a yielding steel plate, and keep the other structural members in an elastic state. Extensive three-dimensional finite element (FE) models of the SPSW system were investigated under monotonic and cyclic loading. The results revealed that by separating the infill plate from the vertical boundary elements and using two vertical edge stiffeners at both edges of the wall, the same lateral bearing capacity of the conventional system can be achieved. In addition, by increasing the thickness of the PMC from 6.5 to 26 mm, the load-bearing capacity, energy dissipation, and elastic stiffness increased approximately 2, 2.5, and 3.2 times, respectively. It was also found that the flexural capacity ratio of the connection to the beam had little effect on the overall force–displacement behavior. However, it can affect the system failure mechanism. Finally, the tension field inclination angle for such SPSWs was proposed in the range of 30 to 35°.

Numerical simulation of void growth in front of a blunting crack-tip in plastically compressible solids

Effect of plastic compressibility on void growth ahead of a moving crack-tip is investigated numerically for a mode I crack subjected to plane strain deformation with small-scale yielding. Exploration is made for quasi-static finite deformations of isotropic hardening elastic–viscoplastic solids. For comparison purpose, both plastically incompressible and plastically compressible solids are considered to study the crack-tip deformation, void growth and interaction between the crack-tip and a nearby void by examining the near tip distributions of plastic strain, hydrostatic stress, effective stress and stress triaxiality. The plastic compressibility is found to have strong effect on the crack-tip deformation and stress–strain fields in the ligament and void region. The shape of void growth in front of the crack-tip is significantly influenced by the plastic compressibility. The present results show that in the case of plastically compressible solids, the rate of void growth in the direction perpendicular to the crack plane is more than the corresponding in the direction parallel to the crack and this observation is in sharp contrast to the void growth behavior observed in plastically incompressible solids. The predictions of the crack-tip and void interaction in the presence of plastic compressibility may be very helpful in understanding the crack growth and void coalescence in some relatively newer materials having very high energy absorption capacity, highly desired electrical and thermal as well as radiation-resistant properties, properties of bioimplants, etc.

Hybrid Auxetic Structures: Structural Optimization and Mechanical Characterization

With their increased energy absorption capacity, auxetic materials are perfectly fit to develop new, enhanced lightweight crash absorbers for cars. Herein, the mass distribution along the struts is optimized via finite element analysis with a parameterized optimization. Four different auxetic unit cells are taken from the literature and their struts parameterize, the models simulate, and the mass specific energy absorption capacity optimizes. The two models with the highest energy absorption capacity are then selected for experimental investigation and produced by additive manufacturing from a polymer. To further enhance the mechanical properties, the specimens are electrochemically coated with nickel and the polymer molten out by pyrolysis. Those Ni/polymer hybrids are subjected to quasistatic and dynamic impact experiments. Only a small strain rate sensitivity can be detected under dynamic loading, namely, a higher plastic collapse and higher plateau stress. The hollow struts are folding instead of bending, which render them much weaker than predicted by the simulation. In conclusion, it is possible to improve existing crash absorber elements with tailored auxetic hybrid structures. They absorb higher amounts of energy without changing their stiffness under dynamic loading while saving mass and cost.

Axial Crush Response of Aluminium Square Tube with Origami Patterns

Thin-walled square tubes are widely used as impact energy absorber in automotive structures due to their ease of fabrication and installation, high energy absorption capacity in terms of progressive plastic deformation and long stroke. However, the main drawback of square tube is its high initial peak force during the initial stage of crushing. An origami pattern on the faces of the tube is proposed to reduce the high initial peak force and increase the energy absorption of the tube. Static and dynamic axial crushing were performed using finite element analysis to determine the initial peak force (IPF), crush force efficiency (CFE) and plastic specific energy absorption (SEA) of tubes with origami pattern. The results of simulations were validated by experimental data. Then, various combinations of origami patterns were studied using finite element simulation only. It was found that the origami pattern significantly enhanced the tubes crush performance. Comparison between plain square tube and tubes with various origami patterns was carried out and it was found that the origami patterns reduced the initial peak force and increased the crush force efficiency for both static and dynamic loading conditions.

Uniaxial compression of bi-directionally graded lattice structures: Finite element modelling

Lattice structures are widely used in various engineering applications due to their high weight-to-strength ratio and exceptional energy absorbing performance. The feasibility of using different base materials to fabricate these cellular structures with complex geometries has been significantly broadened with the development of additive manufacturing technology. In this paper, quasi-static mechanical properties and energy absorption capability of polyamide PA 2200 (nylon 12) lattice structures were investigated by using finite element analysis (FEA) in ANSYS/LS-DYNA. Three types of lattice structures composed of body-centred cubic (BCC) unit cells were studied, including uniform lattice structures, uni-directionally graded lattice structures and bi-directionally graded structures. Finite element simulations were consistent with experimental data reported in literature. The results showed that bi-directionally graded lattice structures exhibited superior crushing resistance and higher energy absorption capacity than uniform and uni-directionally graded lattice structures. It showed that density grading design of lattice structures had significant influence on the deformation patterns and therefore, energy absorption performance.

Experimental and Numerical Study on the Energy Absorption of Polyurethane Foam-Filled Metal/Composite Hybrid Structures

Hybrid structures have the advantage of combining different types of materials at the same time. The trend of lightweight design in the transportation industry has promoted the development and application of composite materials with good crashworthiness performance. Low-density crushable foam-filled metal-composite hybrid structures have potential advantages as energy-absorbing components. This study investigated the mechanical characteristics of four different polyurethane foam-filled hybrid structures and their individual components under quasi-static axial compression. The experimental results showed foam-filled hybrid structures could change the deformation mode and improve stability during the compression process. Meanwhile, these hybrid structures could also improve energy absorption compared with their individual components. Among the different configurations, specimen C-PU-C (i.e., polyurethane foam filler between an outer CFRP tube and an inner CFRP tube) had the highest energy absorption capacity, at 5.4 kJ, and specific energy absorption, at 37.3 kJ/kg. Finally, a finite element (FE) model was established to analyze the mechanical characteristics of the hybrid structures by validating the simulation results against the experimental results.

Investigating the Feasibility of a Cushion Selection Method on Polyethylene Based on a Predictive Model

Cushion materials are very popular and widely used in various applications. Cellular solid has been used for cushioning for many years due to its low weight and high energy absorption capacity. Cushioning selection is the process of selecting a cushioning material to sufficiently cushion an object. There are a few cushion selection methods available in literature. The objective of this report is to investigate the feasibility of a cushion selection method based on predicting the impact absorption capacity from static compressive stress-strain data. This is achieved by comparing the predicted dimensionless deceleration (G) and the measured G. Polyethylene (foam) samples were used to conduct the compression test and drop test. For polyethylene, the predicted G shown higher accuracy at low drop height and became lower accuracy with increasing drop height. A dynamic factor C was introduced to account for the difference. From this report, researchers may explore the feasibility of this cushion selection method on polyethylene or even conduct experiments on other cellular solid specimens in the future.

Effect of foil thickness and cell size of honeycomb on energy absorption of aluminium honeycomb sandwich composite (Charpy Test)

Sandwich composites are special class of materials because of peculiar properties such as lightweight, high energy absorbing capacity, and high damping, etc. These properties make them suitable for their use in aerospace and marine industry. Generally, metal or FRP sheets are used as skin/face sheet and honeycomb, foam and balsa wood, etc. are used as core materials. The elastic properties of the honeycomb are the function of foil thickness and cell size. In the present study, the effect of parameters (Foil thickness and Cell size) of the honeycomb on the energy absorption capacity of the sandwich composite was investigated through experimental and numerical studies. Experiments were carried out on four sandwich composites having a variable combination of foil thickness, and cell size by using the Charpy ASTM E-23 machine. Further, numerical analyses were carried out using finite element (FE) software Abaqus. The experimental and numerical results were found to be in good agreement. The results show that energy absorption to mass ratio increases with the increase in foil thickness and with the decrease in cell size. For the improvement of energy absorption to mass ratio, the effect of change in the foil thickness is significant compared to that of change in cell size. Failure mechanism was discussed through numerical study. The impact force resisted by the sandwich composites was presented by using the impulse-momentum equation.

Performance evaluation of high-strength concrete reinforced with basalt fibers exposed to elevated temperatures

This study experimentally investigated the effectiveness of the inclusion of basalt fibers in concrete to enhance the performance of the concrete components when exposed to elevated temperatures. Concrete specimens were reinforced with basalt fibers at dosages of 0.25%, 0.5%, 0.75%, and 1%, and then exposed to high temperatures of up to 600 °C. Chopped basalt fibers act as fillers and bridge the gaps and micro-cracks within concrete, resulting in the high strength and energy absorption capacity of basalt fiber-reinforced concrete. At elevated temperatures, when the surface-bound water becomes evaporated, additional stress was found to be released through the softening of basalt fibers. Moreover, at such high temperatures, basalt fibers held the aggregates and cement paste in position by gripping the macro-cracks when the hydration products of concrete began to decompose. The residual strength in fiber-reinforced concrete was thereby significantly higher than that in non-fibered concrete. However, beyond the optimum level of fiber addition, agglomeration, and the non-uniform dispersion of fibers was observed, which results in the lowered performance of the concrete.

Understanding and suppressing shear band formation in strut-based lattice structures manufactured by laser powder bed fusion

The formation of shear band in metallic lattice structures under compression prompts an unstable stress–strain curve, resulting in a significant reduction in the energy absorption capacity. The development and formation of shear band need to be clarified, and versatile approaches to suppress the shear band are required. In this study, we explored the formation mechanism of shear band using a representative Al–12Si alloy lattice structure, consisting of a simple body-centered cubic (BCC) unit cell manufactured by laser powder bed fusion. The X-ray computed tomography observations of an interruptedly compressed lattice specimen and finite element analyses revealed that the crack initiations in the bent struts under the localized tensile stress trigger the formation of shear band. Accordingly, an attempt was made to fabricate various lattice structures consisting of BCC unit cells with different strut diameter ratios to suppress shear band formation. Finite element analyses revealed relaxed tensile stress inside the struts with the controlled diameter ratios, suggesting the suppressed formation of shear bands; this was demonstrated by compression tests. The present results provide new insights for achieving a stable compressive deformation and high energy absorption capacity of lattice structures.