Greater Energy Absorption Research Articles

Ballistic impact behavior of shear thickening fluid impregnated sisal fabrics

The study explores the ballistic impact performance of shear thickening fluid (STF) impregnated sisal fabric panels with varying nano silica loadings (10 wt%, 20 wt%, and 30 wt%). Rheological analysis indicated improved shear thickening behavior with increased nano-silica. FESEM, XRD, and FTIR analyses were conducted to assess changes in morphology, phase structure, and functional groups. The yarn pull-out test showed a higher pull-out force for STF-impregnated fabrics, with 30 wt% STF demonstrating the highest pull-out speed. Ballistic impact tests revealed significant improvements in energy absorption for STF-impregnated fabrics compared to neat fabrics, with energy absorption enhancements of 4.40% for 10 wt%, 45.09% for 20 wt%, and 50.17% for 30 wt%. The increased nano-silica loading resulted in greater energy absorption, attributed to enhanced inter-yarn friction and improved fabric integrity.

The structure, morphology, and optoelectronic properties of silicon nanowires decorated with GaN and Ag for single nanowire solar cell applications

This study focuses on the synthesis of a single Si-nanowire solar cell decorated with gallium nitride and silver nanoplasmons. The Si-nanowires were grown using the CVD approach followed by the decoration of their surfaces with GaN and Ag using a polyol approach. The structure of the developed GaN@Si and Ag@Si core/shell quantum wires was studied using X-ray diffraction. The morphology was investigated using scanning and transmission electron microscopy. The oxidation states were emphasized using X-ray photoelectron spectroscopy. The GaN and Ag nanoplasmons cause a modulation of the bandgap energy of the Si NWs. The growth of GaN and Ag nanoplasmons on the surface of Si nanowires increases the charge carrier density, photocurrent, and optical hole mobility. The plasmonic Ag nanoparticles suppress the nonlinear optical susceptibility of the Si nanowire compared to GaN-decorated Si NWs. The combination of quantum confinement and plasmonic effects of the proposed Ag@Si heterostructure nanowires offers great energy absorption and highly efficient separation of photogenerated electron/hole pairs. The developed single Ag@Si nanowire heterostructure exhibits photoconversion efficiency larger than GaN@Si NWs by one order of magnitude and larger than the un-decorated Si nanowires by 20-fold.

Impact Strain Signal Characteristics of Al and Mg under Instrumented Charpy Test

Impact strain signal is used to examine strain signal patterns under various parameters. Impact is a complicated phenomenon that occurs within a millisecond timeframe. Material toughness is measured by the energy absorption recorded by the Charpy machine and closely related to the specimen fracture deformation. By utilizing the strain gauge and data acquisition, the impact strain signal provides additional data regarding impact duration, maximum strain value and the area under curve for a deeper understanding of the impact problem. A material with high toughness has great energy absorption and the capability to withstand high impact load. Although magnesium is lighter in weight compared to aluminium, aluminium is a better corrosion-resistant material and is stronger, which makes it more suitable to be fabricated as automotive structural components. Tensile test is typically used for investigating a material’s mechanical properties. In the automotive industry, materials are required to have good crashworthiness. This study investigates the relationship between the energy absorbed with the power spectral density and the area under strain–time graph for different materials, impact speeds, and material thicknesses. Furthermore, the relationship between the stress–strain curve and impact strain signal were examined. In this study, the behaviour of two materials, namely Aluminium 6061-T6 and Magnesium AM60, was investigated using instrumented Charpy test, by referring to the impact strain signal pattern result. For the experiment, strain gauge attached to the Charpy machine striker was employed and linked to the data acquisition system. Charpy impact specimen has three different thicknesses; 10 mm, 7.5 mm and 5 mm. Impact speed is at 3.35 m/s and 5.18 m/s. Results show a correlation between energy absorbed with strain energy. Strain energy obtained is directly proportional to the energy absorbed. Aluminium 6061-T6 has the highest energy absorption, maximum strain, and strain energy under power spectral density graph compared to Magnesium AM60. Relation of strain signal from Charpy test and stress–strain curve from tensile test shows a significant finding where the material deforms and fracture points are identified through the signal pattern and curve. Thus, the strain signal pattern can be used to predict material behaviour.

Distal hamstrings tendons mechanical properties at rest and contraction using free-hand 3-D ultrasonography.

Tendon properties impact human locomotion, influencing sports performance, and injury prevention. Hamstrings play a crucial role in sprinting, particularly the biceps femoris long head (BFlh), which is prone to frequent injuries. It remains uncertain if BFlh exhibits distinct mechanical properties compared to other hamstring muscles. This study utilized free-hand three-dimensional ultrasound to assess morphological and mechanical properties of distal hamstrings tendons in 15 men. Scans were taken in prone position, with hip and knee extended, at rest and during 20%, 40%, 60%, and 80% of maximal voluntary isometric contraction of the knee flexors. Tendon length, volume, cross-sectional area (CSA), and anteroposterior (AP) and mediolateral (ML) widths were quantified at three locations. Longitudinal and transverse deformations, stiffness, strain, and stress were estimated. The ST had the greatest tendon strain and the lowest stiffness as well as the highest CSA and AP and ML width strain compared to other tendons. Biceps femoris short head (BFsh) exhibited the least strain, AP and ML deformation. Further, BFlh displayed the highest stiffness and stress, and BFsh had the lowest stress. Additionally, deformation varied by region, with the proximal site showing generally the lowest CSA strain. Distal tendon mechanical properties differed among the hamstring muscles during isometric knee flexions. In contrast to other bi-articular hamstrings, the BFlh high stiffness and stress may result in greater energy absorption by its muscle fascicles, rather than the distal tendon, during late swing in sprinting. This could partly account for the increased incidence of hamstring injuries in this muscle.

Fabrication, Processing, Properties, and Applications of Closed-Cell Aluminum Foams: A Review.

Closed-cell aluminum foams have many excellent properties, such as low density, high specific strength, great energy absorption, good sound absorption, electromagnetic shielding, heat and flame insulation, etc. As a new kind of material, closed-cell aluminum foams have been used in lightweight structures, traffic collision protections, sound absorption walls, building decorations, and many other places. In this paper, the recent progress of closed-cell aluminum foams, on fabrication techniques, including the melt foaming method, gas injection foaming method, and powder metallurgy foaming method, and on processing techniques, including powder metallurgy foaming process, two-step foaming process, cast foaming process, gas injection foaming process, mold pressing process, and integral foaming process, are summarized. Properties and applications of closed-cell aluminum foams are discussed based on the mechanical properties and physical properties separately. Special focuses are made on the newly developed cast-forming process for complex 3D parts and the improvement of mechanical properties by the development of small pore size foam fabrication and modification of cell wall microstructures.

Modeling and Simulation of Auxetic Materials for Balistic Protection

A type of structural metamaterials known as auxetics has a negative Poisson's ratio. Auxetic structurals have been found to possess a number of better qualities when compared to traditional ones, including: greater energy absorption, stronger indentation resistance, and enhanced mechanical properties. As a result, auxetic structures are becoming more known as a high-performance, lightweight defensive construction that can survive collisions and blasts.

Experimental and numerical investigation on low‐velocity impact response of sandwich structure with functionally graded core

AbstractThe present research investigates optimizing the impact resistance of functionally graded sandwich structures using experimental and numerical approaches. The low‐velocity impact (LVI) responses of functionally graded sandwich composite (FGSC) with different configurations with skin material jute/rubber/jute (JRJ) and core material having epoxy and sea sand by volume fraction of sea sand at 0%, 10%, 20%, and 30%. Sandwich structures were impacted with LVI (5.89, 10.92, and 15.18 m/s), with the impactor dropped from heights of 0.5, 1, and 1.5 m with precompressed spring loads. FGSC samples are considered a deformable body, and the impactor is modeled as a rigid body using commercially accessible dynamic explicit software. The burn‐out test and weight method were used to test the core's gradience; both methods' results substantially matched, and the variance in gradation could be observed. The proposed sandwich structure characteristics are examined by energy absorption, peak force, energy loss percentage, and coefficient of restitution. Results showed that SC30S provides greater energy absorption and superior damage resistance when tested on LVI. To evaluate the accuracy of experimental findings in predicting the indentation behavior of the sandwich structure, the finite element analysis was used to compare with the experimental results. According to the examination of these proposed FGSC overall performance, they could potentially be employed as sacrificial materials for LVI applications like claddings to shield major structural components. The systematic approach used in this work serves as a standard for choosing and using FGSC effectively for LVI applications.Highlights Low‐velocity impact behavior of sandwich structures was investigated. Combining flexible skin and epoxy core enhances energy absorption. Based on impact energy levels, impact damage areas were determined. Examined sandwich structure advantages in structural and aerospace uses. In terms of time and cost, the numerical analysis method would be useful.

Methodology for predicting dynamic response of multi-layer aluminum foam protected RC slabs under blast loading

Multi-layer aluminum foam with varying density distribution has been proven to exhibit significant blast alleviation capabilities under blast loads. Using the equivalent multiple degree of freedom (MDOF) method and rigid-perfectly-plastic-locking (RPPL) model, an analytical model for multi-layer aluminum foam protected RC (MF-RC) slabs is developed to predict displacement and energy properties. Studies on MF-RC slabs show that multi-layer aluminum foam with greater energy absorption causes more damage to RC slabs, revealing the limitations of the energy assessment method. RC slab displacement is used as a comprehensive assessment parameter for multi-layer aluminum foam using the pressure-impulse (P–I) diagram approach. Calculations and analyses of assessment indicators for different foam density distributions of triple-layer foam are carried out to compare their mitigation capacities under blast. Moreover, the multi-layer feedforward neural network (MFNN) is used as the surrogate model of the MDOF module, and an optimum Pareto solution between energy absorption and structural damage prevention is obtained using the non-dominated sorting genetic algorithm II (NSGA-II).

Rubberized Geopolymer Mortar and Concrete: A Comprehensive Review.

In many crucial structural applications, a material’s ability to withstand impact is of the utmost importance. The use of crumb rubber particles as a partial replacement of natural aggregates forms rubberized geopolymer concrete (RuGPC), which is found to have great impact resistance and energy absorption capacity. Geopolymer paste and natural aggregates alone are weak in handling the impact loads. The field of Civil engineering has been looking into ways for the last few years to use solid waste and ecologically friendly raw materials as components of concrete in building to embrace sustainability. Greenhouse gas emissions from cement manufacturing and the depletion of natural aggregates are two major issues the construction industry is currently experiencing. RuGPC, which combines the benefits of geopolymer concrete (GPC) and rubberized concrete to create a practical, sustainable building material, has been a hot topic for the past few years. In this paper, the fresh properties, strength and durability characteristics, mixing procedure and curing properties, dynamic and impact properties, microstructures and thermal properties of rubberized geopolymer mortar and concrete are comprehensively reviewed.

Experimental Investigation of Effect of L-Profile Hybrid Aluminium/GFRP to the Axial and Lateral Characteristic.

The current study investigates the effect of a hybrid L-profile aluminium/glass-fiber-reinforced polymer stacking sequence under axial and lateral compression loads. Four stacking sequences are studied: aluminium (A)-glass-fiber (GF)-AGF, GFA, GFAGF, and AGFA. In the axial compression test, the aluminium/GFRP hybrid tends to crush in a more progressive and stable failure than the net aluminium and net GFRP specimens, with a relatively more stable load-carrying capacity throughout the experimental tests. The AGF stacking sequence was second, with an energy absorption of 145.31 kJ, following AGFA at 157.19 kJ. The load-carrying capacity of AGFA was the highest, with an average peak crushing force of 24.59 kN. The second-highest peak crushing force, 14.94 kN, was achieved by GFAGF. The highest amount of energy absorption, 157.19 J, was achieved by the AGFA specimen. The lateral compression test showed a significant increase in load-carrying and energy absorption capacity in the aluminium/GFRP hybrid specimens compared to the net GFRP specimens. AGF had the highest energy absorption with 10.41 J, followed by AGFA with 9.49 J. AGF also had the highest peak crushing force with 2.98 kN, followed by AGFA with 2.16 kN. The most crashworthy stacking sequence among the four variations tested in this experimental research was the AGF stacking sequence because of its great load-carrying capacity, energy absorption, and specific energy absorption in axial and lateral loading. The study provides greater insight into the failure of hybrid composite laminates under lateral and axial compression.

Mechanical and energy absorption behaviors of 3D printed continuous carbon/Kevlar hybrid thread reinforced PLA composites

Over the last few years, three-dimensional printing(3DP) technology has evolved to incorporate composite materials. However, using material extrusion (ME) technology, it is still difficult to improve the stiffness with stable elongation and energy absorption of continuous fiber reinforced composites at the same time. This study aimed to 3D print hybrid threads by merging several types of continuous Kevlar and Carbon fibers. Which were created using material extrusion 3D printing to accomplish cooperative ductility and brittleness augmentation. To analyze the mechanical performance and reveal the failure and deformation mechanisms, tension tests, three-point bending tests, and drop hammer impact tests were performed. The proposed hybrids have substantially greater flexural modulus, flexural strength, tension modulus, and tension strengths with absorbed energies than standard single type fiber composites. Crack resistance during impact test of hybrid composites was enhanced by over 91% compared to carbon fiber non-hybrid composites. SEM images of hybrid specimens provided an insight of the failure mechanisms, resulting in stable hybrid composites. Positive hybrid effect further demonstrates its great energy absorption capacity.

Experimental study on temporary fastening damage of composite structures

An experimental investigation was conducted to determine the form and characteristics of damage that temporary fasteners may cause to the composite hole in the aviation temporary fastening process. According to the shapes of the temporary fastener clamping feet, copying indenters were designed. The similarity between the quasi-static indentation (QSI) experiment and the installation of temporary fasteners was discussed. The QSI experiment was used to investigate the influence of shapes of clamping feet, prepreg category, installation direction, and other factors on the failure of the composite hole, and the displacement-load curves were obtained. The damage morphology was observed with the optical microscope and ultrasonic microscope. The results show that the QSI experiment can simulate the temporary fastening damage well. Due to the expansion of delamination, and the final occurrence of fiber breakage in the composite hole, the bearing capacity is reduced. The temporary fastening damage process can be divided into three stages: in the elastic stage, the laminate does not suffer damage, and the surface resin appears slight dents; in the delamination stage, the layers delaminate at the edge of the contact surface, and expand in the direction of fiber; in the failure stage, sudden damage occurs suddenly under the indenter, and the fiber matrix is crushed into powder. The propagation range of the damage depends on the material properties and installation direction. Compared with T700/3234, T800/X850 has greater energy absorption before the damage. Laminates have the worst anti-intrusion ability out-of-plane in the surface fiber direction. These results increase the understanding of the out-of-plane compression damage of the composite material and provide a theoretical basis and method guidance for the control of the temporary fastening damage of the composite structures. The copying indenter designed in this paper can be used for further research on temporary fastening damage.

Study on the low-velocity impact response of foam-filled multi-cavity composite panels

This paper investigates the influence of lattice-web layout on the low-velocity impact performance of foam-filled multi-cavity composite panels (FMCPs). The effect of impact velocity has been explored to demonstrate the impact resistance property and energy absorption capacity. Due to the light weight and great energy absorption capacity, the FMCP with double-layer dislocation webs can be used as a good energy buffer device. An energy balance model, based on the energy absorption during impacts, was developed to predict the peak loads of the FMCPs. Numerical models were established and parametric analysis was conducted on the GFRP thickness and foam density.

Experimental and numerical analysis of the bending behavior of 3D printed modified auxetic sandwich structures

In this study, numerical and experimental investigation of 3D printed auxetic core sandwich structure has been performed through quasi-static 3-point bending testing. The flexural bending properties of a modified re-entrant structure is investigated and it's performance is compared with conventional re-entrant auxetic core. A numerical model has been developed using a commercial finite element (FE) analysis package and used for further analyzing the mechanical behavior of sandwich structures. Good agreement was observed between the experimental and FE results. It was found that the structures with modified re-entrant core outperformed with greater energy absorption (32.9 J) due to its flat pleatue area under the force–displacement curve with highest displacement (among all cases) before the failure, while the rotated version of the conventional re-entrant structure showed the maximum load-bearing capacity (1013 N).

Triangular corrugated sandwich panels under longitudinal bending

A corrugated sandwich panel consists of two face-sheets and a corrugated core, which is made of sheets that are folded into a corrugated shape. In this paper, the mechanical response of aluminium corrugated sandwich panels subjected to longitudinal loading along its middle line is investigated experimentally, numerically, and theoretically. A parametric study is conducted using ABAQUS/Explicit to examine the effects of geometric configurations (i.e., corrugation angle, core height, and core web thickness) on the deformation mode, peak force, and specific energy absorption (SEA) of panels. Two major deformation modes (Mode I and Mode II) are observed. The sandwich panels that deformed in Mode I has higher peak force and energy absorption ability. When the density of core remains the same, the energy dissipated by sandwich panels can be tailored by varying the geometry of the core. Thicker core webs result in greater energy absorption. Based on the experimental and simulation observations, a theoretical analysis using energy method is carried out to predict the crushing force of panels during large deformation.

A bionic tree-liked fractal structure as energy absorber under axial loading

A tree-liked fractal method is proposed to develop a novel protective structure with great energy absorption. Triangular, square and pentagonal tree-liked fractal structures are developed, and their mechanical behaviors and deformation processes are conducted by quasi-static axial crushing testing. The theoretical model of the tree-liked fractal structure is introduced to analyze their energy absorption under quasi-static and dynamic loads. Then, the numerical comparative study of the tree-liked fractal structure on crushing characteristics is further carried out based on high accuracy finite element model. The tree-liked fractal structure has great potential to improve specific energy absorption and crash force efficiency compared with the single-walled structure, and the 3rd order tree-liked fractal structure exhibits the best carrying capacity. In addition, the parametric design is adopted to obtain an optimal fractal coefficient and the optimal distribution of the wall thickness of the 3rd order tree-like fractal structure. Furthermore, the crashworthiness comparison of 3rd order tree-like fractal structure and typical multi-cell structures with the same mass is performed to reveal the advantage for the energy absorption. The finding of this study offers an effective design concept for developing the lightweight and efficient energy absorber.

Experimental evaluation of flexural behavior of HPFRCC beams reinforced with hybrid steel and GFRP bars

In this paper, seven beams were reinforced with the steel and Glass Fiber Reinforced Polymer (GFRP) bars in a hybrid system and the experimental behavior of beams was investigated. Three groups of beams were reinforced, including only-GFRP, only-steel, and hybrid steel-GFRP rebar subjected to four-point bending tests, respectively. To enhance the ductility of beams, conventional concrete was substituted with the High Performance Fiber Reinforced Cementitious Composites (HPFRCC). The beams of the first and second group were separately constructed by conventional concrete and HPFRCC; however, the third group was only consisted of HPFRCC. Moreover, the beams were reinforced in proportion to the percentages of the balanced ratio of longitudinal rebar. The results indicated that HPFRCC concrete positively influenced on the strength, ductility, and energy absorption of reinforced beams using composite and hybrid bars. The flexural capacity of hybrid reinforced concrete beams was between 86 and 115% of only-GFRPs and between 47 and 63% of only-steel beams and their ductility was between 88 and 235% compared to only-steel fiber reinforced concrete beams. Energy absorption in only-GFRP and only-steel samples were 50 and 34% compared to the hybrid beams. In hybrid beams, the higher ratios of effective (ρsf,f) was, the greater energy absorption was observed.

Compressive Behaviour of Aluminium Pyramidal Lattice Material-Filled Tubes.

This study focuses on the uniaxial compressive behaviour of thin-walled Al alloy tubes filled with pyramidal lattice material. The mechanical properties of an empty tube, Al pyramidal lattice material, and pyramidal lattice material-filled tube were investigated. The results show that the pyramidal lattice material-filled tubes are stronger and provide greater energy absorption on account of the interaction between the pyramidal lattice material and the surrounding tube.

An experimental investigation on mechanical performances of 3D printed lightweight ABS pipes with different cellular wall thickness

In recent years, cellular structures have attracted great deal of attention of many researchers due to their unique properties like exhibiting high strength at low density and great energy absorption. Also, the applications of cellular structures (or lattice structures) such as wing airfoil, tire, fiber and implant, are mainly used in aerospace, automotive, textile and biomedical industries respectively. In this investigation, the idea of using cellular structures in pipes made of acrylonitrile butadiene styrene (ABS) material was focused on and four different pipe types were designed as honeycomb structure model, straight rib pattern model, hybrid version of the first two models and fully solid model. Subsequently, these models were 3D printed by using FDM method and these lightweight pipes were subjected to compression tests in order to obtain stress-strain curves of these structures. Mechanical properties of lightweight pipes like elasticity modulus, specific modulus, compressive strength, specific compressive strength, absorbed energy and specific absorbed energy were calculated and compared to each other. Moreover, deformation modes were recorded during all compression tests and reported as well. The results showed that pipe models including lattice wall thickness could be preferred for the applications which don’t require too high compressive strength and their specific energy absorption values were notably capable to compete with fully solid pipe structures. In particular, rib shape lattice structure had the highest elongation while the fully solid one possessed worst ductility. Lastly, it is pointed out that 3D printing method provides a great opportunity to have a foresight about production of uncommon parts by prototyping.

Analisa Energi pada Alat Desalinasi Air Laut Tenaga Surya Model Lereng Tunggal

<p class="Abstract">The use of solar energy every day is increasing due to the greater human need for energy. the application of solar desalination equipment is classified as a renewable technology that is very profitable because the energy used is obtained for free and does not cause damage to the environment. This study examines the performance of the solar desalination device with a single slope model with a passive system. It is hoped that greater energy absorption is expected to accelerate the process of evaporation of seawater in the evaporator so as to produce lots of clean water. The desalination tool on the surface of the wall is insulated using aluminum foil with a thickness of 20 mm. The highest solar intensity was obtained on the fifth day of testing, namely 420.85 W/m<sup>2</sup> with the radiation heat transfer coefficient of 18.44 W/m<sup>2 o</sup>C, and the lowest solar intensity on the second day, namely 96.89 W/m<sup>2</sup> with the lowest total outside heat transfer coefficient of 25.57 W/m<sup>2 o</sup>C. The highest evaporative heat transfer coefficient is 10.54 W/m<sup>2 o</sup>C and the lowest is 4.42 W/m<sup>2</sup> <sup>o</sup>C. the lowest energy absorbed by the evaporator on the second day was 1.37 kWh. And the highest efficiency on the fifth day reached 58.89% and the lowest energy efficiency on the second day, namely 34.05%.</p>