Energy Absorption Capability Research Articles

Energy-absorbing performance of multi-segmented conical tubes with different connections

Thin-walled tubes are widely used in vehicle engineering due to their exceptional energy absorption capabilities. This study presents a series of multi-segment tapered tubes (MSTs) characterized by varying connection angles and segment counts. The MSTs are designed by establishing different connection angles (α) between adjacent tapered segments. A finite element (FE) model was developed to simulate axial impact loading, which was subsequently validated using the simplified super-folded element (SSFE) theory. The crashworthiness of MSTs with varying connection angles was analyzed. The following conclusions were drawn: (1) When α exceeds 10°, an increase in α leads to a gradual decline in the energy absorption efficiency of the MSTs, resulting in a “descending” load-displacement curve; (2) MSTs with α less than 0° exhibit a greater tendency to buckle under load and demonstrate a more rapid response to external forces; (3) Compared to corrugated straight tubes, the configuration featuring α = −30° and +30°, consisting of three segments and a cone angle of 7.5° (designated as MST3-7.5), significantly enhances specific energy absorption (SEA) and reduces the initial peak crushing force (IPCF).

Impact of lattice designs and production parameters on mechanical properties of AlSi10Mg in laser powder bed fusion

Abstract This study investigates the impact of lattice designs and production parameters on the mechanical properties of AlSi10Mg fabricated using Laser Powder Bed Fusion (L-PBF). The research explores the production and performance of gyroid, diamond, and lidinoid lattice structures under varying scanning speeds (600, 900, 1,200 mm s−1). Key findings indicate that scanning speed significantly influences mechanical properties and energy absorption capabilities. The gyroid lattice structure produced at 600 mm s−1 exhibited the highest compressive strength (76.51 MPa) and energy absorption (28.57 MJ m−3). SEM-EDS analysis revealed no substantial structural defects, while porosity and microstructural deformations were observed at higher scanning speeds. Finite element simulations demonstrated localized buckling and fissure formation in lattice structures under compressive loads. The study highlights the critical role of production parameters in optimizing the mechanical performance of L-PBF-manufactured AlSi10Mg, offering insights into achieving cost and time efficiencies in additive manufacturing processes. This comprehensive analysis contributes to advancing the application of L-PBF in producing complex, high-performance aluminum alloy components for industrial use.

Evaluation of polyester high-tenacity fabric and carbon nanotube reinforcements for improving flexural response in concrete beams.

This research scrutinized the effectiveness of utilizing polyester high tenacity fabrics to enhance the functionality of concrete panels. Two distinct woven fabrics with comparable strength resistance were fabricated and assessed. Concrete beams were compared in their original form and those reinforced with woven fabrics, along with beams reinforced with carbon nanotubes (CNTs) (B, BC2, BC4, BS1, and BS2). Results indicated that the textile-reinforced concrete panels displayed notably greater energy absorption capabilities post-failure under flexural loads in comparison to the control and CNT-reinforced panels. This enhanced performance was credited to the development of multiple cracking patterns in the textile-reinforced panels. The flexural behavior of the textile-reinforced panels was characterized by four discernible phases: a linearly increasing segment, a crack propagation phase featuring multiple cracking, a post-cracking phase with reduced stiffness, and ultimately, failure due to fabric rupture or debonding. Conversely, the control and CNT-reinforced panels exhibited a more brittle response post-initial cracking, with a limited number of cracks and reduced deformation capacity. The performance of the textile samples was largely unaffected by their specific characteristics, except for the fabric wrapping angle. The introduction of 0.04% CNTs marginally enhanced crack flexural resistance compared to the control and 0.02% CNT panels, owing to the varied distribution of CNTs within the matrix. Overall, the textile-reinforced concrete panels demonstrated superior load-bearing capacity, ductility, and energy absorption when compared to the other reinforcement techniques examined.

Investigation of Ductility and Damage Behavior of C/GFRP Composite Laminates under Bending Loads

Carbon and glass fabric reinforced polymer (C/GFRP) composites are extensively used in aerospace and sports industry because of their exceptional properties. However, during service, static and dynamic bending loads can ensue damage in composites affecting their strength, stiffness and energy absorption. Carbon fiber composites, being inherently brittle, are prone to sudden catastrophic fracture without ductile-like behavior of metals. This study investigates mechanical behavior and damage mechanisms of woven C/GFRP composites in on- and off-axis orientations during bending. Initially, bending tests with quasi-static loading were performed, followed by dynamic ones using an Izod impact testing apparatus. Results showed distinct behavior in on-axis CFRP laminates with brittle fracture. Off-axis CFRP samples and both on- and off-axis GFRP laminates showed signs of damage and non-linear behavior, yet they retained their ability to bear loads. Significantly, off-axis specimens of both types and on-axis GFRP laminates exhibited enhanced energy absorption capabilities without experiencing fracture, undergoing pseudo-ductile deformation. CFRP specimens were analyzed with micro-computed tomography (micro-CT), provided insights into prevalent damage modes such as matrix mircocracking, debonding of tows, delamination and breakage of fabric. While on-axis CFRP laminates experienced brittle fracture, off-axis specimens exhibited a ductile-like response attributed to matrix plasticity, cracking and fiber trellising before eventual failure.

Experimental and Simulation Study of Fiber-Reinforced and Foam-Filled Anti-Tetrachiral and Re-Entrant Structures

Negative Poisson's ratio (NPR) honeycomb structures exhibit excellent properties, including resistance to compression, impact resistance, and energy absorption. To better study NPR structures, this paper investigates two different methods to enhance the mechanical properties and energy absorption capabilities of re-entrant and anti-tetrachiral structures. Fiber reinforcement and polyurethane foam filling methods were used to address material enhancement issues, aiming to achieve structures with high specific energy absorption. Specimens were fabricated using selective laser sintering technology with three different material configurations, including nylon, carbon fiber-reinforced nylon, and glass fiber-reinforced nylon, for comparative analysis. Additionally, some specimens were filled with polyurethane foam. Quasi-static compression tests indicated that both glass fiber-reinforced nylon and foam filling significantly improved the material's stiffness, initial peak stress, and energy absorption, although the "auxetic" effect was weakened. Subsequently, finite element methods were used to simulate the deformation modes and mechanical properties of the two NPR structures, and the numerical results showed good agreement with the experimental results.

Mechanical properties of diamond-type triply periodic minimal surface structures fabricated by photo-curing 3D printing

Triply periodic minimal surface (TPMS) structures have attracted significant attention owing to their smooth surface configuration and parametric modeling properties. In this study, photo-curing 3D printing was employed to generate diamond-type TPMS structures, and micro-CT scanning revealed the presence of internal defects within the 3D printed TPMS structures. Two key design variables were explored: volume fraction and unit cell size. Quasi-static compression experiments were conducted to delve into the compression properties and energy absorption capabilities of the 3D printed TPMS structures. The findings reveal that increasing the volume fraction significantly enhances the compressive modulus, ultimate strength, and energy absorption capacity of TPMS structures. Additionally, increasing the cell size improves compression properties and energy absorption per unit volume. To predict the coupling effect of volume fraction and unit cell size on the compression performance of TPMS structures, a bivariate quadratic regression model was established. In addition, TPMS structures were subjected to load-unload cyclic experiments, shedding light on the evolution patterns of residual strain and hysteresis energy during cyclic loading. It provides insights into the design of reusable and fatigue-resistant diamond-type TPMS structures for various engineering applications.

Development of ultra-ductile strain hardening 3D printed concrete composite utilizing critical fiber volume and coarse aggregate

This study presents a promising approach of integrating coarse aggregates and steel fibers (smooth straight and corrugated) into 3D printed concrete to enhance both strain-hardening and ductility properties. The research delves into the engineering design of fiber reinforced 3D printed concrete by analysing the effect of critical fiber volume and coarse aggregate addition on concrete tensile properties. The combination of coarse aggregate and fiber enhances the material ability to withstand increasing loads by promoting plastic deformation, while mitigating the crack formation and propagation. Experimental methodology for engineering design of fiber reinforced 3D printed concrete is elucidated via critical fiber volume analysis, strain hardening analysis, and ductility assessment under direct tensile loading. The results indicate synergistic effect of corrugated fibers and coarse aggregates on the tensile properties and unlike straight smooth fiber, corrugated long fibers significantly contribute to excellent strain hardening behaviour. The new 3D printed concrete composite developed in this study exhibited distinctive yield point with high strain hardening factor (1.62), ductile factor (10.86), and enhanced energy absorption capability (+105kJ/m³). These enhanced properties make the material particularly suitable for applications in seismic-resistant structures and other load-bearing applications where ductility and energy absorption are critical.

Enhancing aviation safety: Multifunctional graphene nanostructured foams for lightweight fire suppression materials

Fuel tank fires and explosions are the primary causes of military and civilian aircraft losses and have been a major concern for the aviation and defense industries. Passive protection systems with explosion-suppression materials generate a protected environment within fuel tanks before ignition can occur and help prevent catastrophic failures. To minimize these concerns, open-cell reticulated polyurethane foams are extensively used in passive protection systems. However, fire- and explosion-related incidents are still taking place and need to be urgently addressed for aviation safety. This study investigates the effects of graphene nanostructured foams for redesigning the next-generation lightweight fire-retardant materials in aviation. Graphene foams have a unique open-cell morphology with three dimensional (3D) continuous and interconnected network structures and hollow features, which can be suitable for aircraft and defense applications. In this study, mechanical and thermal characterizations tests were conducted on graphene nanostructured foams for a better evaluation. Mechanical loading-unloading studies highlighted their outstanding mechanical energy-absorption capabilities against external loads. The thermogravimetric analysis revealed that the graphene foams provided excellent thermal properties against fire and high-temperature degradation. It was also confirmed that graphene foams uniquely manifested self-extinguishing characteristics during burning tests without catching fire or dripping for secondary fire formations. According to the tube explosion experiments, the graphene foams kept their appearance and strength after blast impacts and elevated explosion temperatures and shock waves. As a result, the proposed multifunctional graphene micro- and nanofoams offer significant potential for the next-generation fire- and explosion-suppression materials in various critical industries, such as aircraft, defense, space, drone, energy, and automotive.

Parameter-Independent Deformation Behaviour of Diagonally Reinforced Doubly Re-Entrant Honeycomb

In this study, a novel unit cell design is proposed, which eliminates the buckling tendency of the auxetic honeycomb. The novel unit cell design is a more balanced, diagonally reinforced doubly re-entrant auxetic honeycomb structure (x-reinforced auxetic honeycomb for short). We investigated and compared this novel unit cell design against a wide parameter range. Compression tests were carried out on specimens 3D-printed with a special, unique, flexible but tough resin mixture. The results showed that the additional, centrally pronounced reinforcements resulted in increased deformation stability; parameter-independent, non-buckling deformation behaviour is achieved; however, the novel structure is no longer auxetic. Mechanical properties, such as compression resistance and energy absorption capability, also increased significantly—an almost four times increase can be observed. In contrast to the deformation behaviour (which became predictable and constant), the mechanical properties can be precisely adjusted for the desired application. This novel structure was also investigated in a highly accurate, validated finite element environment, which showed that critical stress values are formed in well-supported regions, meaning that critical failure is unlikely. Our novel lattice unit cell design elevated the auxetic honeycomb to the realm of modern, high performance and widely applicable lattice structures.

Mechanical and Durability Properties of Rubberized Sulfur Concrete Using Waste Tire Crumb Rubber

The use of rubber crumbs provides a viable solution for alleviating the disposal problem of waste tires. In this study, rubberized sulfur concrete (RSC) was researched to investigate the optimal mixture proportion and to improve the mixing process in terms of compressive strength and durability performance. For the mixture of the RSC, sand, rubber particles, and micro-filler were adopted as aggregates and sulfur was used for the binding material. Moreover, two mixing processes were applied: the dry mixing process and the wet mixing process. Based on the test results, the increment of rubber particles in the mixture led to a decrease in the compressive strength for both the dry and wet mixing processes. To minimize the voids between the sand and rubber particles, the micro-filler was used at 5% of the total volume. The amount of sulfur varied slightly depending on the mixing process: 30% sulfur for the dry mixing process and 34% sulfur for the wet mixing process, respectively. Consequently, compared to the dry mixing process, the wet mixing process increased the bonding force between sulfur and rubber powder due to the simultaneous heating and combining. In toughness, the wet mixing process demonstrates a 40% higher energy absorption capability compared to the dry mixing process. For the durability performance of the RSC, the mixture with 20% rubber particles produced using the wet mixing process exhibited better corrosion and freeze–thaw resistance.

3D-printable Kresling-embedded honeycomb metamaterials with optimized energy absorption capability

Abstract Kresling origami structure has attracted significant interest for achieving extraordinary mechanical properties. In this study, we proposed a new strategy to develop 3D-printable Kresling-embedded honeycombs (KEHs) based mechanical metamaterials and achieve optimized mechanical energy absorption capability. By exploiting the twisted deformation modes and boundary constraints, various KEH reinforced metamaterials were designed, where their deformation behaviors and energy absorption properties were investigated using finite element analysis and quasi-static compression tests. Effects of orientation twisting angle, boundary constraint and crease tilting angle on the deformation behaviors of these KEH reinforced metamaterials were studied to optimize their energy absorption properties. Finally, deformation behaviors and energy absorption properties of KEH reinforced metamaterials incorporated of KEH arrays in both 2D structure and 3D structures were studied. Both experimental and simulation results showed that the proposed KEH reinforced metamaterials achieved much more stable compression behaviors and higher energy absorption capabilities than those of the traditional honeycomb structures. This study provides a novel KEH reinforcement strategy for 3D printed metamaterials with optimized energy absorption capabilities to dramatically expand their practical applications.

3D printing of biomimetic liquid crystal elastomers with enhanced energy absorption capacities

Spider dragline silks are noted for their unmatched toughness, which arises from their unique primary structure. However, the underlying mechanisms of this toughness have seldom been verified using synthetic structural materials. Liquid crystal elastomers (LCEs) are polymer networks with mechanical properties bearing high resemblances to those of spider silks, and are ideal material for mimicking the primary structure of spider silk and revealing its toughing mechanisms. This study introduces a LCEs-based energy absorption structure that mimics the primary structure of spider dragline silks via 3D printing method. This LCEs-based biomimetic structure offers superior toughness and energy absorption capabilities with a damping capacity of 90%, significantly surpassing that of both artificial and biological viscoelastic materials. We successfully demonstrated that the biological primary structure provides the highest energy absorption capacity than other structures. This superior energy absorption capability was examined through hysteresis tests and then validated through intuitive ball free-falling tests. The work will illuminate a new pathway in the development of kinetic energy buffering and absorption materials.

Mechanical, thermal, and microstructure analysis of 3D printed polyolefin elastomer-acrylonitrile butadiene styrene blends for tunable mechanical properties

Fused Deposition Modeling (FDM) has emerged as a cost-effective and user-friendly technique that has garnered significant attention in recent years. However, challenges persist when printing soft materials using FDM technology. This study proposes a solution by blending a soft polyolefin elastomer (POE) with a stiffer material, acrylonitrile butadiene styrene (ABS). A comprehensive experimental investigation utilizing a direct pellet printing method was conducted to 3D print POE-ABS blends in various ratios (10%, 30%, and 50% ABS content). The study encompassed material preparation, 3D printing, SEM (Scanning Electron Microscopy) analysis, Dynamic Mechanical Thermal Analysis (DMTA), uniaxial tensile testing, and compression testing to assess the mechanical properties and energy absorption capabilities of the 3D printed blends. The results of the DMTA showed that the blends with a higher amount of ABS have a larger area under the Tan δ curve, indicating their ability to absorb more energy. The SEM images revealed that as the proportion of ABS increases, the gaps between layers and beads become smaller. The mechanical properties of the pure printed POE, such as its elongation at break and tensile strength, were 2138% and 2.83 MPa, respectively. However, as the ABS content increased, the samples exhibited more rigid behavior, with a final transition to 50/50 ratio resulting in 9.4 MPa tensile strength and 160% elongation at break. The energy absorption test demonstrated that the sample with 30% ABS content has the highest energy absorption capability among all the tested samples. This research underscores the potential of blending soft and stiff materials to tailor properties for additive manufacturing applications, emphasizing the significance of material composition in achieving desired mechanical performance, printability, and functionality in printed objects.

Influence of projectile shape on ballistic behavior of 3D shallow straight-joint woven fabrics

This study investigates the influence of projectile shape on the ballistic behavior of 3D shallow straight-joint woven fabrics (3DSSWFs). Utilizing a series of numerical simulations, we analyze the impact resistance and energy absorption capabilities of 3DSSWFs when subjected to projectiles of varying geometries. The projectile setup includes spherical, conical, flat, and hemispherical projectiles to comprehensively assess their effects on fabric deformation, damage mechanisms, and overall ballistic performance. Results indicate that projectile shape significantly affects the penetration resistance and failure modes of 3DSSWFs. Spherical projectiles tend to cause extensive delamination and localized fabric failure, whereas conical and flat projectiles exhibit different interaction dynamics, influencing the energy dissipation patterns within the fabric matrix. The findings of this study provide critical insights into the complex relationships between projectile geometry and fabric response in 3DSSWFs. By elucidating the role of projectile shape in determining the ballistic limit, energy absorption capacity, and failure mechanisms, this research contributes to the broader understanding of impact dynamics in advanced textile structures.

Enhancing sports mouthguards with PLA + and PC: stress reduction, energy absorption, and topology optimization.

The objective of this paper was to compare the effectiveness of different materials for mouthguards in preventing oral and maxillofacial injuries during sports activities. The present study compares the stress-reduction and energy absorption capabilities of two other fused filament materials - poly(lactic-acid plus) (PLA+) and polycarbonate (PC), with Ethylene-vinyl acetate (EVA), which is the most commonly used material for mouthguard fabrication. Two human skulls were modelled, and a boxing glove simulated punches along the x, y, and z-axes with 5mm displacement with 1 kN force. Firstly, the maximum principal stress curve in the skull was compared for forces along the three perpendicular directions. Furthermore, the present study examines materials energy absorption properties, including their specific energy absorption characteristics and initial peak von Mises stresses. Additionally, a topology optimization approach is used to create an alternative design for a mouthguard to improve specific energy absorption. The model without a mouthguard showed the highest stress concentration of 32.298MPa in the teeth, followed by the EVA material, which resulted in a maximum principal stress of 28.525MPa. Fused filament 3D materials, such as PLA + and PC, on the other hand, showed better mechanical effectiveness in both lower jaw dislocation and lower maximum principal stress by 30.82% and 51.25% in the mandibular and maxillary teeth. Though EVA comparatively shows better specific energy absorption capability at 2.24kJ/kg post-optimization than PLA + and PC, the peak principal stress experienced in the mandibular region was comparatively higher. The topology optimization, however, improved the energy-absorbing capabilities of PLA + by 4.5 times, reaching 1.37kJ/kg and PC from 0.165kJ/kg to 0.38kJ/kg. This study demonstrates that PLA + and PC have better stress reduction capabilities than EVA and could be promising materials for the fabrication of mouthguards in sports activities. This study highlights the importance of topology optimization in dental materials science and engineering to develop safer and more effective mouthguard designs.

Out-of-plane impact characteristics of missing rib-plate type anti-tri-chiral honeycomb

Chiral honeycomb structures, renowned for their superior mechanical properties, find extensive application in passive safety protection and beyond. However, existing research predominantly centers on chiral honeycomb structures, neglecting discussions on the energy absorption capabilities of anti-chiral honeycomb structures subjected to out-of-plane impacts. In view of this, an innovative design method is proposed in this paper to construct a series of anti-tri-chiral honeycomb structures (MATCH-θ) with missing rib-plate and excellent crashworthiness by skillfully designing and replacing the nodal elements of the anti-tri-chiral structures. Subsequently, the effects of the constitutive angle θ and the wall thickness t of the cellular elements were investigated using a validated finite element model, revealing the energy absorption mechanism of MATCH-θ. It is shown that this type of structure has better crashworthiness performance compared to the conventional anti-tri-chiral honeycomb structure ATCH-90°. In particular, the MATCH-110° structure with t = 0.1 mm showed a 36% increase in specific energy absorption, a 36% increase in mean crush force, and a 35% increase in crush force efficiency compared to the conventional anti-tri-chiral honeycomb structure ATCH-90° with the same mass. The completion of this study provides valuable insights into the design and optimization of future honeycomb structures for crashworthiness.

High-Velocity Impact Performance of Ballistic Fabric Using Core-Spun Compound Yarns

In this paper, the usage of core-spun compound yarns in ballistic fabric to improve ballistic performance is considered, as with the use of core-spun compound yarns, the yarn friction inside the fabric is enhanced, and, therefore, the energy absorption capability of the fabric is expected to increase. Three types of fabric were developed and compared. Fa refers to a woven type made with 100% Kevlar® filament yarns. Fb was woven with core-spun compound aramid yarns, which were made of Kevlar® filament yarns spun with staple aramid fiber. Fc was woven with core-spun compound polyester yarns, which were made of Kevlar® filament yarns spun with staple polyester fiber. There were two main purposes for comparing these types. The first was to confirm if the ballistic performance could be improved with the usage of core-spun compound yarns instead of pure filament yarns. The second was to investigate if different compositions of spun fiber would influence ballistic performance. The research results are positive and quite interesting. They show that the usage of core-spun compound yarn could indeed help to increase ballistic performance and that core-spun compound aramid yarns are better than core-spun compound polyester yarns in this function. The research was carried out using both ballistic tests and FEA models.

Effect of Star-like Polymer on Mechanical Properties of Novel Basalt Fibre-Reinforced Composite with Bio-Based Matrix.

This study is aimed at developing a fibre-reinforced polymer composite with a high bio-based content and to investigate its mechanical properties. A novel basalt fibre-reinforced polymer (BFRP) composite with bio-based matrix modified with different contents of star-like n-butyl methacrylate (n-BMA) block glycidyl methacrylate (GMA) copolymer has been developed. n-BMA blocks have flexible butyl units, while the epoxide group of GMA makes it miscible with the epoxy resin and is involved in the crosslinking network. The effect of the star-like polymer on the rheological behaviour of the epoxy was studied. The viscosity of the epoxy increased with increase in star-like polymer content. Tensile tests showed no noteworthy influence of star-like polymer on tensile properties. The addition of 0.5 wt.% star-like polymer increased the glass transition temperature by 8.2 °C. Mode-I interlaminar fracture toughness and low-velocity impact tests were performed on star-like polymer-modified BFRP laminates, where interfacial adhesion and impact energy capabilities were observed. Interlaminar fracture toughness improved by 45% and energy absorption capability increased threefold for BFRP laminates modified with 1 wt.% of star-like polymer when compared to unmodified BFRP laminates. This improvement could be attributed to the increase in ductility of the matrix on the addition of the star-like polymer, increasing resistance to impact and damage. Furthermore, scanning electron microscopy confirmed that with increase in star-like polymer content, the interfacial adhesion between the matrix and fibres improves.

Dynamic Behavior and Energy Absorption of Typical Porous Materials under Impacts.

Porous materials are known for their excellent energy absorption capability and, thus, are widely used in anti-impact applications. However, how the pore shape and size impact the failure mechanism and overall behavior of the porous materials under impact loading is still unclear or limitedly touched. Instead of using homogeneous solids for the porous material model, pores with various shapes and sizes were implanted in a solid to establish the porous materials that have true porous structures, which permits exploration of the local failure mechanism. The results revealed that differently shaped holes have two different dominant deformation modes. And due to their different local stress distributions, they enter the plastic phase earlier and, thus, have higher specific energy absorption. Meanwhile, the model changes from hardening to a quasi-zero stiffness model as the hole size increases. The application of this work can be extended into the field of impact resistance.

Investigations of three-dimensional fiber orientation on mechanical impact behavior of short glass-fiber-reinforced PEEK composites

This work presents experimental and numerical investigations of three-dimensional (3D) fiber orientation on mechanical impact behavior of short glass-fiber-reinforced polyether ether ketone (SGFR PEEK) composites. The incorporation of short fibers significantly enhances the stiffness and strength of the composites while reducing the ductility, thereby, making the study of their impact response essential. To this end, we firstly manufactured the composite components using injection molding, and used the micro-computed tomography (µCT) to measure the fiber orientation distribution in 3D space for mechanical behavior prediction. Then, by studying the molded components across the thickness based on the actual observation, a distinct laminate structure with seven layers was quantitatively evaluated. A representative volume element (RVE) micromechanical computational method was developed and compared with the experimental results. Furthermore, homogenization method with the periodic boundary condition was implemented to evaluate the effective mechanical properties of the molded components. Finally, the phenomenological Johnson Cook (JC) model with fracture behavior was conducted to analyze the impact response of the injected components with different fiber orientation distributions. The new framework is demonstrated by acceptable energy absorption capability prediction of the SGFR PEEK composites.