Energy Absorption Capability Research Articles

A Light-Powered Self-Circling Slider on an Elliptical Track with a Liquid Crystal Elastomer Fiber.

In this paper, we propose an innovative light-powered LCE-slider system that enables continuous self-circling on an elliptical track and is comprised of a light-powered LCE string, slider, and rigid elliptical track. By formulating and solving dimensionless dynamic equations, we explain static and self-circling states, emphasizing self-circling dynamics and energy balance. Quantitative analysis reveals that the self-circling frequency of LCE-slider systems is independent of the initial tangential velocity but sensitive to light intensity, contraction coefficients, elastic coefficients, the elliptical axis ratio, and damping coefficients. Notably, elliptical motion outperforms circular motion in angular velocity and frequency, indicating greater efficiency. Reliable self-circling under constant light suggests applications in periodic motion fields, especially celestial mechanics. Additionally, the system's remarkable adaptability to a wide range of curved trajectories exemplifies its flexibility and versatility, while its energy absorption and conversion capabilities position it as a highly potential candidate for applications in robotics, construction, and transportation.

3D printed strain-hardening cementitious composites (3DP-SHCC) reticulated shell roof inspired by the water spider

Inspired by the diving bell of the water spider, this paper designs and fabricates nature-inspired 3D printed strain-hardening cementitious composites (3DP-SHCC) reticulated shell roofs. The compression performance and energy absorption capabilities of 24 specimens with eight different strut angles are evaluated through a combined experimental and simulation approach. The results demonstrate that all specimens exhibit excellent ductility and structural integrity under ultimate load conditions. The 45–45 and 60–60 specimens exhibit the highest energy absorption and efficiency, respectively, while 60–90 specimens exhibit the best ductility. Compared with traditional lightweight concrete structures, reticulated shells have lower average structural density, higher specific energy absorption, and ductility index values. A building with a proposed nature-inspired 3DP-SHCC reticulated shell roof is constructed to verify buildability, demonstrating reduced construction time and enhanced automation. This paper offers valuable insights for highly automated construction projects, especially in extreme environments.

Mechanical Characteristics of Multi-Level 3D-Printed Silicone Foams.

Three-dimensional-printed silicone rubber foams, with their designable and highly ordered pore structures, have shown exceptional potential for engineering applications, particularly in areas requiring energy absorption and cushioning. However, optimizing the mechanical properties of these foams through structural design remains a significant challenge. This study addresses this challenge by formulating the research question: How do different 3D-printed topologies and printing parameters affect the mechanical properties of silicone rubber foams, and how can we design a novel topological structure? To answer this, we explored the mechanical behavior of two common structures-simple cubic (SC) and face-centered tetragonal (FCT)-by varying printing parameters such as filament spacing, filament diameter, and layer height. Furthermore, we proposed a novel two-level 3D-printed structure, combining SC and FCT configurations to enhance performance. The results demonstrated that the two-level SC-SC structure exhibited a specific energy absorption of 8.2 to 21.0 times greater than the SC structure and 2.3 to 7.2 times greater than the FCT structure. In conclusion, this study provides new insights into the design of 3D-printed silicone rubber foams, offering a promising approach to developing advanced cushioning materials with superior energy absorption capabilities.

Developing a novel sustainable and durable self-luminous pavement material with solar energy absorption capability

Self-luminous pavement materials can autonomously absorb solar energy and emit light at night, offering a novel approach to improving nighttime road visibility and reducing energy consumption. Despite their potential, current self-luminous pavement coatings face challenges related to insufficient durability and anti-skid properties. To address this, this paper aims to develop a novel sustainable and durable self-luminous pavement material and thin layer. The development involved optimizing high-transparency epoxy resin based on mechanical properties and ultraviolet aging resistance, as well as selecting long afterglow materials based on luminous performance. Subsequently, a novel self-luminous pavement thin layer, comprising an anti-skid layer, a bonding layer, a self-luminous layer, and a sub-bonding layer, was proposed and tested. The results indicate that this novel self-luminous thin layer maintains a brightness level of 4–6 mcd/m2 after 6 h of light emission, which is still a bright level for the human eye. Additionally, it shows robust performance against ultraviolet aging, water damage, and long-term abrasion. The material cost of this thin layer is approximately 32.00 USD/m2, offering an economic advantage over mixture and pouring-in type, and it also provides benefits such as energy savings, improved traffic safety, and enhanced aesthetic appeal of scenic roads. Future efforts should focus on analyzing the economic benefits of these functions to better understand the full lifecycle advantages of this innovative material. In general, the novel durable self-luminous thin layer proposed in this study provides a practical and sustainable solution for self-luminous pavements.

Development and mechanical properties evaluation of environmentally sustainable composite material using various reinforcements with epoxy

In this study, the mechanical properties of advanced composites fabricated by the hand lay-up process were investigated. The mechanical properties evaluated in this study included tensile strength, flexural strength, and impact strength. Tensile tests were performed to measure the resistance of the composites to pulling forces, while flexural tests assessed their resistance to bending. Impact tests, on the other hand, determine the material's ability to absorb sudden forces or shocks. Results showed that all the composite materials exhibited high tensile strength, with the Carbon fiber epoxy composite displaying the highest value due to the exceptional strength of carbon fibers. In terms of flexural strength, the Glass-Fiber Polymer Matrix composite demonstrated the highest resistance to bending, while the Kevlar-Epoxy composite exhibited the highest impact strength, owing to the unique properties of Kevlar fibers, which offer excellent energy absorption capabilities. In the hardness test, the Kevlar composite to epoxy matrix showed hardness from HRB 105 to HRB 125 an increase of 19.04 %, while fiberglass increased hardness by 14.2 % and carbon fiber by 16.3 %. The Impact test shows that the Kevlar composite to epoxy matrix showed hardness from HRB 105 to HRB 125 an increase of 19.04 %, while fiberglass increased hardness by 14.2 % and carbon fiber by 16.3 %. Kevlar reinforcing composite produced the highest flexural strength, compared to neat epoxy by 91.7 %. Carbon fibre composites were 52.5 % higher, whereas glass fibre composites were 15.6 % higher. SEM imaging results from the cross-sections show that the best bonding between the base material and the fibers was observed for Kevlar reinforced with epoxy. All mechanical test showed that Kevlar (Aramid fiber) provides excellent mechanical properties when compared to carbon fibre and glass fibre. Hence, Kevlar (aramid fiber) can be an option for preparing light weight helmets, automobiles, aeronautics, safety equipments etc.

Twin-screw extrusion optimization and study of morphological, thermal, mechanical and fracture properties of sustainable Poly(lactic acid) (PLA) and Poly(butylene sebacate) (PBSe) blends

The pursuit of sustainability in material science forces the utilization of bio-based and/or biodegradable alternatives to fossil-based plastics. With growing attention in recent years, particularly in applications like packaging and agriculture, biodegradable and bio-based polymers offer potential solutions to mitigate environmental concerns associated with plastic disposal. In this context, Poly(butylene sebacate) (PBSe), a commercially available biobased and biodegradable aliphatic polyester derived from sebacic acid and 1,4-butandiol, presents a promising innovation due to its flexibility, availability in the market and compatibility with poly(lactic acid) (PLA). Up to day few works investigated the addition of PBSe to PLA, for this reason the present work focuses on comprehensively characterizing PLA/PBSe blends (with different PBSe amounts from 10 up to 40 wt%). The blends have been produced through extrusion compounding after a careful Design of Experiment for optimizing process parameters to efficiently improve mixing and energy consumption. Thermal, mechanical, and morphological properties were evaluated, combined with micromechanical analysis employing dilatometric tests. Additionally, an elasto-plastic fracture mechanics protocol was applied to quantify toughness and energy absorption capabilities, demonstrating the potential of PLA/PBSe blends in sustainable material applications. In this work also emerged the great capacity of PBSe in acting as toughener for PLA especially when is present in low amount.

A novel windmill-shaped auxetic structure with energy absorption enhancement

The traditional anti-tetra-missing rib structure often suffers from uneven stress deformation and poor energy absorption, which limits its engineering applications. To address these limitations, this paper proposed a novel windmill-shaped auxetic structure by incorporating reinforcing ligaments into the traditional anti-tetra-missing rib structure. The incorporation of these reinforcing ligaments ensures that both the outer and inner ligaments of the windmill-shaped auxetic structure are adequately supported, leading to more uniform structural deformation and enhanced energy absorption capabilities. Further modifications, such as reducing the length of the outer and inner ligaments and increasing their thickness within a reasonable range, significantly enhance the energy absorption capacity. These findings provide a theoretical basis for the design and practical application of auxetic metamaterials.

Spherical-based porous architectures: In silico design and validation

Porous (or cellular) materials, like wood and bones, are abundantly found in nature for structural purposes. Thanks to the advancements of evolving technologies, the fabrication of intricate cellular structures was possible. Notably, functionally graded porous structures offer superior mechanical and physical properties compared to their uniform counterparts. Additive manufacturing, especially light-based 3D printing (3DP) technologies, has significantly augmented the production of such materials thanks to their high speed, resolution, and cost-efficiency. However, selecting the most suitable porous architecture for one's necessities remains challenging, requiring an optimised workflow supporting 3DP methods with in silico tools to predict the functional properties of the developed porous architecture. This study introduces a preliminary step toward this workflow, involving in silico design and mechanical validation of porous architectures manufactured via low-force stereolithography 3DP. The work proposes for the first time spherical-based functionally graded porous geometries, filling the existing gap in the literature. The proposed structures, categorised upon their pore size, porosity, and pore size gradients, demonstrate potential applications in the biomedical field (e.g., tissue engineering scaffolds and soft bioreactor systems) and outperform other existing porous architectures in terms of energy absorption capabilities. These findings lay the foundation for further workflow optimisation. By coupling our fast method of generation of porous structures and a trained machine learning model to predict desired physical properties, we aim to produce functionalised cellular architectures for biomedical applications.

Experimental and analytical investigations on single and repetitive impact failure responses of composite sandwich panels with orthogonal woven GFRP facesheets and PVC foam cores

Due to the unique design requirements for high load-bearing capacity of ship structures, composite materials used in the marine industry are gradually being developed with the characteristics of multi-layer sandwich structures with large thickness and cross-section, which are different from thin-walled composite materials widely applied in the aeronautical industry. However, sandwich composite materials used in marine structures have high susceptibility to impact event during in-service applications. The impact induced damage may seriously affect their mechanical performance and structural safety. Therefore, a comprehensive investigation in this paper on the failure mechanisms of composite sandwich panels with orthogonal woven GFRP facesheets and a PVC foam core layer is carried out with a series of single and repetitive low-velocity impact tests. The variations of impact force, dent depth, structural stiffness, failure modes, energy absorption and so on of composite sandwich panels against impact energy levels and impact numbers were explored. The results demonstrate that the delamination damage threshold at the first impact, the sudden drop of peak force and the slow descent process of impact force are the three typical characteristics of impact responses that corresponded to delamination initiation and fibre breakage of the upper panel, and compression damage of the core layer, respectively. The accumulated impact-induced damage has a significant negative effect on load-bearing and energy-absorption capabilities of composite sandwich panels. Moreover, an approximate theoretical analytical method is presented to solve the impact resistance of composite sandwich panels. The analytical results are compared well with experimental results. This research provides a detailed understanding of the damage mechanisms of composite sandwich panels under impact loadings and a guidance for impact resistant design of ship protective structures.

Characterization, impact and wear properties of treated and as-received graphene nanosheets reinforcement in epoxy resin composites

PurposeThis study aims to explore the enhancement of mechanical properties in epoxy resin composites through the incorporation of graphene nanoparticles, focusing on their impact and wear resistance. It investigates the role of graphene, both treated and untreated, as a reinforcing agent in composites, highlighting the significance of nanoparticle dispersion and surfactant treatment in optimizing mechanical performance.Design/methodology/approachEmploying a novel dispersion technique using a drawing brush, this research contrasts with traditional methods by examining the effects of graphene nanoparticle concentrations treated with surfactants – Polyvinylpyrrolidone (PVP) and Sulphonated Naphthalene Formaldehyde (SNF) – on the mechanical properties of epoxy resin composites. The methodology includes conducting a series of impact and wear tests to assess the influence of graphene reinforcement on the composites' performance.FindingsThe findings reveal a marked enhancement in the composites impact resistance and energy absorption capabilities, which escalate with an increase in graphene content. Additionally, the study demonstrates a significant improvement in wear resistance, attributed to the superior mechanical properties, robust interface adhesion and effective dispersion of graphene. The use of surfactants for graphene treatment is identified as a crucial factor in these advancements, offering profound insights into the development of advanced composite materials for diverse industrial uses.Originality/valueThis study introduces a unique dispersion technique for graphene in epoxy composites, setting it apart from conventional methods. By focusing on the critical role of surfactant treatment in enhancing the mechanical properties of graphene-reinforced composites, it provides a novel insight into the optimization of impact and wear resistance.

A Comparative Blast Mitigation Performance Evaluation of Metallic Sandwich Panels with Honeycomb, Corrugated, Auxetic, and Foam Cores

Due to the high energy absorption capability and excellent bending strength of the sandwich panels, they are mostly preferred as protective structures against explosive blast attacks. The evaluation of their blast-mitigation characteristics through experiments is highly dangerous, costly, time-consuming, and polluting for the environment. Therefore, in this presented work, a series of numerical analyses were performed to evaluate the blast mitigation of the outstanding sandwich panels with honeycomb, corrugated, auxetic, and foam cores. The masses of sandwich panels were kept constant, and their areal densities were maintained constant throughout the study to effectively compare their performance under identical air blast loading conditions. To apply the air blast loads to the designed sandwiches, 1–3[Formula: see text]kg of spherical-shaped trinitrotoluene charges were used for a 100[Formula: see text]mm stand-off distance. The sandwiches are made of high-strength AL-6XN steel and crushable aluminum foam. The rate-dependent Johnson–Cook constitutive model of plasticity and the crushable foam model with volumetric hardening were used for the evaluation of sandwich panels’ plastic deformations. The findings of the work depicted that the honeycomb core is more efficient than the other core structures of the same masses because the sandwich panels with honeycomb core provide smaller back skin deflections, globalized core crushing, and higher core energy absorption than the other sandwich panels for extreme conditions of air blast loading.

Investigating the Mechanical Behavior and Energy Absorption Characteristics of Empty and Foam-Filled Glass/Epoxy Composite Sections under Lateral Indentation.

In this study, the crashworthiness behavior and energy absorption capacity of composite tubes under lateral indentation by steel rods aligned parallel to the specimen axis are investigated using experimental methods. Key parameters such as tube diameter, length, wall thickness, and indenter diameter are systematically examined and compared. Additionally, the influence of polyurethane foam fillers on damage modes and energy absorption capacity is rigorously analyzed. Contrary to conventional findings, smaller diameter specimens filled with foam demonstrate superior energy absorption compared to their larger counterparts, primarily due to enhanced compression of the foam volume. Experimental results reveal a complex interplay of damage mechanisms in composite specimens, including matrix cracking, fiber breakage, foam crushing, foam densification, foam fracture, and debonding of composite layers, all contributing to enhanced energy absorption. Increased tube thickness, length, and indenter diameter, alongside decreased tube diameter, are correlated with higher contact forces and improved energy absorption. Smoother shell fractures are promoted, and overall energy absorption capabilities are enhanced by the presence of foam fillers. This investigation provides valuable insights into the structural response and crashworthiness of composite tubes, which is essential for optimizing their design across various engineering applications.

Relationship between elastic properties and energy absorption of different types of aramid and UHMWPE composites used in ballistic protection

This study aimed to analyse composite materials' mechanical and elastic properties from various aramid and ultra-high- molecular-weight polyethylene fabrics used in ballistic armour materials. Furthermore, a comprehensive analysis was conducted to examine the correlations between the energy absorption data acquired from the low-velocity impact, dynamic compressive, and ballistic impact V50 tests performed in our prior investigations and the tensile test outcomes of these composites. The research revealed a notable correlation between Poisson's ratio, elasticity modulus values, and energy absorption capability. The composite material with the lowest Poisson ratio exhibited superior energy absorption performance in all tests. Composites reinforced with unidirectional textiles have attracted attention due to their low Poisson ratio and high elasticity modulus values, resulting in exceptional energy absorption capability.

Energy absorption of graded thin-walled origami tubes

Introducing origami with outstanding flexibility into thin-walled tubes can enhance their energy absorption performance. This paper first proposes a cutting and folding-based design route of thin-walled origami tubes which enables geometry gradients such as uniform, tapered, hourglass-shaped, and ellipsoidal shapes. Subsequently, the finite element model of the proposed tube is established and verified through comparisons with experimental results. Numerical simulation results demonstrate that the quasi-static energy absorption capability of the graded thin-walled origami tubes is closely related to the folding angle, the total number of layers, and shapes. Compared with the conventional octagonal tubes (COT), the initial peak force in the proposed origami tube experiences a dramatic reduction, reaching a maximum decrement of 70.75%, while achieving a 39.96% boost in specific energy absorption (SEA). Moreover, the incorporation of gradient shapes within the origami tubes facilitates a more predictable and controlled collapse pattern, leading to an enhanced energy-absorbing efficiency than conventional uniform origami tubes. This study provides new insights into the design of thin-walled tubes that balance energy absorption and shape.

Numerical study on the anti-collision performance of recycled foam concrete beam guardrail under vehicle collision

Recycled foam concrete (RFC) possessed excellent energy absorption capabilities and could be used in the anti-collision field. To address the insufficient anti-collision performance of existing guardrails, this paper presented a novel RFC beam guardrail by combining RFC with box-shaped steel shells. The quasi-static compressive tests and drop hammer impact tests were applied to analyze the static and dynamic mechanical characteristics of RFC with different densities and sand-cement ratios. Then, the vehicle collision performance of the RFC beam guardrail (RBG) and standard beam guardrail (SBG) was tested by LS-DYNA. The results showed that, compared with SBG, RBG had better guiding and energy absorption effects, reduced the peak vehicular acceleration by 44.15 % and the maximum guardrail displacement by 73.22 % during vehicle collisions, and mitigated the damage to the vehicle. Therefore, it is a viable way to utilize RFC to fabricate RBG, which could not only repurpose the construction and demolition wastes (CDW) but also acquire guardrails with enhanced anti-collision performance.

Extracting Geometry and Topology of Orange Pericarps for the Design of Bioinspired Energy Absorbing Materials.

As a result of evolution, many biological materials have developed irregular structures that lead to outstanding mechanical performances, like high stiffness-to-weight ratios and good energy absorption. However, reproducing these irregular biological structures in synthetic materials remains a complex design and fabrication challenge. Here, a bioinspired material design method is presented that characterizes the irregular structure as a network of building blocks, also known as tiles, and rules to connect them. Rather than replicating the biological structure one-to-one, synthetic materials are generated with the same distributions of tiles and connectivity rules as the biological material and it is shown that these equivalent materials have structure-to-property relationships similar to the biological ones. To demonstrate the method, the pericarp of the orange, a member of the citrus family known for its protective, energy-absorbing capabilities is studied. Polymer samples are generated and characterized under quasistatic and dynamic compression and display spatially-varying stiffness and good energy absorption, as seen in the biological materials. By quantifying which tiles and connectivity rules locally deform in response to loading, it is also determined how to spatially control the stiffness and energy absorption.

Shear-thickening-fluid-based meta-material for adaptive impact response

Lattice and Triply-Periodic-Minimal-Surface (TPMS) structures are widely employed in different engineering disciplines, combining interesting designs with optimal mechanical properties thanks to the capabilities of Additive Manufacturing. In this framework, a technique based on filling a 3D-printed flexible structure with a shear-thickening fluid (STF) is proposed to improve the mechanical response of the resulting bi-phase composite under impact loads in the low-velocity regime up to around 3 m/s. Test data indicate that once the critical shear rate threshold for the fluid is reached, the STF-filled structure can effectively smooth the peak acceleration by 50%, decrease the penetration depth and significantly enhance the energy absorption capability by a remarkable 85%. The proposed hybrid composite paves the way to novel functional applications, exploiting the adaptive behavior of non-Newtonian fillers. To this end, a Finite-Element model is proposed to further investigate and optimize the underlying fluid-structure interaction responsible for improvement of the dynamic compressive response.

Empowering PLA Bioplastics: Elevating applications horizon through groundbreaking Eco-Innovative Fibrillation, chain Extension, and crosslinking techniques

This comprehensive study introduces pioneering techniques in the toughening of polylactic acid (PLA) by incorporating thermoplastic polyurethane (TPU) nanofibrils, leveraging two distinct crosslinking methods to significantly enhance the material’s mechanical performance. Method 1 employs a silane/moisture crosslinking process, whereas Method 2 utilizes a tailored diisocyanate crosslinking approach, offering a more environmentally sustainable alternative. Molecular structural analysis was performed extensively by using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), rheological assessments, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Method 2 not only preserves TPU nanofibrils but also elevates the mechanical properties of PLA-TPU composites beyond the capabilities of Method 1. Notably, by leveraging the simultaneous crosslinking of TPU and chain extension of PLA with the tailored diisocyanate approach, we enhance PLA’s mechanical properties and energy absorption capabilities. These advancements are achieved without a high rubber content, which typically compromises strength/stiffness, thermomechanical stability, crystallization, and transparency of PLA. The resulting composites prepared via Method 2 display remarkable increases in tensile toughness, ranging from 30-60 MPa, and impact strength, achieving a span of 60–140 J/m. This is primarily due to the occurrence of a brittle-to-ductile transition (BDT) at only 3 wt% nanofibril TPU content while maintaining a high PLA modulus of 3 GPa. This critical balance between chain-extending and crosslinking reactions ensures the maintenance of PLA’s inherent strength/stiffness, crystallization, and optical clarity. The research presented here marks a significant shift in the development of tougher, more thermally stable, transparent, and sustainable polymer blends and composites. Method 2, with its tailored fiber size reduction (90–280 nm), and environmental consciousness, broadens the horizon of PLA’s applications.

Effect of Pore Architecture of 3D Printed Open Porosity Cellular Structures on Their Resistance to Mechanical Loading: Part I – Experimental Studies

Abstract The development of additive manufacturing (AM) techniques has sparked interest in porous structures that can be customized in terms of size, shape, and arrangement of pores. Porous lattice structure (LS, called also lattice struct) offer superior specific stiffness and strength, making them ideal components for lightweight products with energy absorption and heat transfer capabilities. They find applications in industries such as aerospace, aeronautics, automotive, and bone ingrowth applications. One of the main advantages of additive manufacturing is the freedom of design, control over geometry and architecture, cost and time savings, waste reduction, and product customization. However, the designation of appropriate struct/pore geometry to achieve the desired properties and structure remains a challenge. In this part of the study, five lattice structs with various pore sizes, with two volume fractions for each, and shapes (ellipsoidal, helical, X-shape, trapezoidal, and triangular) were designed and manufactured using selective laser sintering (SLS) additive manufacturing technology. Mechanical properties were tested through uniaxial compression, and the apparent stress-strain curves were analyzed. The results showed that the compression tests revealed both monotonic and non-monotonic stress-strain curves, indicating different compression behaviors among the structures. The helical structure exhibited the highest resistance to compression, while other structures showed similarities in their mechanical properties. In Part II of this study provides a comprehensive analysis of these findings, emphasizing the potential of purpose-designed porous structures for various engineering applications.

Energy-absorbing limitations of hard hat safety helmets in mitigating trauma from falling objects

The aim of the study was to analyze the effectiveness of hard hat helmets in mitigating head injuries from high-energy falling objects through a real-world case study, advanced numerical simulations and an uncertainty study. The study aims to answer the following research questions: (a) to what extent would the use of the protective helmet limit the kinetic energy of the falling construction prop, (b) whether the hard hat helmet would be damaged, and if so, to what extent, according to the helmet standards? A fatal construction accident involving a falling prop impact on the victim’s head was reconstructed using multi-body dynamics simulations and finite element analysis (FEA) based on uncertainty-based determination of initial conditions. The study quantified the impact energy, helmet damage and its energy-absorbing capabilities, and potential injury reduction compared to scenarios without a helmet. While the helmet absorbed significant energy (245% of the standard requirement) and reduced the Head Injury Criterion by 8–11%, the high impact energy ultimately proved fatal. This study highlights the limitations of hard hat helmets in extreme scenarios with high kinetic energy impacts. While helmets offer valuable protection, unrealistic expectations should not be placed on their ability to prevent all head injuries. The study not only enhances our understanding of the biomechanics of head injuries in such incidents but also provides practical implications for safety protocols and regulations.