The study presents the mechanical performance, particularly energy absorption ability, under uniaxial quasi-static compression of aluminium foams fabricated by melt processing with CaCO 3 blowing agent and B 4 C+TiB 2 powder with content varied from 30 to 70%. High-strength Al6Zn2.3Mg alloy comprising brittle eutectic domains was employed for manufacture of the foam. The optimal amount of B 4 C + TiB 2 powder was determined to be 50% at which it results in the highest energy absorption. The key role of identity sizes for B 4 C + TiB 2 and CaCO 3 powders for the efficiency of the foaming process with the formation of certain particle configurations in the melt was examined and discussed. The results of the present study could be helpful for selecting the aluminium alloy and additives for the foaming process and providing a certain level of the mechanical properties, particularly, energy absorption ability.

Wire arc additive manufacturing (WAAM) is an emerging metal 3D printing technology, and it is deemed to be suitable for constructional sector due to its high fabrication speed, flexibility, and cost efficiency. This paper investigates the geometric characteristics and mechanical properties of WAAM S308L stainless steel plate and tube through experimental investigation. 3D scanning was employed for geometric measurement to reveal the variations in the geometric properties of the WAAM S308L specimens. In addition, the monotonic tensile test, Vickers hardness test, bend test, and Charpy V-notch impact tests were conducted to assess its mechanical properties. The effects of specimen shape and loading directions relative to the material deposition orientation on the mechanical properties were examined. Material anisotropy behaviour was observed, as the 45° specimen exhibited 14% higher strength and an 80% higher Young’s modulus compared to the 90° specimen. Excellent ductility was found, as indicated by the values of ratios σ u / σ 0.2 ≥ 1.1, ɛ u / ɛ 0.2 ≥ 15, and ɛ u ≥ 15%. The 45° sample exhibited approximately 8% greater impact energy absorption ability than the 90° sample. Curved tensile specimens exhibited a 20% higher 0.2% proof strength than plate specimens. Based on the tensile test results, the Ramberg-Osgood model is adopted to describe the full range of the stress-strain curve. Additionally, the plane orthotropic model and Hill’s yield criterion are used to accurately model the material’s elastic and plastic anisotropic behaviour. Overall, the investigated WAAM S308 L stainless steel exhibited obvious anisotropy in the mechanical properties, with qualified strength, ductility, and impact toughness for engineering practice.

The growing menace of the blast and impact events on the critical infrastructure requires extensive knowledge on the behaviour of the high-strength concrete (HSC) under extreme loading. The study explores the blast and impact resistance of HSC columns both experimentally and numerically in terms of the nature of energy absorption, the patterns of damage development, and the transitions of failure modes. The four groups of HSC columns with concrete compressive strengths of 60 to 120 MPa and reinforcement ratios of 1.5% up to 4.0% were given controlled blast loads at scaled distances of 0.5 to 2.0 m/kg (1/3). The findings have shown that a doubling of concrete strength, to 120 MPa, raises blast resistance by about 45 per cent and higher reinforcement ratios (more than 3.0 per cent) raise ductility and energy-absorbing ability by 38 per cent. The experiment identifies three failure modes, flexural-dominated failure in scaled distance greater than 1.5 m/kg (1/3), shear-dominated failure between 0.8 to 1.5 m / kg (1/3) and direct shear failure below 0.8 m/ kg (1/3). Microstructure analysis indicates that HSC has better performance as it has denser matrix structure and low porosity, and incorporation of nano-silica results in further 15-20 percent improvement of blast resistance. The results are essential in the optimization of the design of the blast-resistant structures and the performance-based design criterion of the HSC column of high-risk facilities. The study enhances the comprehension of concrete behaviour during dynamic extreme loadings, and leads to the better safety practices in protective structural engineering.

Synergistic design of curved beam metastructures with tunable stiffness, Poisson's ratio and energy absorption ability

This study investigates the deformation capacity factor (m) of composite columns using experimental data and finite element numerical modeling. The real behavior of these columns was analyzed using the Krawinkler–Ibarra cyclic loading protocol, and parameters such as deformation capacity, modified axial resistance, and hysteretic behavior were assessed to evaluate energy absorption ability. The research combines numerical analyses in finite element software and experimental results from concrete-filled steel tube (CFT) columns. Force-displacement curves under cyclic loading were extracted, and by identifying key points on the curve (yield, maximum, and failure points), the deformation capacity factor (m) was calculated according to the FEMA 356 guidelines and the Iranian code (publication 360). The results showed that the m factor for CFT sections ranges from 1.4 to 5.6, while for SRC sections, it ranges from 1.0 to 4.0. At axial loads exceeding 50% and 65% of the nominal capacity, respectively, the behavior of CFT and SRC sections shifts from deformation-controlled to force-controlled. Additionally, an empirical relationship for predicting axial load capacity was developed, improving the accuracy of predictions compared to common models. The findings indicate that CFT composite columns exhibit significant deformation capacity, and their m factor exceeds the values recommended in codes in most cases. This study contributes to a better understanding of the nonlinear behavior of composite columns and the optimization of seismic design, especially for retrofit projects.

In order to study the application of steel fiber rubber concrete (SFRuC) in impact resistance and maintenance structures. This study, the effects of two key variables-rubber content (0%, 3%, 6%, 9%, and 12%) and impact velocity (3 m/s, 6 m/s, and 9 m/s)-on the dynamic behavior of SFRuC were systematically investigated. Dynamic splitting tensile tests were conducted using a 50 mm diameter Split Hopkinson Pressure Bar (SHPB) apparatus. The results reveal that increasing rubber content leads to a gradual reduction in peak stress. Notably, specimens with higher rubber content exhibited an extended post-peak plateau, indicating improved energy dissipation. In contrast, increasing impact velocity produced a linear increase in peak stress, suggesting a rate-sensitive response. These findings suggest that rubber content and impact velocity jointly influence the fracture characteristics of SFRuC. An optimal combination of these parameters can significantly enhance the material’s energy absorption capacity. The toughness index, which reflects this energy absorption ability, was found to be strongly dependent on both variables. Furthermore, Scanning electron microscopy (SEM) revealed two primary failure modes: fiber pull-out and fiber fracture. In mixtures with higher rubber content, energy dissipation predominantly occurred through fiber pull-out. When the applied stress exceeded the tensile strength of the fibers, fiber breakage became the dominant mechanism, often accompanied by matrix spalling. Overall, this research supports the viability of utilizing steel fiber-reinforced rubber concrete in impact-resistant and protective structural applications. To gain a comprehensive understanding of its applicable scope within the structural context, further in-depth research is required.

ABSTRACTNatural fiber‐reinforced thermoplastic composites have gained increasing attention due to their sustainability. Additive manufacturing, particularly Fused Deposition Modeling (FDM), enables the fabrication of such composites with complex geometries. This study investigates the mechanical behavior of wood‐polylactic acid (PLA) composites fabricated via FDM, focusing on their tensile and fracture properties under different water absorption durations. Results indicate that wood‐PLA exhibits reduced tensile strength and stiffness compared to pure PLA. The tensile strength for wood‐PLA was 23.4 MPa, which was significantly lower than the strength of the PLA (54.6 MPa). However, the wood‐PLA showed enhanced strain energy density in the tensile test, measuring 1.41 times greater than the PLA, and higher energy absorption ability in the Single Edged Notched Bending (SENB) test. Water uptake induced plasticisation effects in the wood‐PLA composites, resulting in a 20% reduction in strength and a 10% decrease in elastic modulus after 15 days. Moreover, elongation at break increased by 66%, contributing to a 48% improvement in energy absorption. Notably, these effects are reversible upon redrying, suggesting that water primarily acts as an external plasticizer. The study highlights the mechanical response of wood‐PLA composites and provides insights into their structural integrity in humid environments.

Air blast attacks are rapidly increasing in the current scenario, resulting in lots of people severely injured and losing their lives, and infrastructures are critically damaged. Honeycomb sandwich panels have outstanding specific strengths with efficient energy-absorbing ability and are widely employed as protective panels against extreme air blast loadings. Improvement in the air blast mitigation performance of the honeycomb sandwich panels without increasing their mass and volume occupancy is the challenging task for weight-critical applications. Therefore, in the present explicit numerical study, the effect of honeycomb core topologies (square, reentrant, octagonal, and circular) on the blast performance of the high-strength AL-6XN sandwich panels is investigated at constant mass and volume for 1–3 TNT air blast loadings. The unit cell volume occupancy of the different honeycomb cores is also maintained constantly. The rate-dependent Johnson-Cook material model was used for achieving realistic plastic deformations in the designed sandwich panels. To identify an optimal honeycomb core design, the blast performance of the designed honeycomb sandwich panels of the equal mass is compared in terms of their face sheets center point deflections, face sheets radial deflections, changes in kinetic energy, changes in internal energy, plastic dissipation energy (PDE), deformation modes, and equivalent plastic strain (PEEQ) of the core structures. The obtained results indicated that the circular honeycomb core used sandwich panels have better blast resistance than the other designed sandwich panels of the identical mass in terms of smaller back face sheet’s center point deflection and radial deflection and higher energy absorption by the core structure. Hence, the circular honeycomb core is the most suitable candidate for designing protective structures against blast attacks, such as skid plates of armor vehicle.

This research has an urgency to develop environmentally friendly materials as an alternative to synthetic fiber-based composite materials that are widely used in the automotive, construction, and manufacturing industries. This research develops bamboo fiber-based composites that have advantages such as corrosion resistance, lightweight, inexpensive, and competitive in strength with metal materials. The goal of this development is to produce a lightweight, strong, and elastic material, which can be applied to a variety of products. The composite sample was made using an epoxy resin matrix using the hand lay-up method. Three variations of fiber volume fractions (10%, 20%, and 30%) were used to explore their effect on load distribution and energy absorption ability during impact. The results showed the highest value of 0.552 J/mm2 at Sp30.6, which was a fiber volume fraction of 30%, while the lowest value at Sp10.4 was a 30% volume fraction of 0.0251J/mm2. This shows that the increase in the volume fraction of petung bamboo fibers in the epoxy matrix significantly increases the impact toughness of the composite. This research is expected to determine the optimal composition to produce the best impact strength, so it is expected to produce an ideal material configuration for sustainable industrial applications.

Multi-stable mechanical metamaterials based on the snap-through behavior of cosine beams have been shown to have significant potential in the field of capacity absorption due to their advantages such as reusability and structural simplicity. However, traditional multi-stable metamaterials have exhibited limitations in both energy absorption and trapping ability. Inspired by the bionic multilevel structure, a novel hierarchical multi-stable cylindrical structure (HMCS) based on cosine curved beams is proposed. We investigated the snap-through behaviors and energy absorption capacity of the HMCS. Both finite element simulation results and experimental results show that the hierarchical multi-stable structure exhibits excellent specific energy absorption and energy trapping capabilities compared to traditional multi-stable cylindrical structures (TMCSs). Furthermore, by analyzing the effect of height h and thickness t on the snap-through behavior of the structure, the key parameters determining the mono-stable or bi-stable response are identified. In addition, a gradient-based study of the structure reveals the dominant role of stiffness in the snap-through behavior of multilayer structures. This work provides insights into the application of multi-stable cylindrical structures in energy trapping and absorption and offers a new strategy for designing high-efficiency energy-absorbing metamaterials.

Abstract In recent times, large language models have become popular in materials science for the development of new materials and formulations. An attempt is made in this work to utilize large language models such as the ones used in commercial ChatGPT versions for artificial intelligence applications. In this paper, an assessment is made for the energy absorption in rubber formulations during different cycles of loading and unloading which is intended to stabilize stress softening in rubber-like materials and in each case for the same maximum load. The experimental data obtained by earlier investigators is used for this purpose. Chat GPT4o has been used for the purpose for which the graphical data has been culled from the graphs available for Mullins effect using the commercially available graphical plotting and analysing software. No attempt is made here to go into reasons for behaviour in Mullins effect nor the various aspects of constitutive models for the Mullins effect.

Recently, the majority of studies on shear thickening fluid (STF) have considered shear rheology and viscosity, while the normal force has been neglected. Notably, investigation of the normal force is essential for elucidating the shear-thickening mechanism and expanding the practical applications of STF. Hence, in this study, a rotating rheometer was used to examine the variation in the normal force on sepiolite shear thickening fluid (Sep-STF) under different loading rates since Sep-STF exhibited a high shear-thickening performance in a prior study. The results show that the normal load-bearing capacity and energy absorption ability of Sep-STF exceeded those of pure STF. Specifically, the energy absorption capacity of Sep-STF increases by an impressive 857.40% compared with pure STF under a loading rate of 60 μm/s. An extrusion flow model derived from a piecewise power-law viscosity function coupled with the Navier boundary slip condition was proposed to analyze the velocity field and shear stress gradient distributions of Sep-STF. The normal force results obtained from this model were consistent with experimental data. Therefore, this study provides a platform allowing researchers to investigate more high-precision vibration-damping devices.

Abstract The purpose of this study is to evaluate the impact of different infill patterns on the mechanical and ballistic behaviour of 3D-printed carbon-nylon composites. The carbon nylon material was used to print samples with different infill patterns such as (Tri-Hexagon, Cubic, and Gyroid) and with an infill density of 80%. The mechanical tests such as tensile, flexural, impact, and interlaminar shear strength (ILSS) were examined on the printed samples. The results have shown that the gyroid pattern had shown better performance in mechanical characteristics. The mechanical characteristics of 3D printed samples with gyroid pattern showed improvements of 16.63% in tensile strength, 5.64% in flexural strength, 6.52% in impact strength, and 16.72% in ILSS respectively in contrast with tri-hexagon infill pattern. Micrograph evaluation was done on the damaged surfaces of tensile and flexural tested specimens. The microscopy image of the gyroid pattern’s fractured surface has revealed improved bonding, minimal voids, and no delamination, which may be the cause of the increase in mechanical properties. Besides, the micrograph image revealed that more voids in the cube pattern, are considered to be responsible for its lower mechanical performance. The high-velocity impact test was done to examine the energy absorption behaviour and damage propagation of 3D printed samples with an infill density of 80%. The findings revealed that the gyroid pattern improved their impact resistance. The ballistic impact test results show that the gyroid pattern affords better energy absorption because of its continuous structure, and efficiently disperses impact energy throughout the sample’s entire volume. The printed samples with the gyroid pattern showed a 5.24% rise in energy absorption than the cube pattern. The optimal infill density and infill pattern could be used to make materials for impact applications due to their better mechanical and energy absorption abilities.

Abstract Cellular materials are gaining popularity as constituent materials in end-use products due to their tunable stiffness and energy absorption capabilities. Additive manufacturing technologies have allowed the fabrication of these porous materials with engineered topologies. Previous works have characterized the mechanical response of cellular materials mainly under static loading scenarios; their fatigue behavior is a complex phenomenon, not yet thoroughly studied. In this work, we exploited the benefits of fused filament fabrication to build thermoplastic polyurethane cellular materials and experimentally characterize their properties under static and dynamic loadings. Three different topologies (hexagonal, re-entrant, and square) with same volume fraction were studied. A geometrical assessment was conducted on specimens to evaluate the accuracy of the selected fabrication process. Compression-compression fatigue tests (2 Hz, R = 0.1) resulted in the construction of stiffness degradation and energy absorption ability plots. Samples exhibited a loss of 30% of their original rigidity and 50% of their normalized energy absorbed after 100,000 loading cycles. Our findings comparatively illustrated the advantages between different cellular materials and the selection of thermoplastic polyurethane as constituting material in terms of fatigue life performance.

Today, lattice structures are preferred in various fields, including biomedical, aviation, and the defense industry, due to their exceptional mechanical properties, low density, high specific strength, high specific stiffness, good energy absorption ability, and excellent thermal and acoustic insulation. This study focused on investigating the mechanical performance of functionally graded hybrid (FGH) lattice structures. Three types of lattice structures were designed: triple periodic minimal surface (TPMS)-based primitive-gyroid (P-G); body-centered cubic-gyroid (BCC-G); and primitive-body centered cubic (P-BCC) hybrid lattice structures. In addition, each hybrid lattice structure was formed both in the large porosity size and in the production direction from the large pore size to the small pore size. These hybrid lattice structures were then fabricated using selective laser melting (SLM). In the results of compression tests on FGH lattice structures with large pore sizes, the P-BCC structure exhibited the highest elastic modulus among the test specimens, measuring 1573.17 MPa. The highest yield strength was found to be 128.46 MPa in the BCC-G hybrid lattice structure. Furthermore, when evaluating the energy absorption capabilities of hybrid lattice structures with a large pore size, the BCC-G structure demonstrated the highest resilience and toughness among the test samples. On the other hand, an increase in elastic modulus, yield strength, and energy absorption values was observed with the decrease in pore size. However, it was observed that the change in pore size due to defects in the production of lattice structures is another effective parameter on mechanical properties. This study suggests that desired mechanical properties can be achieved through the functional grading of pore size and the creation of hybrid structures utilizing different lattice designs.

Port fenders are crucial components in maritime operations, protecting ships and port infrastructure during docking and mooring. They absorb and dissipate kinetic energy, reducing the impact forces between vessels and docks. The fenders are constructed from various materials such as rubber, foam, and plastic, and port fenders are customized to suit different vessel sizes and environmental conditions. Their performance significantly affects port facilities' safety, efficiency, and durability. This study discusses the modification of cross-section fenders to improve the ability to absorb impact energy. This research is a simulation with finite element analysis. There has been a lot of research on the finite element method because planning fenders as an impact energy absorber is complicated and requires many extreme conditions. The cell design fender's reaction force decreased by 25.13% compared to the standard design. This reduction is excellent for protecting the ship from large forces that result in reduced ship stability when the ship hits the fender. The cell design fender's energy absorption ability increased by 10.15% compared to the standard design. The absorption of kinetic energy and its conversion into large deformation provides safety and protects the ship when berthing and docking. The results of this research consider optimal Fender design and manufacturing processes.

Abstract A detailed experimental investigation was carried out to examine the effect of montmorillonite nanoclay reinforcement on the tensile, flexural, and impact behavior of Ti6Al4V titanium‐based carbon fiber/epoxy laminates. The phenomena of crack bridging, agglomeration, enhanced adhesion between the titanium‐composite layer, and mechanical locking due to the presence of nanoclay affected the mechanical and energy absorption ability of the nanoclay‐reinforced Ti6Al4V titanium‐based carbon fiber/epoxy laminates. A high nanoclay concentration bridged the crack growth, which eventually helped localize the delamination to the impacting location alone. The agglomeration phenomena lowered the energy absorption of both low and high‐weight percentages of nanoclay. At a moderate weight percentage, the nanoclay enhanced the adhesion between the titanium‐composite layer and triggered the mechanical locking, leading to high energy absorption. Rapid preformation accompanied by petal formation and localized tearing was observed in the high‐velocity impact test. Percentage escalation in impact energy was firmly in tune with the amount of nanoclay reinforcement in the matrix. Highlights Agglomeration leads to low energy absorption for low‐weight percentages of nanoclay. FML with a moderated weight percentage of nanoclay absorbed much energy. A high percentage of nanoclay triggered crack bridging away from the impact zone. Mechanical locking and improvement in adhesion between titanium and the composite layer.

Due to air blast attacks, lots of people lost their lives or suffered from severe injuries; many buildings, infrastructures, and expensive objects were destroyed. However, efficient blast resistance structures are in major demand in the present era. Honeycomb sandwich structures are the most preferable for making protective structures against blast loads due to their outstanding energy-absorbing ability and excellent deformation resistance. The packing of honeycomb cells at constant volume significantly influences the blast resistance characteristics of the sandwich structures. Experimental evaluation of structures’ blast resistance is very costly, time-consuming, and hazardous to the environment. Hence, in this study, a sequence of explicit dynamic numerical analysis was performed to investigate the square and hexagonal packing patterns of circular honeycomb cells with vertical and horizontal arrangements impact on crashworthiness of the sandwich structures at different levels of air blast loads. The conventional weapons effect program (CONWEP) module was used to apply the air blast loads varying from 1 to 3 kg of trinitrotoluene (TNT) on the sandwich structure for a fixed stand-off distance (SoD) of 0.1 m. The rate-dependent Johnson-Cook (J-C) material model was used to obtain realistic deformations of the structures. The findings of the work represent that the horizontally arranged and hexagonal packed circular honeycomb sandwich structures provide the highest protection against blast loads due to their smallest back face deflection, uniform core crushing, and highest energy dissipation through the core at every level of air blast loadings.

Multi-objective optimization design of foam concrete mechanical properties through the integration of FEM and DL

Abstract Metallic tubular structures are significant for impact-resistant applications, with aluminium tubes offering a balance of strength and ductility. However, their crashworthiness characteristics can be further enhanced by incorporating thermoplastic polymer composite fillers. In this study, an experimental investigation was conducted on the transverse crushing performance of 3D-printed polymer composite filled aluminium tubes to evaluate their crushing behavior and energy absorption characteristics. Commercially available aluminium cylindrical tubes were used, while the polymer composite fillers were fabricated using the fused deposition modeling (FDM) technique. To analyze their transverse crushing force-deformation characteristics, the experimental setup involved quasi-static transverse compression tests on tubes with different diameters. Obtained outcomes revealed that the proposed hybrid tubes exhibited superior energy absorption due to the synergistic interaction between the aluminum tube and polymeric core. The maximum value of energy absorbing ability is 998.53 kJ/g for T-Al-PCF-60 tube which is greater than that of all the tube configurations tested. The findings highlight the potential of the proposed 3D-printed polymer composite-filled aluminum hybrid tubes as effective crashworthy structures for impact mitigation in automotive, aerospace, and protective applications.