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Highlights This paper aims to develop a novel theoretical model that incorporates the effects of local composite reinforcement using adhesive bonding on the energy absorption of aluminum structures under axial loading. The goal is to optimize energy absorption prior to any connection failures and to prevent uneven structural deformation. Moreover, it strives to reduce the structure's weight and material usage, achieving superior results compared to traditional global reinforcement techniques. The theoretical model was validated through experimental testing and finite element analysis, demonstrating good agreement with the predicted results. The results reveal that increasing the CFRP fiber angle, layer thickness, and number of layers generally leads to improved energy absorption capacity. An optimization analysis was performed to determine the optimal design parameters, yielding a fiber angle of 80°–90°, composite thickness of 1.5 mm, and aluminum thickness of 2.5 is the best configuration, offering the highest specific energy absorption and adequate peak load capacity for maximized energy absorption. The proposed model offers significant improvements over existing approaches, enhancing the predictive capabilities and practical applicability of energy absorption predictions in engineering design. A novel theoretical model for energy absorption in locally reinforced hybrid AL/CFRP structures. The influence of design parameters, such as CFRP layer count, fiber orientation, and thickness ratio. Optimization to maximize the average crushing force while meeting weight and geometric constraints. Findings can inform the design of safer and more efficient energy‐absorbing structures in various applications. [ABSTRACT FROM AUTHOR]

In recent decades, the quest for high-performance materials—those that combine low weight with high mechanical strength—has intensified. A promising solution involves composites reinforced with fiber and a polymeric matrix. However, these composite materials often exhibit deficiencies in crashworthiness. To address this issue, we investigated the incorporation of shape memory alloys, specifically nickel–titanium (NiTi), into the laminate structure. This study aimed to develop an equation, using a design of experiments approach, capable of predicting the energy absorption capacity of fiberglass and epoxy resin matrix composites upon impact, with integrated NiTi wires. Additionally, we proposed a model through numerical simulation using the finite element method to correlate with experimental analyses, thereby establishing a reliable model for future research. We selected the appropriate NiTi alloy (martensitic or superelastic) for the impact specimens through a full factorial design and dynamic mechanical analysis. After choosing the statistically superior superelastic wire, we manufactured test specimens using vacuum assisted resin transfer molding. These specimens, designed with three variables (diameter, spacing, and position in the laminate), followed a fractional factorial design. The drop-weight impact tests, conducted according to the ASTM D7136 standard, demonstrated increased energy absorption when NiTi wire was included in the composite. A non-linear numerical simulation (dynamic analysis) was performed, and its results—showing an excellent correlation with experimental data (above 95%)—validated the model. [ABSTRACT FROM AUTHOR]

Inspired by the tree fractal structure, a novel hexagonal hierarchical gradient tube with axial variable thickness (HHGAVT) is proposed and its crashworthiness performances are systematically investigated. Results show that when the axial variation coefficient of wall thickness k > 0, the peak crushing force (PCF) of HHGAVT will significantly decrease meanwhile the energy absorption maintains at a high level compared with the referenced structures under the same mass. When k > 0, the PCF and CFE of HHGAVT have absolute advantage compared with the uniform wall thickness tube. The crashworthiness performance can further increase by rational designing the distance factor δ. [ABSTRACT FROM AUTHOR]

The in-plane loading conditions of carbon fiber/epoxy composite (CFRP) and aluminum nested-tube-reinforced expanded polypropylene (EPP) blocks were empirically examined. This study used crashworthiness metrics to estimate the best design configuration under quasi-static loading rates. The experimental phase began with lateral loading testing of single and nested aluminum and CFRP specimen. In-plane crushing experiments were performed on EPP foam blocks reinforced with nested tubes. Both single and nested aluminum tubes had comparable force–response curves and maintained their load-bearing capacity throughout testing. Despite a load-carrying capacity drop above a particular displacement threshold, the CFRP specimens had superior specific energy absorption (SEA) values due to their lightweight nature. The triple-tube nested specimens with two smaller tubes exhibited the best SEA results (1.72 and 1.88 J/g, respectively, for the aluminum and CFRP nested samples). During concurrent tube deformation, the nested samples showed a synergistic connection that increased energy absorption, especially in the EPP foam blocks with reinforced tubes. The study also examined the effects of building nested specimens with aluminum exterior tubes and CFRP inner tubes, and vice versa. This method showed that CFRP tubes within aluminum outer tubes lowered specimen weight (from 93.1 g to 67.7 g) and energy absorption (from 160.2 J to 153.3 J). However, the weight reduction outweighed the energy absorption, increasing SEA values for certain composite material configurations (from 1.72 J/g to 2.26 J/g). [ABSTRACT FROM AUTHOR]

As more and more ships sail on the sea, the probability of collision between ships also increases. At present, researches more on head-on ship collisions than oblique ship collisions. According to statistical data, the probability of oblique ship collision is higher than that of head-on ship collision, and oblique ship collision may cause a wider range of structural damage. Therefore, this paper studies the damage deformation of ship side structures in oblique collision scenarios. In this paper, a simplified analysis method is proposed to predict the structural response of the struck ship's side structures by bulbous bow in oblique collision scenarios and the analytical results match well with the numerical simulation results, which verifies the accuracy of the simplified analysis method. The simplified analysis method can be used to assess the crashworthiness of ship side structures by bulbous bow in oblique collision scenarios. [ABSTRACT FROM AUTHOR]

AbstractThe crashworthiness of bionic thin-walled structures has been the subject of considerable research interest. In this article, we emulate the bi-diagonal skeletal structure of deep-sea glass sponges and construct sponge-like multicellular thin-walled tubes (SLMTT) with a parameterized ratio of the number of two distinct single-celled organisms (CSS I and CSS II). Thin-walled sponge-like tubes of varying dimensions were manufactured using selective laser melting (SLM) technology. The crashworthiness of these structures was evaluated under axial compression, transverse compression, and three-point bending conditions through experimental and computational approaches, including parametric analyses of the inner and outer wall thicknesses. The results show that SLMTT I has better crashworthiness under the three working conditions, and the SEA of BLMESI is 40.9 and 26.13% higher than that of BLMESII. under transverse compression and three-point bending conditions, respectively. Finally, a multi-objective optimization design of SLMTT I under multiple operating conditions is carried out by the second generation of Non-dominated Sorting Genetic Algorithm (NSGA-II) with the aim of obtaining the ideal structure with maximum specific energy absorption and minimum initial peak crushing force. This study offers novel insights into the design of bionic energy-absorbing structures under diverse operational scenarios. [ABSTRACT FROM AUTHOR]

AbstractChiral 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. [ABSTRACT FROM AUTHOR]

Polyurethane has been widely studied as a lightweight reinforcing material. This paper uses two types of hollow glass microspheres to modify polyurethane in different proportions to prepare a variety of lightweight cores for reinforcing carbon fiber tubes. A quasi‐static lateral compression test was performed on the reinforced carbon fiber tube to analyze the effect of reinforcement materials on mechanical properties, failure modes and crashworthiness. The results show that BR20 reinforcement material has the best effect on enhancing the mechanical properties and crashworthiness of the structure, and its energy absorption is 3.5 times higher than that of carbon fiber tubes. Hollow glass microspheres can improve the reinforcing effect of polyurethane. Lightweight cores prepared from different types of hollow glass microspheres show different failure modes during lateral compression (polyurethane and BR60 show better ductility, and BR20 shows shear failure). The BR20 and BR60 are mixed in different proportions, the reinforced polyurethane foam reinforced carbon fiber tube can have little difference in the energy absorption. The addition of BR20 and BR60 showed a large difference in the force‐displacement curve during the compression stage. A qualitative analysis is conducted based on the effect of the total energy absorption of the structure on the reinforcement materials. Highlights: The lightweight core is prepared by hollow glass microspheres and polyurethane.Reinforcement materials enhance the lateral compression performance.Reinforcement materials enhance the crashworthiness performance.Reinforcement materials affect failure modes.The proportion of BR20 and BR60 affects the performance of the lightweight core. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSOne of the remaining challenges for advancing the wide application of composite materials is to further improve the mechanical properties of composites. The fiber/matrix damage phenomenon produced by the composite model under axial loading has been observed through the establishment of a numerical model of composite damage. Axial crush tests have been performed on C-type carbon fiber reinforced polymers (CFRP) stanchions for the cargo floor structure of transport category airplanes using a finite element approach. The failure morphology and crashworthiness parameters of the specimens with different fiber layups have been recorded, and the effects of fiber orientation and angle of entrapment on the crashworthiness of the composites have been investigated. The present study demonstrates that the crashworthiness of composites can be effectively improved by fiber orientation design. Appropriate addition of 45° layer and 90° layer can effectively improve the crashworthiness of C-type CFRP laminates, and the performance of the two-angle and spiral laminates design is improved by 26% and 19%, respectively.The effect of stacking sequences on the crashworthiness of thin-walled C-type CFRP structures was investigated.The crashworthiness index and failure morphology of CFRP specimens with different fiber layup angles, layup sequences and pinch angles were analyzed.Several sets of fiber layup combinations with superior impact properties were derived from comparative analyses.A theoretical model is proposed to reveal the mechanism of the influence of different fiber layups on the crashworthiness and energy-absorbing properties of C-type CFRP. [ABSTRACT FROM AUTHOR]

Road accidents cause considerable losses to road users and to society. The steady increase in the number of vehicles leads to increased traffic volume. Therefore, there is a real need to improve passenger safety by developing passive safety systems. This article presents the results of experimental tests of structures absorbing kinetic energy, which could be used in the front section of a vehicle in order to reduce the consequences of passenger car head-on collisions. A number of crash tests of selected structures were conducted under various load conditions. An analysis was carried out of parameters enabling the authors to assess the level of energy absorption by the absorbers made, and compare these to absorbers available on the market. The tests carried out made it possible to determine energy absorption capability of the crash boxes prepared and to identify a structure exhibiting the most advantageous properties from the point of view of its prospective use. Of all of the absorbers analysed, in the context of energy absorption, it was the absorber made of glass-fibre-reinforced polyphenylene sulphide that produced the most advantageous results. Nonetheless, favourable results were obtained for all of the structures tested. [ABSTRACT FROM AUTHOR]

The continuous increase in the operating speed of rail vehicles demands higher requirements for passive safety protection and lightweight design. This paper focuses on an energy-absorbing component (circular tubes) at the end of a train. Thin-walled carbon fiber-reinforced polymer (CFRP) tubes were prepared using the filament winding process. Through a combination of sled impact tests and finite element simulations, the effects of a chamfered trigger (Tube I) and embedded trigger (Tube II) on the impact response and crashworthiness of the structure were investigated. The results showed that both triggering methods led to the progressive end failure of the tubes. Tube I exhibited a mean crush force (MCF) of 891.89 kN and specific energy absorption (SEA) of 38.69 kJ/kg. In comparison, the MCF and SEA of Tube II decreased by 21.2% and 21.9%, respectively. The reason for this reduction is that the presence of the embedded trigger in Tube II restricts the expansion of the inner plies (plies 4 to 6), thereby affecting the overall energy absorption mechanism. Based on the validated finite element model, a modeling strategy study was conducted, including the failure parameters (DFAILT/DFAILC), the friction coefficient, and the interfacial strength. It was found that the prediction results are significantly influenced by modeling methods. Specifically, as the interfacial strength decreases, the tube wall is more prone to circumferential cracking or overall buckling under axial impact. [ABSTRACT FROM AUTHOR]

Based on the conventional star-shaped tube, a star-shaped multicellular tube was proposed and designed; finite element modeling was carried out using Abaqus/Explicit software, and the accuracy of the finite element model was verified under axial impact, the crashworthiness study shows that the star-shaped multicellular tube is significantly improved compared to the conventional star-shaped tube for the same wall thickness and same mass conditions. Namely, for the same wall thickness conditions, the energy absorption of the star-shaped quadrangular multicellular tube (SSMT-4-140°) is 1.77 times that of the star-shaped quadrangular tube (SST-4-140°), and the crush force efficiency is 1.24 times that of SST-4-140°; at the same mass, the energy absorption of SSMT-4-140° is 1.17 times that of SST-4-140°, and the crush force efficiency is 1.14 times that of SST-4-140°. Subsequently, the parametric study of the number of corners N, angle between two adjacent corners θ°, and wall thickness on the star-shaped multicellular tube was systematically carried out. The results of this paper can provide valuable information toward the innovative design of multicell tube structures. [ABSTRACT FROM AUTHOR]

Thin-walled metal structures are known as an effective solution in absorbing impact energy and reducing the resulting reaction forces. The design of energy absorbers with higher energy absorption capability, lower weight and reaction forces, as well as lower manufacturing cost, has always been of interest. In this study, the effects of diameter and thickness of thin-walled Aluminum tubes on different crashworthiness criteria were investigated. To this end, different geometries were examined by simulating the uniaxial compressive test applying the finite element method. The results revealed that the optimal diameter for a simple circular tube (SCT), assuming constant length and thickness, is the smallest diameter in terms of resistance to global buckling. The SCT with an optimal diameter has the highest specific energy absorption (SEA), the lowest maximum crushing force ( F max ), and the highest crushing force efficiency (CFE). Moreover, in this study, the effect of thickness on the tubular absorber performance was numerically investigated according to four criteria: SEA, F max , CFE, and energy absorption (EA), and the optimal dimensions were obtained. Based on the results, increasing the thickness increases CFE, and increasing the ratio of thickness to diameter (t/D) increases SEA and CFE. Eventually, by applying the regression analysis, two equations were presented to calculate F max and CFE, which can be used to predict the performance of thin-walled metal tubes. Reducing the tube diameter reduces the force fluctuations during crushing. SEA increases by increasing the tube thickness specially for small diameters. As thickness-to-diameter ratio (t/D) increases, SEA and CFE increase. Three different objective functions were carried out to find the optimum tube. Obtained fitted equations predict the maximum crushing force and force efficiency. [ABSTRACT FROM AUTHOR]

Highlights In this study, the axial crushing response and energy‐absorbing mechanisms of circular composite tubes, which were reinforced by carbon fiber (C10) and carbon/glass hybrids (C3G4C3), were investigated experimentally and numerically. Both samples exhibited similar crushing responses comprising delamination and intralayer shear failure. The impact kinetic energy is primarily converted into frictional and composite damage energies. C3G4C3 had poorer crashworthiness with a mean crushing force and specific energy absorption of 313.3 kN and 58.0 kJ/kg, which are by 39.3% and 30.8% less, respectively, than those of C10. The influence of glass fiber reinforced polymers (GFRP) content (hybrid ratio) and stacking sequence on tubal crashworthiness was investigated numerically. For composite tubes with a hybrid ratio of 40%, the central distribution of GFRP (C3G4C3) achieved optimal energy absorption performance. Additionally, when GFRP layers were centralized stacked, a reduction of the hybrid ratio from 60% (G3C4G3) to 20% (GC8G) helped improve the crashworthiness of the hybrid tubes, where the mean crushing force increased by 23%. Impact responses of composite tubes reinforced by carbon fiber and carbon/glass hybrids were investigated experimentally and numerically. Carbon/glass hybrid tubes exhibited lower crashworthiness. The effects of stacking sequence and hybrid ratio on the energy absorption performance were studied. [ABSTRACT FROM AUTHOR]

In recent years, passive vehicle safety has become one of the major concerns for the automotive industry due to the considerable increase in the use of cars as a means of daily transport. Since real crash testing has a high financial cost, finite element simulations are generally used, which entail high computational cost and long simulation times. In this paper, we make use of the recent advances in the deep learning field to propose an affordable method to provide reliable approximations of the finite element simulator model that significantly reduce the computational load and time required. We compare the prediction performance in crash tests of different models, namely feed-forward neural networks and bayesian neural networks, as well as two multi-output regression methods. Our results show promising results, as deep learning models are able to drastically reduce the engineering costs while providing a feasible first approximation to the passenger's injuries in a crash event, thus being a potential game changer in the vehicle safety design process. [ABSTRACT FROM AUTHOR]

Recently, auxetic honeycombs have attracted widespread attention with characteristics of lightweight, excellent energy absorption capacity and high shear stiffness. The present paper proposes the hybrid star-shaped tetra-chiral honeycomb (STCH) by embedding the tetra-chiral honeycomb (TCH) into the star-shaped honeycomb (SSH). The deformation mode and compression behavior of the STCH were studied numerically and compared with that of the SSH and TCH. Particularly, under the impact velocity of 2 m/s, the specific energy absorption (SEA) of the STCH increases by 80 and 179% than that of the SSH and TCH, respectively. Through investigating the effect of impact velocity and relative density on the crushing behavior of the STCH, the deformation modes map was summarized, and the empirical formula of the plateau stress was presented. Subsequently, the detailed parameter analysis of the STCH revealed that in a certain range, the SEA and stability of the STCH increase with the increase of N x , θ , and R , and with the decrease of L 2 and L 1. Finally, the improved STCH (ISTCH) with stable deformation and better crashworthiness was further proposed, and the crashworthiness of it was comprehensively compared with other structures. The result shows the excellent crashworthiness of the ISTCH. Particularly, the SEA of ISTCH can be nearly 8 times higher than that of the TCH. The novel star-shaped tetra-chiral honeycomb (STCH) can absorb more energy due to the increase of plastic hinges and the complex coupling deformation. The deformation modes map of the STCH was summarized and the plateau stress was fitted. The change of radius and cell wall angle can greatly change the Poisson's ratio from positive to negative. The STCH and improved STCH have excellent crashworthiness. [ABSTRACT FROM AUTHOR]

In order to improve the crashworthiness of traditional Thin-Walled Struct, a new method for designing multicellular tubes is presented in this paper. In this work, multicellular columns based on origami centripetal folding method (MCOCFM) are proposed. The cross section of MCOCFM is designed in the way of origami. The mechanical properties of MCOCFM under uniaxial compression are analyzed by numerical simulation. Studies have shown that increased levels and wall thickness facilitate energy absorption. In addition, the theoretical prediction of MCF is in good agreement with the simulation results. Compared with some existing structures, MCOCFM has better crashworthiness. [ABSTRACT FROM AUTHOR]

Based on the requirements of the narrow installation space of a train end, compact energy-absorbing travel, and huge energy suck, a shrink tube anti-creep device was designed. The crashworthiness of different structures was studied by means of a material test, a trolley test, and numerical simulation. For every 1 mm increase in tube wall thickness, 1 mm increase in the axial length of the friction cone, and 0.01 increase in the friction coefficient, the mean crushing force (MCF) increased by 45.1 kN, 13.5 kN, and 30.5 kN, respectively. When the cone angle of the shrink tube increased from α = 5° to α = 25°, the increase in the MCF with different thicknesses was about 600%. The MCF was most affected by the cone angle, followed by the wall thickness, the friction coefficient, and the axial length of the friction cone. The change in the contact length of the friction cone of the shrink tube under different structural parameters was compared. The contact length decreased with the increase in tube wall thickness and increased with the increase in angle. The variation rule of MCF was obtained to provide a reference for the development of genealogical products. [ABSTRACT FROM AUTHOR]

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In contrast to single‐phase materials the manufacturing process of composites creates multiscale interfaces among constituent materials and between laminar multilayers. Targeting the interfaces in these composite structures, this paper presents a perspective study on the impact safety of potential future composite rail vehicles. The aim is to conceptually explore the key role of interfacial discontinuities of composite material structures as they are a critical issue affecting the impact performance of future composite rail vehicles. Following a theoretical description, the issues are addressed in two parts. First, composite materials are characteristically analyzed from the perspective of their interfacial discontinuities within the materials and between the laminate multilayers to identify their influence. Second, the structural conditions required for crashworthiness are determined in relation to the dual requirements of global stability and local deformability for efficient energy absorption. The key findings are: (1) The interfacial discontinuities of the material phases and the designed structural assemblies need to be tailored for crashworthiness performance and (2) Global stability and locally deformability are the key dual requirements for the energy absorbing progressive deformations that are essential for application of composite for crashworthiness of rail vehicles. The research conceptually explores a key issue of the impact mechanics of composite structures from the perspective of impact safety of composite rail vehicles. [ABSTRACT FROM AUTHOR]

The design and development of crashworthy vehicles depend increasingly on credible crash simulation results. This credibility requires a careful process of verification and validation (V&V). The former relates to assessing the correctness of the calculation while the latter relates to the appropriateness of the physical and numerical test results. In this context, various sources of uncertainty exist in crash tests as well as in simulation models, which can influence the validation outcomes. Hence, it is essential to study statistical validation approaches for crash applications. In this paper, we elaborate on two important aspects of validation for crash simulation models: quantification of the credibility of simulation models, and consideration of uncertainties in the validation. Limited and noisy experimental data, typical in crash applications, impose a challenge on the investigation of validation approaches. To address these challenges, we use synthetic experimental results in our study. A crash-box model is validated using the V&V20-2009 validation standard. Two case studies are considered. The first case study aims to show the application of the V&V20 approach to a crash problem. The second case is a more complex scenario and aims to explore the impact of different experimental factors, such as experimental noise, hidden uncertainties, and the number of experiments on the validation results. In the end, we examine how underlying assumptions in the validation approach affect the conservativity of the validation results. [ABSTRACT FROM AUTHOR]

To maintain the robustness of crashworthiness performance in energy absorbing structures, high specific energy absorption (SEA) and crush force efficiency (CFE) need to be maintained across a wide range of load angles. In this paper, concave design was proposed to address this issue. Finite element analysis was utilised to identify the main load-bearing elements for axial and shear loading. Furthermore, the design concepts were classified into surface variation and cross-section variation. Pattern design, which is a representative design of surface variation, can enhance crashworthiness performance by reducing the initial crushing load and maximising the development of a travelling hinge. However, there is a drawback that designing the cross-section to maximise the development of the travelling hinge leads to an increase in the dihedral angle, resulting in a decrease in the CFE. This paper proposed the concave design, that ensures excellent robustness of crashworthiness performance and minimised the trade-off between SEA and CFE performance under combined shear-compression loading. The design induces local crushing due to geometric imperfections, which reduces the peak load while maintaining the high load-bearing capacity, thereby increasing SEA. Furthermore, the surface of the energy absorbing structure is an important load-bearing component that supports shear loads, and the concave design induces progressive crushing modes for any load angle, thereby maximising the deformation of the surface and improving SEA. The structural characteristics of the concave design were validated through quasi-static loading tests. [ABSTRACT FROM AUTHOR]

This paper discusses a research study to examine the behaviour of a circular thin-walled column subjected to quasi-static axial loading. Pure aluminium and hybrid aluminium/GFRP thin-walled column were experimentally tested, then a numerical simulation model using LS-Dyna approached the results. A parametric study was investigated with several material model parameters for a deeper understanding of the woven prepreg GFRP composite modelling. It was found that the failure mode and crashworthiness parameters result would be affected by parameter variations. Therefore, the values used for these parameters were obtained by doing parameter calibration so that the load-displacement response of the thin-walled column is similar to experimental results. The further parametric study result showed that the composite layers wrapped around the outer wall could increase the capacity of the energy absorption thin-walled column. Adding thickness to the composite layers would increase crashworthiness parameters, including mean crushing force, energy absorption, and specific energy absorption under quasi-static loading. Furthermore, the proposed modelling strategy developed in this work can be used as a reference for modelling the thin-walled column made of hybrid material due to the limited comprehensive numerical parametric studies on hybrid thin-walled column. [ABSTRACT FROM AUTHOR]

Wooden fishing boats remain susceptible to accidents due to their material limitations. This study addresses this concern by comparing the crashworthiness of aluminum and fiberglass, two increasingly popular shipbuilding materials in Indonesia. Finite element simulations using ANSYS 2020 were employed to analyze deformation, stress, and energy absorption during collisions at high speeds (20 and 30 knots). The results, presented in a table, demonstrate that aluminum vessels exhibited significantly higher energy absorption (EA) compared to fiberglass counterparts. This trend held true across different material thicknesses (10mm and 6mm) and collision speeds (20 and 30 knots). For instance, at 20 knots, aluminum vessels absorbed over ten times the energy compared to fiberglass vessels with the same thickness. These findings conclusively demonstrate the superior crashworthiness of aluminum, making it a safer and more resilient material for constructing fishing boats. This research contributes to the ongoing discussion on maritime safety and has implications for promoting the use of aluminum in future shipbuilding practices in Indonesia and beyond. [ABSTRACT FROM AUTHOR]

AbstractThin-walled tubes are commonly used as crucial structures for energy absorption. It is an efficient and convenient research method to establish a small-scale model of the energy-absorbing thin-walled tube for experiments. However, due to the inevitable difference between the design velocity of the test and the actual velocity of the test, it cannot meet the traditional similarity theory. Because of this limitation, this article constructs a similarity design method for the velocity distortion of the multi-cell energy-absorbing tube at the front end of the train under axial impact. Firstly, according to the motion equation of the train system, the design criterion of the similar model under the velocity distortion is derived. Then, the collision mass correction factor is derived based on the elastic-plastic structural energy equation, aiming at the error of the collision peak force and the error of the collision time, the correction factor of the wall thickness of the energy absorbing tube is obtained based on the simulation analysis results. Finally, it is verified that the velocity distortion similarity model can accurately predict the dynamic response of the prototype, and reveals the influence of the mass and wall thickness correction factors on the error. [ABSTRACT FROM AUTHOR]

Hierarchical design and gradient design have been shown to improve the crashworthiness of structures. However, fewer studies combine the two. Therefore, this study combines the two to design a novel double-gradient hierarchical hexagonal tube (DGHHT) based on a hexagonal tube (HT). According to the different axial gradients, they are divided into DGHHT-1 and DGHHT-2. The crashworthiness under multiple loads was studied by finite element simulation. Firstly, the reliability of the finite element model is validated by experimental results. Secondly, compared with single-gradient hierarchical hexagonal tubes (SGHHT), DGHHT have better resistance to global bending under multiple loads. When studying mass effects, it was found that both HT and DGHHT had increased peak force and SEA. When HT is designed as DGHHT-2, specific energy absorption (SEA) can be increased by up to 82.74%. Studying the effects of impact angle found that DGHHT-2 has better resistance to global bending than HT as the angle increases. Studying the effect of DGHHT-2 axial gradient distribution found that reasonable distribution of its axial gradient can further improve its ability to resist global bending. Finally, compared with the structures proposed in other studies, DGHHT-2 also has better resistance to global bending at an impact angle of 30°. The double-gradient hierarchical design in this study can provide new design ideas for crashworthiness design. [ABSTRACT FROM AUTHOR]

AbstractTwo strategies are proposed to design new hierarchically reinforced double-square tubes (HRDST). Strategy A: adding triangles from inside to outside in one direction. Strategy B: adding triangles along both the outer and inner quadrilateral directions at the same time. Their crashworthiness analyses are carried out under the conditions of the same wall thickness and the same mass. The results show that the proposed double square tubes, combined with the gradient hierarchical design, can effectively improve the crashworthiness of the structure under both conditions. The improvement of strategy B is more significant than that of strategy A. The energy absorption (EA), specific energy absorption (SEA), and crushing force efficiency (CFE) and initial peak crush force (IPCF) of HRDSTB-3 are improved by 2343.87%, 493.17%, 573.74% and 262.73%, respectively, under the same wall thickness. The EA, SEA, CFE of HRDSTB-3 also increased by 111.23%, 111.23%, and 226.34%, respectively, for the same mass, while the IPCF decreased by 35.27%. The parametric study shows that the effect of wall thickness on structural crashworthiness is significant, but the rate of increase between two adjacent wall thicknesses decreases as the wall thickness increases. The inner and outer edge length ratios (k) also have a substantial effect on structural crashworthiness, with SEA and CFE being 24.42% and 23.47% higher for k = 5/12 compared to k = 8/12 for HRDSTA-3, and 29.24% and 27.55% higher for k = 4/12 compared to k = 8/12 for HRDSTB-3. Finally, comparing HRDSTA-3 and HRDSTB-3 with other square-layered multicellular designs, the results show that the two designs proposed in this paper, combining double square tubes with gradient hierarchies, exhibit better crashworthiness. Compared with MSTL2-2, the SEA of HRDSTA-3 and HRDSTB-3 are 27.98% and 33.01% higher, respectively, and the CFE is 27.86% and 32.96% higher, respectively. [ABSTRACT FROM AUTHOR]

To increase the energy-absorbing capability of frontal collision management systems and improve vehicle crash safety, foam-filled crash boxes should be optimized. On the basis of a double tubular construction, a novel foam-filled crash box with a different design is developed. The energy absorption capacity, initial peak force, and deformation modes of the original and improved crash boxes were examined using impact models. As opposed to the full-filling design, it is demonstrated that the filling design may utilize less foam while increasing specific energy absorption. The stability of continuing deformation after the first buckling is determined by the foam-filled crash box. For the foam-filled crash box, a better-optimized design technique is suggested using the Taguchi method and principal component analysis (PCA). Compression tests are used to validate the design concept. Therefore, the optimal design technique of the crash box is suitable and practical for the crashworthiness design of crash boxes, considering the combined effect of significant indicators for electric vehicles. [ABSTRACT FROM AUTHOR]

When designing the structure of a new vehicle, car manufacturers need to ensure the compliance with strict safety requirements. Aiming to support the engineers in the early phase of this process, we propose a transfer learning framework for crashworthiness. This work explores the possibility to infer knowledge on future situations by exploiting data coming from past development processes. During the early phases of automotive development, assessing the crash safety implies dealing with the challenge of low data availability. Here, the engineers have no hardware test to rely on and can access only few finite element simulations. Under these circumstances, an attractive concept to investigate is the development of a machine learning approach able to learn from the past designs and to transfer the acquired knowledge to the new ones. Transfer learning can serve to this aim. With it, one learns the basic knowledge from a source domain A, and transfers it to a target domain B, characterized by low data availability. Here, we propose a transfer learning framework and apply it to an explicatory industrial crash example. The components produced in the past constitute the source domain; the new component design is the target domain. The proposed methodology can serve as an innovative solution to support car manufacturers in the early phase of vehicle development and thus improve the performance in crashworthiness scenarios. [ABSTRACT FROM AUTHOR]

Inspired by brain corals and cuttlebone, this study employed 3D printing technology to fabricate a novel bio-inspired multilayer sandwich structure based on the Hilbert space-filling curve (named BHSS). The mechanical behavior and deformation process of the BHSS were compared through quasi-static axial crushing experiments and finite element (FE) simulations. The energy absorbing characteristics of the BHSS with different layers were compared through FE simulations, and the results indicated that the 4-layer BHSS displayed superior crashworthiness. Then, parametric studies were conducted to investigate the influence of layer-height gradient and wall-thickness gradient on the energy absorption performance and deformation modes of the BHSS. It was confirmed that the double gradient designs significantly reduced the initial peak force and improved the specific energy absorption of the BHSS. Finally, the multi-objectives optimization based on response surface method and the non-dominated sorting genetic algorithm (NSGA-II) was employed to optimize the geometric parameters of the BHSS, aiming at the optimal configuration for better crashworthiness. Compared to the original design structure, the SEA of the optimized knee point structure was increased by 21.8% and the IPF was reduced by 72.6%. These findings provided valuable guidelines for the brain-coral-inspired design of multilayer sandwich structures with superior energy-absorbing performance. [ABSTRACT FROM AUTHOR]

This article examines the compressive behavior of re-entrant auxetic structures to optimize its energy absorption. The unique properties of auxetic structures have made them popular in various industries, especially for sports equipment. This study aims to create different types of structures using an FDM 3D printer. First, an appropriate raster angle for 3D printing of tensile test samples is examined for PLA and PLA+ materials. Next, three types of structures are constructed using brittle PLA and ductile PLA+ materials, and their energy absorption is compared. These structures are homogeneous auxetic re-entrant (HAR), unilateral graded thickness (UGT), and bilateral graded thickness (BGT). Changing from brittle (PLA) to soft material (PLA+) increases energy absorption in all structures. Likewise, grading the thickness of the structure, especially on BGT, increases energy absorption. Simulation results are validated by modeling the structures in two ways for brittle and ductile materials using Abaqus software. Finally, based on the simulation results, the most appropriate step of the bilateral graded thickness is recognized as 0.8-1-1.2. [ABSTRACT FROM AUTHOR]

This article addresses manufacturing structures made via injection molding from biodegradable materials. The mentioned structures can be successfully used as energy-absorbing liners of all kinds of sports helmets, replacing the previously used expanded polystyrene. This paper is focused on injection technological tests and tensile tests (in quasi-static and dynamic conditions) of several composites based on a PLA matrix with the addition of other biodegradable softening agents, such as PBAT and TPS (the blends were prepared via melt blending using a screw extruder with mass compositions of 50:50, 30:70, and 15:85). Tensile tests showed a positive strain rate sensitivity of the mixtures and a dependence of the increase in the ratio of the dynamic to static yield stress on the increase in the share of the plastic component in the mixture. Technological tests showed that increasing the amount of the plasticizing additive by 35% (from 50% to 85%) results in a decrease in the minimal thickness of the thin-walled element that can be successfully injection molded by about 32% in the case of PLA/PBAT blends (from 0.22 mm to 0.15 mm) and by about 26% in the case of PLA/TPS blends (from 0.23 mm to 0.17 mm). Next, the thin-walled elements (dimensions of 55 × 55 × 20 mm) were manufactured and evaluated using a spring-loaded drop hammer. The 60 J impact energy was tested in accordance with the EN 1078 standard. The dynamic crushing test included checking the influence of the materials' temperature (−20, 0, 20, and 40 °C) and the impact velocity. It was proven that the maximum deflection increases with increasing material temperature and an increase in the share of the plastic component in the mixture. The PLA15PBAT85 blend was selected as the most effective material in terms of its use as an energy-absorbing liner for sport helmets. Johnson–Cook and Cowper–Symonds material plasticizing models were constructed. Their use during dynamic FE simulation provided results that were in good agreement with those of the conducted experiment. [ABSTRACT FROM AUTHOR]

An innovative optimal design framework is developed aiming at enhancing the crashworthiness while ensuring the lightweight design of a hybrid two-dimensional triaxial braided composite (2DTBC) tube, drawing insights from the mesostructure of the composite material. To achieve these goals, we first compile the essential mechanical properties of the 2DTBC using a concentric cylinder model (CCM) and an analytical laminate model. Subsequently, a kriging surrogate model to elucidate the intricate relationship between design variables and macroscopic crashworthiness is developed and validated. Finally, employing multi-objective evolutionary optimization, we identify Pareto optimal solutions, highlighting that reducing the total fiber volume and increasing the glass fiber content in the total fiber volume are crucial for optimal crashworthiness and the lightweight design of the hybrid 2DTBC tube. By integrating advanced predictive modeling techniques with multi-objective evolutionary optimization, the proposed approach not only sheds light on the fundamental principles governing the crashworthiness of hybrid 2DTBC but also provides valuable insights for the design of robust and lightweight composite structures. [ABSTRACT FROM AUTHOR]

The safety of lithium-ion batteries is critical to the safety of battery electric vehicles (BEVs). The purpose of this work is to develop a method to predict battery thermal runaway in full electric vehicle crash simulation. The thermal–electrical–mechanical-coupled finite element analysis is used to model an individual lithium-ion battery cell, a battery module, a battery pack, and a battery electric vehicle with 24 battery modules in a live circuit connection. The lithium-ion battery is modeled using a representative approach, with each internal battery component individually modeled to represent its geometric shape and realistic thermal, mechanical, and electrical properties. A resistance heating solver and Randles circuit model built with a generalized voltage source are used to simulate the electrical behavior of the battery. The thermal simulation of the battery considers the heat capacity and thermal conductivity of different cell components, as well as heat conduction, radiation, and convection at their interfaces. The mechanical property of battery cell and battery module models is validated using spherical punch tests. The electrical property of the battery cell and battery module models is verified against CircuitLab simulation in an external short-circuit test. The simulation results for the battery module's internal resistance are consistent with both experimental data and literature values. The multi-physics coupling phenomenon is demonstrated with a cylindrical compression simulation on the battery module. The multi-physics BEV model with 24 live battery modules is used to simulate the external short-circuit test and the side pole impact test. The simulation run time is less than 24 h. The results demonstrated the feasibility of using a representative battery model and multi-physics analysis to predict battery thermal runaway in full electric vehicle crash analysis. [ABSTRACT FROM AUTHOR]

The crashworthiness of electric vehicles depends on the response of lithium-ion cells to significant deformation and high strain rates. This study thoroughly explores the mechanical behavior due to damage of lithium-ion battery (LIB) cells, focusing on Lithium Nickel Manganese Cobalt Oxide (NMC) and Lithium Iron Phosphate (LFP) types during both quasi-static indentation and dynamic high-velocity penetration tests. Employing a novel approach, a hemispherical indenter addresses gaps in stress–strain data for pouch cells, considering crucial factors like strain rate/load rate and battery cell type. In the finite element method (FEM) analysis, the mechanical response is investigated in two stages. First, a viscoplastic model is developed in Abaqus/Standard to predict the indentation test. Subsequently, a thermomechanical model is formulated to predict the high-speed-impact penetration test. Considering the high plastic strain rate of the LIB cell, adiabatic heating effects are incorporated into this model, eliminating heat conduction between elements. Addressing a notable discrepancy from prior research, this work explores the substantial reduction in force observed when transitioning from a single cell to a stack of two cells. The study aims to unveil the underlying reasons and provide insights into the mechanical behavior of stacked cells. [ABSTRACT FROM AUTHOR]

In this paper, a sinusoidal corrugated filled tube (SCFT) is proposed by filling aluminum foam into a sinusoidal corrugated tube, the finite element model is established using the finite element software Pro/Engineer and Abaqus/Explicit, and the accuracy of the finite element model is verified. Crashworthiness studies under axial impact show that SCFT has better energy absorption (EA) performance than a circular filled tube (CFT) under the same outer tube wall thickness conditions, and the EA and specific EA of SCFT are 1.16 times and 1.12 times that of CFT, respectively; in addition, SCFT has a better interaction effect than CFT under the same outer tube wall thickness. Subsequently, a parametric study of SCFT by amplitude, wavenumber, outer tube wall thickness and aluminum foam density was systematically carried out. The structure studied in this paper can provide a reference for the innovative structural design of filled tubes. [ABSTRACT FROM AUTHOR]

To improve the energy absorption characteristics of thin-walled structures under oblique loads, a new hexagon hierarchical gradient structure (HHGS) was designed in this work, which was inspired by the fractal structure of tree gradient in nature. The crashworthiness of the structure under oblique loads was systematically studied by numerical simulation method. The force-displacement curve of this structure under oblique loads is different from that of conventional thin-walled tubes under axial loads. Crashworthiness comparisons show that gradient structure can significantly reduce initial peak forces and maintain good deformation patterns and energy absorption advantages compared to other structures under oblique loads, at 15° load, the specific energy absorption of the third-order structure was increased by 59.20% at the highest level, at the same time, the initial peak force was reduced by 94.23%. At 30° load, the specific energy absorption of the third-order structure was increased by 32.30% and the initial peak force was reduced by 84.45%. [ABSTRACT FROM AUTHOR]

In this paper, a novel bioinspired hexagonal honeycomb (NBHH) is proposed. Different from the conventional honeycomb (CH), the core wall of the NBHH has a saw-tooth corrugated shape. Firstly, LS-DYNA R11.0 is used to construct a finite element model and conduct experimental verification; then, a comparative analysis is carried out with the CH and the bionic honeycomb sandwich panel (BHSP) with sinusoidal curves, and the proposed NBHH exhibits excellent energy absorption capability under dynamic impact. In particular, compared with the CH and the BHSP with the same wall thickness, the specific energy absorption of the NBHH is 58.60% higher than that of the CH. Compared with the BHSP, the specific energy absorption of the NBHH has increased by 7.23%. Finally, parametric research is carried out on the NBHH. [ABSTRACT FROM AUTHOR]

Multicellular, thin‐walled impact tubes have been intensely studied and used in various engineering fields in recent years due to their lightweight, high performance, ease of application, superior energy absorption, and stable deformation characteristics. In this study, energy absorption, crashworthiness performances, and deformation properties of thin‐walled structures manufactured from polylactic acid (PLA+) and acrylonitrile butadiene styrene (ABS) using fused deposition modeling (FDM) technology were compared under quasi‐static axial compression. Thin‐walled structures consist of multicellular tubes connected by concentric corner‐edge connections with square and hexagonal cross‐sections. Experimental testing outcomes indicate that the energy absorption capacity increases with increasing the number of corners in multicellular structures. The tubes with square wall‐to‐wall (S‐WW) and hexagonal wall‐to‐wall (H‐WW) cross‐sections exhibit superior crashworthiness performance compared to other cross‐sections. Based on the experimental results, the absorbed energy by WW patterned PLA+ square tubes are 19%, 7%, and 46% more than that of wall‐to‐corner (WC), corner‐to‐wall (CW), and corner‐to‐corner (CC) patterned tubes, respectively, while it is 11%, 19%, and 80% more in hexagonal cross‐section tubes, respectively. This study provides an informative reference for easier applicability of multicellular energy‐absorbing structures with 3D‐print and the design of corner‐edge connections of internal connections in multicellular structures. [ABSTRACT FROM AUTHOR]

Inspired by the origami process, a multicellular tube formed by origami folding based on polygons was designed. First, the accuracy of the finite-element model was verified by experiments; then, under the conditions of the same wall thickness, mass, and energy absorption, comparative studies were carried out between multicellular tubes based on polygonal origami folding (MTPOFs), hollow tubes (HTs), and multicellular tubes (MTs). The results showed that regardless of the same wall thickness or the same mass and energy absorption conditions, MTPOFs have advantages over corresponding MTs and HTs. The crushing force efficiency and specific energy absorption of the square MTPOF were 131.45% and 193.57% higher than those of the square HT with the same wall thickness, respectively. Compared with the hexagonal HT, the crushing force efficiency and specific energy absorption of the hexagonal MTPOF increased by 99.02% and 125.01%, respectively. Under the same energy absorption, the crushing force efficiency of the square MTPOF improved by 78.78% and the specific energy absorption improved by 42.05% compared with the square HT. Ultimately, an investigation was conducted into the energy absorption of the structure concerning variations in wall thickness and the ratio of side length to height H/a. As a result, deformation mode diagrams corresponding to different H/a values were obtained. [ABSTRACT FROM AUTHOR]

Hierarchical design and gradient design have proven to be effective in improving the crashworthiness of honeycombs. In this study, a novel graded hierarchical hexagonal honeycomb (GHHH) is proposed by introducing wall thickness variation into the vertex-based hierarchical hexagonal honeycomb (VHHH). The VHHH is obtained by replacing every vertex of the regular hexagonal honeycomb (RHH) with a smaller hexagon. Numerical simulations and theoretical analysis are performed to study the crashworthiness performance of GHHH under the out-of-plane impact. The numerical results show that the specific energy absorption (SEA) of GHHH can be 146.09%, 39.01%, and 50.23% higher than that of RHH, VHHH, and graded hexagonal honeycomb (GHH), respectively, while their peak stresses are nearly the same. In addition, a theoretical model for the plateau stress of GHHH is developed, and the theoretical values show good consistency with numerical results of GHHH with in-extensional mode. The findings of this study provide an effective guideline for the design of honeycombs with enhanced crashworthiness. [ABSTRACT FROM AUTHOR]

Safety is one of the essential and vital factors in the case of the automobile industry. The vehicle has several safety features, like airbags, seat belts, antilock brakes, etc. The car's crash box is one of the crucial safety features that absorb the initial impact. The radiator, intercooler, fender, and hood are expensive parts of a car. A crash box can shield these components. A crash box can reduce the likelihood of the occupants dying or suffering significant injuries. The crash box absorbs kinetic energy from the moving car. This absorption lowers the possibility of occupant injuries and fatalities. Consequently, crash boxes are a crucial life-saving device used in cars. The crash box can be made of different (cross-section) shapes. The different shapes and materials of a crash box are investigated in this study. The study takes into account the square, rectangular, hexagonal, and pentagonal shapes. The configurations are simulated for the energy absorption study under impact load. Crash box analysis focuses on selecting the best material for the crash box and investigating its structural designs. The best material is chosen by applying Analytical Hierarchical Process (AHP). [ABSTRACT FROM AUTHOR]

This study presents a novel variable thickness nested tube consisting of circular tube and origami tube (VTCO) designed to reduce the initial peak crushing force (PCF) under axial loading while maintaining high energy absorption. The core of this design is to achieve progressive and controlled energy absorption and to reduce peak forces as well as accelerations that can lead to passenger injuries. Nested tube structures were fabricated using short carbon fiber‐reinforced nylon composites through 3D printing technology, and quasi‐static axial compression tests were performed. The results show that equal‐thickness nested tubes consisting of circular tubes and origami tubes (ETCO) perform better in terms of energy absorption and deformation stability compared to circular and origami tubes individually. The further improved VTCO reduced the PCF by 53% and significantly improved the crash force efficiency (CFE) by 54%. The VTCO structure was parametrically investigated by means of a validated finite element model and optimized using the Non‐Symmetric Dominance Sorting Genetic Algorithm II (NSGA‐II). The optimization results provide a feasible way to adjust the structural crashworthiness to meet different engineering requirements. This study provides valuable insights into the energy‐absorbing properties of VTCO structures and is an important guide for the application and material development of novel VTCO structures. Highlights: ETCO offers better energy absorption and stability than circular and origami tubes individually.VTCO is superior to ETCO in reducing PCF and increasing CFE.Multi‐objective optimization using NSGA‐II to balance conflicting crashworthiness indicators. [ABSTRACT FROM AUTHOR]

To enhance the out-of-plane mechanical performance, a novel honeycomb with arc-curved edge is proposed. The numerical model is built based on the elastoplastic failure criterion. The impact performance of proposed honeycomb is investigated and revealed. The influence of central angle and thickness on the crashworthiness is researched. The results show that the numerical result is in agreement with that of experimental test. The central angle has great influence on the deformation mode. The global buckling of edge tube is exhibited for the small central angle, and the consistent deformation mode is demonstrated for the central area. With the increasing of central angle, the energy absorption ability is enhanced for the plastic hinge could absorb more impact energy. The more stable deformation mode is exhibited for the larger central angle. The honeycomb with relatively large central angle has the best crashworthiness performance for the balance of energy absorption and structural mass. Compared with traditional honeycomb, the proposed honeycomb could improve the out-of-plane energy absorption characteristics. [ABSTRACT FROM AUTHOR]

By means of material testing, truck testing and numerical simulation, the structural parameters of the shrink tube anti-climb device for high-speed trains were determined. The effects of cone angle, tube thickness, friction coefficient and axial length of the friction cone on the crashworthiness of the shrink tube were studied, and the main causes were analyzed. Using cone angle and tube wall thickness as input variables, and peak crush force, mean crash force and specific energy absorption as crashworthiness indexes, a proxy model was constructed using a radial basis function. The global response surface methodology was adopted to optimize the design of the shrink tube's structural parameters. The results showed that the crashworthiness of the shrink tube was positively correlated with the cone angle, the thickness of the shrink tube and the friction coefficient, and the influence decreased successively, while the influence was negatively correlated with the axial length of the friction cone, which had the least influence. Through the optimized design, the peak force of the shrink tube increased by only 5.41%, while the specific energy absorption increased by 31.03%. Additionally, the mean force was closer to the technical requirements of 600 kN, and the crashworthiness was optimized. [ABSTRACT FROM AUTHOR]

This study extensively characterizes the out‐of‐plane stiffness and energy harvesting capabilities of a newly proposed anti‐trichiral hierarchical auxetic honeycomb structure, both mechanically and deformationally. By introducing a design concept based on the anti‐trichiral honeycomb (ATCH), a structure with superior out‐of‐plane load‐carrying capacity and excellent auxeticity is achieved. To validate the finite element model, compression simulations are conducted. Comparative investigations into the morphing characteristics and energy harvesting performance between the novel structure and the ATCH are performed. Additionally, the influence of various parameters on the comprehensive performance of the novel auxetic structure is explored. It has been found that the angle φ is most sensitive to the auxetic properties, while the ratio k significantly impacts energy absorption. This research advances the design of novel auxetic structures for potential applications in protective engineering. [ABSTRACT FROM AUTHOR]

AbstractDrawing inspiration from nature’s hierarchical organization, we propose a novel bio-inspired hierarchical multi-cellular circular tubes (BHMC) with a fractal structure. Using an experimentally validated LS-DYNA finite element model, we investigated the impact resistance of this structure under axial loading. Numerical analysis was conducted to explore the energy absorption performance of BHMC tubes with varying numbers of branches, fractal orders, and tube masses. The numerical findings indicate that specific energy absorption (SEA) increases with higher numbers of fractal orders. Specifically, the SEA of 2nd order BHMC tubes surpasses that of conventional multicellular circular and single-layer tubes by approximately 35.07% and 17.10%, respectively. Optimal performance is achieved with the proposed structure featuring tree branching (N = 6) and 2nd order fractal characteristics, yielding the highest specific absorption energy across different parameters. These results offer valuable insights for designing multicellular bilayer tubes with superior energy absorption efficiency, providing an effective guideline for structural optimization. [ABSTRACT FROM AUTHOR]

• Collaborative Optimization of Simplified Sections of steel/aluminum vehicle body. • Simplified Section was translated into Complex Section under Constraints of Sectional Mechanical Properties. • Optimization method for complex sections controlled by proportional vectors was established. A multi-level matching transformation and optimization design method for complex sections of thin-walled structures in steel/aluminum vehicle body skeleton was proposed. The problems of lengthy body performance numerical analysis and low optimization efficiency were solved by the rapid collaborative optimization of simplified cross-sections and performance of the body skeleton. A complex cross-sections shape library of thin-walled structures in steel/aluminum body skeleton and formulas for solving section mechanical properties were established, which overcame the difficulty of translating simplified cross-sections of thin-walled structures in steel/aluminum body skeleton to actual complex sections. A precise optimization method for complex cross-sections of thin-walled structure controlled by proportional vectors was established, which solved the defect that it was difficult to precisely control the arbitrary change of complex cross-section shape, and provided a new way for lightweight optimization design of complex cross-sections. The proposed method achieved the rapid collaborative design of steel/aluminum body thin-walled structure with complex cross-sections and body skeleton performance through multi-level progressive cross-section matching transformation and optimization. A body skeleton model with actual complex cross-sections was established, and compared with the initial simplified structure, the weight reduction ratio of the body skeleton was up to 6.9 %, and the performance indicators of the body skeleton fully met the design requirements, which verified the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Lateral corrugated tubes (LCTs) with a sinusoidal cross-section have a wider design space than the ordinary circular tube, which is suitable for design of high performance energy absorbers. To investigate the influence of its structural parameters on crashworthiness, systematic parametric study of the LCTs has been carried out via finite element methods. Results show that LCTs have more deformation modes and more complicated deformations than circular tubes. The amplitude A and the number of corrugations N play a decisive role in the deformation mode and energy absorption. The analysis of different LCTs shows that the specific energy absorption (SEA) of LCTs with (N = 5, A = 3.5 mm) and (N = 7, A = 2.5 mm) increased by 33.68% and 34.97% compared with that of the circular tube, respectively. By changing the basic nominal radius (R0), the SEAs of the LCTs with (N = 6, R0 = 20 mm) and (N = 8, R0 = 18 mm) are 38.33% and 42.66% higher than those of the circular tubes, respectively. The effect of wall thickness on the energy absorption of LCTs was developed. Moreover, the deformation modes of LCTs will be improved by adding ribs inside the structures, significantly increasing its energy absorption. The sinusoidal function is introduced into the structural energy-absorbing design, and structural parameters such as A, N, and R0 can be configured to realize an adjustable and controllable design mechanism. The structural configuration and the design method of LCTs provide a practical reference for the design of energy absorbers. [ABSTRACT FROM AUTHOR]

This experimental study aimed to investigate the effect of strut orientation in various lattice structures that were created using 3D printers on the energy absorption capabilities of the structures. The experiment involved producing three different lattice structures, namely a cube lattice with vertical and horizontal struts, an octet structure with horizontal and 45° angled struts, and a body-centered-cubic (BCC) lattice structure with horizontal, vertical, and 45° angled struts using the FDM method. Nylon filament mixed with chopped carbon fiber was utilized as filament, and each lattice structure was designed to contain three units in the x and y directions and one and three units in the z-direction. The study conducted axial crushing tests on single-layer and threelayer lattices to determine the energy absorption capabilities of the various lattice structures. The octet lattice demonstrated the highest energy absorption in both single-layer and three-layer samples, making it the most efficient sample. In single-layer lattice samples, the cube and octet structures absorbed 77% and 94% more energy than the BCC structure, which absorbed only 12.8 J. However, the cube structure demonstrated the lowest energy absorption in three-layer samples. This was attributed to the buckling behavior seen in the strut of the lattice structure under axial load. The octet structure had the highest specific energy absorption value in both layers, making it the most energy-efficient sample. [ABSTRACT FROM AUTHOR]