Crashworthiness Characteristics Research Articles

Enhancing crashworthiness characteristics of modified hexagonal honeycomb structural panels through stretching and bending of ribs

The effects of stretching and bending of concave, convex, and horizontal ribs on the energy absorption characteristics of modified hexagonal honeycomb structural panels are investigated under in-plane quasi-static compression loading conditions. In this regard, five hierarchical modified structural panel configurations were fabricated using polylactic acid material (PLA) via a fused filament 3D printer, ensuring uniform wall thickness in the 1.5–2 mm range. The panels included the regular hexagonal panel (RHP), regular hexagonal panel with concave rib (RHCP), regular hexagonal panel with convex rib (RHXP), regular hexagonal panel with concave and horizontal ribs (RHCRP), and regular hexagonal panel with convex and horizontal ribs (RHXRP). In-plane quasi-static compressive loading tests were conducted to analyze crush resistance characteristics, and buckling modes of the modified honeycomb panels were examined through experimental and finite element analysis procedures. The result indicates that the specific energy absorption capacity (SEA) of RHXRP is increasing significantly compared to the SEA capacity of other categories of the structures. The changes in failure modes and increased crush energy absorption characteristics of modified RHP with the introduction of concave, convex, and horizontal ribs are elaborated.

Crushing characteristics and multi-objective optimisation of a novel bionic frog leg tube

Recently, the demands for structural impact protection in automobile, train, aerospace and other fields have become increasingly intense, and the bionic energy absorption structures have attracted widespread attention for their excellent structural properties and crushing characteristics. In this study, inspired by the great impact resistance of the frog legs, a novel bionic frog leg tube was proposed and investigated by numerical simulation and parametric study. Firstly, according to the structural forms of the legs for frogs, humans and pigs, three types of bionic leg tubes were designed, and the energy absorption characteristics of these tubes subjected to axial loading were investigated, it was found that the peaking crushing force ( PCF ) and undulation of load-carrying capacity ( ULC ) seem to have a strong relationship with the jumping ability for animals, lower PCF and ULC could decrease the injury transmitted to the body. Then, the parametric studies were conducted to investigate the effects of structural parameters on the crushing behaviour of the bionic tubes, the results indicated that a bionic frog leg tube with smaller L 1 tends to present the concertina deformation mode, and a larger L 1 will lead to the diamond mode or mixed mode. Lastly, the multi-objective optimisation of the bionic frog leg tube was carried out to simultaneously improve specific energy absorption ( SEA ), crushing force efficiency ( CFE ), and reduce ULC , based on the NSGA-II algorithm. The optimal configuration of the structural parameters of the bionic tube was obtained, and the bionic tubes present better crashworthiness characteristics than initial structures under the axial loading. The findings of this study provide new insights into the transformation of natural biological inspiration into engineering applications for protective structures.

Optimization of the octagonal origami tube energy absorption using the artificial neural network and heuristic method

This article presents a hybrid optimization approach for improving the crashworthiness characteristics of thin-walled metallic tubes using a unique multilayered origami pattern. In the quasi-static axial loading condition, a total of 120 thin-walled tube samples were simulated using the full factorial design method to assess the impact of geometric parameters on their crashworthiness behavior, including the dihedral angle, module number, and outer layer height. Additionally, based on the input parameters, an artificial neural network was implemented to estimate the mechanical response of the tubes. Then, to determine the ideal design parameters, a hybrid multi-objective optimization approach was used. The Technique for Order of Preference by Similarity to Ideal Solution technique was utilized to extract the optimal design to balance the objectives of energy absorption and initial peak force. The specific energy absorption of the optimal tube was discovered to be 68% higher than that of the base tube. The simulation results demonstrate that the proposed multilayered origami pattern provides a unique structure that improves the crashworthiness properties of the thin-walled metallic tubes.

Failure modes and energy absorption mechanism of CFRP thin-walled square tubes filled with gradient foam aluminum under axial compression

Carbon Fiber Reinforced Plastic (CFRP) thin-walled square tube filled with gradient foam aluminum represents a novel component known for its exceptional energy absorption capabilities. This paper investigates the failure modes and energy absorption mechanisms of CFRP thin-walled square tubes filled with gradient foam aluminum using a combination of numerical simulations and quasi-static axial compression tests. The influences of some factors, including lay-up angles, lay-up sequences, and lay-up thicknesses have been analyzed. Additionally, the impact of the gradient foam aluminum filler on the crashworthiness characteristics has been scrutinized. The results reveal that the samples with lay-up angles below 45° showed a failure mode characterized by layer bundle buckling during axial compression. Conversely, the samples with lay-up angles exceeding 45° exhibited lateral shear failure during axial compression, with the latter demonstrating notably higher energy absorption efficiency. Increasing the proportion of circumferential angle and setting the circumferential angle on both the inner and outer sides of the axial lay-up, the energy-absorption capacity of the filled CFRP tubes under axial compression can be improved. This study demonstrates the potential of CFRP tubes filled with gradient foam aluminum to be used as energy absorbers.

Dynamic response of bionic non-convex tubes with proportional distribution of bulkhead

Non-convex tubes that have superior energy absorption potential may expand and deform unstable during impact, limiting energy absorption. The bamboo node can strengthen bamboo by resisting expansion. Therefore, bulkhead proportional distribution of bionic non-convex (BPDBN) tubes, an integrator of them, may present more efficient energy absorption performance. This research proposed to investigate the effect of geometrical parameters on the crashworthiness characteristics of BPDBN tubes. The position of bulkheads was assumed to vary according to the positive proportional function primarily determined by proportional coefficient k. The dynamic response was evaluated by the initial peak force (IPF), specific energy absorption (SEA), and crush force efficiency (CFE). Multi-objective optimization method was utilized to further improve the energy absorption performance. The optimal design lowered the IPF (34.00%), increased the SEA (37.16%) and the CFE (42.95%). This paper emphasizes that optimizing the geometrical parameters and the bulkhead distance proportion can significantly improve the crashworthiness performance of BPDBN tubes.

Crash Box Impact Energy Absorption

Abstract: Crashworthiness parameters like internal energy absorption and crush force efficiency are the key constants in evaluating the component crashworthiness and its safety in the design of automotive structures for crashworthiness, there is an immense requirement for null strain sub modules that provide a rigid room of survival area for the occupants and deformable sub modules. Which can dematerialize the kinetic energy effectively? The front crash box of an automotive car is one of the most important deformable components which dissipate kinetic energy while frontal crash, which is the most persistent crash situation, affects the entire automotive structural behavior. In this research, quasi-static axial loading response and crashworthiness characteristics of empty hollow tube have been investigated through experimental and numerical simulations. The axial quasi-static loading was executed at a feed rate to evaluate the crashworthiness constants of each sample against quasi-static loading. The supremacy of feed rate empty hallow structures were pursued. The numerical simulation of quasi-static test was performed in accordance with explicit finite element algorithm of LS-DYNA in order to investigate and justify the crashworthiness of each variety of specimens with experimental results.

Energy absorption capability of laterally loaded glass/epoxy tubular components containing halloysite nanotubes

The crashworthiness capability of laterally loaded glass/epoxy (GFRE) tubular components containing halloysite nanotubes (HNTs) was explored in this article. GFRE components filled with 0, 1, 2, 3, and 4 weight percent (wt.%) of HNTs were created using wet-wrapping by hand lay-up technique. For the laterally loaded tubes, the crushing load and the energy absorption versus displacement responses were presented. In addition, distortion histories were tracked. The crashworthiness analysis was carried out by evaluating different indicators, i.e., initial crush load [Formula: see text], average crush load ([Formula: see text]), crush load efficiency (CFE), energy absorption (U), and specific absorbed energy (SEA). Two parameters of the Weibull distribution were employed to assess the experimental findings statistically. In addition, mathematical regression models were built to predict the energy absorption indicators. Experimental results demonstrated that an unfilled tube demonstrated the largest CFE of 1.84, while the maximum [Formula: see text] was demonstrated by a tube filled with 2 wt.% of HNTs with a value of 3.70 kN. Additionally, the tube filled with 4 wt.% of HNTs represents the extremes [Formula: see text], U, and SEA with values of 4.26 kN, 128.82 J, and 3.84 J/g, respectively. Due to their improved crashworthiness characteristics, GFRE filled with 4 wt.% of HNTs is suitable for use as a crashworthy device in automobiles.

Multi-objective optimization of foam-filled tubes to enhance the crashworthiness characteristics under impact loading

Multi-objective optimization of foam-filled tubes to enhance the crashworthiness characteristics under impact loading

Buckling assessment of GFRP and carbon fiber-reinforced plastic filament-wound tubes using an acoustic emission-based methodology

The aim of this research is to investigate the failure mechanisms of the filament-wound composite tubes under axial compressional loading by using an acoustic emission approach. First, the mechanical properties of ±45°C composite tubes were obtained experimentally. Then, failure due to the buckling phenomenon and crashworthiness characteristics were studied utilizing numerical simulation and experimental methods. Tubes were next simulated in ABAQUS software, and a continuum damage mechanics model was implemented in a progressive framework to assess the failure modes. From the macroscale view, results showed that the damage behavior of composite tubes turned out to be dominated by local buckling followed by a post-buckling field, which is generated by longitudinal cracks along the winding direction. On the micro-scale, the acoustic emission-based procedure based on the wavelet packet transform method was adopted. The hierarchical modeled assessment resulted in the identity of four clusters of AE signals. In GFRP tubes, the fiber breakage and fiber/matrix separation could mostly control the higher percentage of damage and cause to increase the energy absorption. Finally, by comparing the results obtained from micro and macro scales, the local buckling failure mode was attributed to the low content of fiber/matrix debonding in the structure.

Experimental and numerical investigation on crashworthiness of composite reinforced auxetic cellular tubes

This study aims to investigate the crashworthiness properties of thin-walled foam-filled Auxetic metal/composite cellular tubes under quasi-static and low-velocity impact axial loading. The specimens were fabricated using thin-walled steel tubes and Glass Fiber Reinforced Composite (GFRC) laminates. The crashworthiness characteristics including peak load, absorbed energy, specific absorbed energy, and failure mechanisms of the hybrid structures were studied and compared with individual hollow section and foam-filled Auxetic tubes. In addition, detailed FE simulations were performed using LS-DYNA software, which was verified by the experiments.

Visco-Elastic Honeycomb Structures with Increased Energy Absorption and Shape Recovery Performance Using Buckling Initiators.

Energy-absorbing materials have extensive applications in aerospace and automotive applications. Research has shown buckling initiators, or triggers, in energy-absorbing tubular structures increase the energy absorbed by encouraging the side panels to fold when loaded out of plane in compression conditions. Additively manufactured TPE honeycombs were designed in this study to include these buckling initiators, which introduced a slight decrease in initial weight, as well as initial stress concentrations, while improving crashworthiness characteristics. The samples with buckling initiators (1BI) showed an increase in crush efficiency when directly compared to their no buckling initiator (0BI) counterparts. The 1BI samples maintained an increased crush efficiency regardless of the strain rate used. The samples with 1BI were able to better equilibrate the peak stress with the plateau stress. These honeycomb samples were found to maintain their crush efficiency, even after multiple rounds of compression testing. The quasi-static 0BI samples experienced a 23.4% decrease in the peak stress after multiple rounds of compression testing, while the 1BI samples saw approximately a 23.0% decrease. The 1BI samples averaged a decrease in crush efficiency of 0.5%, while the 0BI samples saw a decrease in crush efficiency of 5%. As the strain rate increased, the crush efficiency for the 1BI samples showed an increase in performance, with a smaller degradation in crush efficiency over multiple uses. Visco-elastic honeycomb with buckling initiators has a higher energy absorption than samples with no buckling initiators when exposed to multiple impact cycles.

Bending Performance and Crashworthiness Characteristics of Sandwich Beams with New Auxetic Core

Structures with enhanced mechanical properties and crashworthiness are competing materials in the transport industry to reduce structural weight, and auxetic materials are the ideal choice. Auxetic metamaterials are the class of cellular structures designed to possess negative Poisson's ratio. The current study evaluates newly developed re‐entrant diamond auxetic metamaterial's in‐plane and out‐of‐plane three‐point bending performance. A series of experimental and numerical studies are performed to assess the quasistatic performance and crashworthiness characteristics of 3D‐printed re‐entrant diamond auxetic core and sandwich panels. The results are compared with regular re‐entrant panels of the same unit cell size. The deformation and failure mechanism of both auxetic structures, core and sandwich, are discussed. Real‐time displacement contours on the specimen surface are visualized using advanced image processing and finite‐element methods. The new re‐entrant diamond auxetic members outperformed energy absorption characteristics in in‐plane and out‐plane directions. Compared to the counterpart, the new metamaterial has improved 88.33% and 29.24% in‐plane energy absorption as a core and sandwich, respectively. 13.51% and 13.35% increments in energy absorption as a core and sandwich are observed for re‐entrant diamond structures compared to the regular re‐entrant system in the out‐of‐plane direction.

Energy absorption investigation of SFRFC-filled double circular tubes under quasi-static compression and low velocity impact loading

The filled thin-walled tube (FTT) is a common energy absorption device, which consists of two important parts: filled materials and thin-walled tubes. According to existing researches, the filled materials significantly influence the mechanical properties of FTTs, especially the energy absorption capacity. In this study, a novel design of FTTs is proposed and studied, which adopts the double aluminum (Al) pipe and is filled with the steel fiber reinforced foamed concrete (SFRFC). Firstly, specimens with different steel fiber contents of 0, 0.5, 1, 1.5, and 2% are prepared and tested under quasi-static compression, and the influence of dynamic velocity (4.4, 6.2and 7.6 m/s) are investigated; then, the numerical modeling is conducted to study the influence of structural parameters on the energy absorption properties of the proposed SFRFC FTTs under quasi-static compression loadings. Results show that an appropriate content of steel fiber can prolong the stress platform under quasi-static compression loadings, and stabilize the fluctuation during dynamic plastic buckling. The thickness、diameter、aspect ratio of SFRFC FTTS have a significant effect on the SEA and CFE, especially the thickness of the inner tubes, which means the geometry parameters obviously affect the crashworthiness characteristics of SFRFC FTTs. According to the results of this research, it can be concluded that SFRFC is an excellent and potential energy adsorption filled material for FTTs, which can obviously improve the mechanical properties of filled thin-walled tubes under quasi-static and low velocity impact loadings.

Quasi-static compressive performance of 3D printed polymer composite cellular cubic structures-An experimental study

Light weight cellular structures have gained extensive attention in the impact energy absorption applications owing to their superior specific strength and excellent crashworthiness characteristics. The main objective of the present research work is to utilize this benefit to tailor and to improve the structural design and material type of cellular structures for crashworthiness applications. Cubic structures with four different types of design patterns such as concave, convex, hyperbola, and hexagon were proposed and fabricated through three-dimensional (3D) printing technique. Four polymeric filament materials such as Poly lactic acid (PLA), Acrylonitrile butadiene styrene (ABS), PLA mixed carbon fiber (PLA/CF), and Polyethylene terephthalate glycol (PETG), mixed carbon fiber (PETG/CF) were utilized. Accordingly, the compression tests were performed on the fabricated cellular cubic structures under quasi-static loading to examine the effect of design pattern, and material types on the compressive behavior and energy absorbing characteristics. The results revealed that the convex design pattern of 3D printed PETG/CF cubic structure showed the significant energy absorbing characteristics compared to the other three design patterns. It is emphasized that the proposed 3D printed cubic cellular structures have great prospective to substitute the traditional energy absorbing structures in automotive vehicles and high speed trains.

Investigation of the effect of friction force on the energy absorption characteristics of thin-walled structures loaded with axial impact force

In recent years, there has been a significant increase in studies aimed at enhancing the energy absorption capabilities of thin-walled structures used in vehicles. These studies aim to mitigate the adverse effects of shock waves released during crashes by incorporating recesses that trigger folding on the walls of crash boxes, thereby increasing energy absorption. This particular study investigates the energy absorption and crushing behaviors of interpenetrating thin-walled structures under axial crushing conditions. Two different configurations were modeled to determine the contribution of friction force in dampening impacts in thin-walled structures. One configuration exhibited classical folding, while the other initiated folding after interpenetration upon the application of an axial impact load. The interpenetrating structures generate friction forces through recesses and protrusions on the surface of the crash box to provide energy absorption. The simulations were conducted using the finite element method (FEM) in a non-linear explicit dynamic collision scenario. The crash scenarios for both configurations were analyzed under identical conditions using two different materials (DP-600 and DP-800) and three different thicknesses (1.2 mm, 1.4 mm, and 1.5 mm). The dynamic crash simulations were compared based on Specific Energy Absorption (SEA), Total Energy (ET), Peak Crush Force (PK), Crush Force Efficiency (CE), and Mean Crushing Force (FM) values to examine the effects of friction force on energy absorption capabilities and crushing behaviors of the crash boxes. The analysis results demonstrated that friction force and energy absorption play a positive role in the crashworthiness characteristics of thin-walled structures.

Energy absorption characteristics of a super hexagonal honeycomb under out-of-plane crushing

Designing innovative honeycomb materials with improved energy absorption capacity is a long-term pursuit to provide adequate impact protection for crucial structural components. The edge-based design has been regarded as an effective strategy to enhance the mechanical properties and energy absorption of honeycomb materials. This paper proposes a novel super hexagonal honeycomb (SHH) structure to pursue better energy absorption capacities. Its geometry is derived from the outline of a hexagonal honeycomb. The crushing performance of the SHH is investigated based on the out-of-plane compression experiments, and an explicit finite element model is established to explore the crashworthiness characteristics of the structure. Furthermore, a theoretical model based on the simplified super folding element (SSFE) method is established to predict the mean crushing force during the crushing process. The comparison with the experimental and numerical results verifies its accuracy. Besides, the crushing mechanisms and collapse modes of the constitutive Y and V elements in the SHH are discussed. The parametric analysis of the crashworthiness of the SHH is conducted in terms of the cell-wall length ratio, sub-corner angle and hierarchy. The results reveal that the crashworthiness of SHH is much superior to traditional hexagonal honeycomb and presents 106%, 62%, 104% and 162% improvement in the mean crushing force, crushing force efficiency, specific energy absorption and volumetric energy absorption, respectively. This work can inspire future research on lightweight edge-based honeycombs with excellent energy absorption capacity.

Improvements in the lateral crushing behavior of syntactic foam‐filled glass fiber reinforced polymer tubes by the addition of straight and helical multiwalled carbon nanotubes

AbstractTo diminish the brittleness of glass fiber reinforced polymer tubes and syntactic foams, a novel composite tube filled with syntactic foam was proposed, in which thin‐walled tubes were reinforced by ribs and the syntactic foam core reinforced with multiwalled carbon nanotubes (MWCNTs). The influence of the ribs and the type and content of MWCNTs on the lateral crashworthy characteristics of composite tubes was investigated. Crushing experimental results indicated that the ribs contributed to improving the crashworthy performance for both hollow and foam‐filled tubes. The effect of the ribs on the energy absorption was more pronounced for the hollow tubes. Incorporation of straight or helical MWCNTs lead to improvement of the crush resistance and energy absorption for foam‐filled tubes. With the same MWCNT content, the peak load and absorbed energy of specimens with helical MWCNTs were nearly 14% and 13% higher than those of specimens with straight MWCNTs, respectively. Furthermore, analytical models were proposed to predict the load–displacement responses for foam‐filled tubes in the linear‐elastic, postcrushing, and foam‐compaction stages. The predicted results agreed well with experimental results. The resulting composite tubes are potential light‐weighted and crashworthy structures, which could be applied as collapsible energy absorbers in engineering fields.

Quasi‐static compression behavior and crashworthiness of GLARE laminate conical frustum with progressive circular and square cut‐outs

AbstractThe design of structures using advanced composite materials such as fiber metal laminate requires an in‐depth understanding of their deformation behavior and response to the discontinuities in the structures. In the present study, a GLARE kind of fiber metal laminate in 2/1 configuration was fabricated in the form of conical frustum. Three cut‐outs of two different shapes such as circular and square were intentionally made at the center of the frustum at an angular distance of 120°. The quasi‐static compression test was conducted to determine the crashworthiness characteristics of laminate frustums with cut‐out and the results were compared with perfect frustum. The study showed that the laminate with cut‐out undergone for inward buckling near the discontinuities. Apart from that, the delamination and outward buckling were noted in the edges of the cut‐outs. The energy absorption of laminate frustum with circular cut‐outs was observed to be better than square cut‐outs. The performance of laminate frustums with cut‐outs was ranked using Technique for Order Preference by Similarity to an Ideal Solution technique. A finite element analysis was carried out to simulate the deformation behavior of laminate frustum with cut‐outs and the numerical results of deformation mode closely represented the experimental results.

Study of effect of provision of cut-outs on axial collapse behaviour of circular aluminium tubes

Geometrical modification of thin-walled tubular structure is one of the innovative ways in the development for vehicle safety design. This research is developed in accordance with the need of investigation on behaviour of tubular structures with geometrical modifications like cut-outs under dynamic loading technique. Diamond and elliptical cut-out shapes are provided in multiple number arranged circumferentially in a single row on a tube surface. Tubes with cut-outs are loaded axially at three different velocities, corresponding to three different strain rates. Energy absorption characteristics like energy efficiency, specific energy absorption, peak collapse force, mean collapse force and efficiency of peak force reduction at the initiation of tube deformation are calculated and compared using finite element (FE) based ABAQUS/Explicit® software. Split-Hopkinson Pressure Bar (SHPB) is modelled in the FE software to understand the material behaviour under high strain dynamic loading. Johnson-Cook material model parameters are incorporated in the study to understand the strain rate sensitive behaviour of aluminium alloy material. Results revealed that providing diamond and elliptical cut-outs on tube is much efficient than providing circular cut-outs on tube, in terms of percentage peak load reduction as well as energy efficiency of structure. It was observed that number of cut-outs influences the polygonal deformation pattern of tube with cut-outs. Overall study significantly helps to achieve the aim of improving vehicle crashworthiness characteristics by implementing cut-outs in a crash frame.

A machine learning based optimisation method to evaluate the crushing behaviours of square tubes with rectangular-hole-type initiators

Rectangular-hole-type crush initiators have attracted much attention due to their exceptional advantages in improving crashworthiness performance. Unfortunately, undesired deformation buckling modes, i.e. bifurcation buckling, can occur and challenge optimisation processes. This paper aims remedies to this limitation and proposes a machine learning based optimisation method that removes these undesired deformation modes to effectively evaluate the effect of initiators’ parameters in improving crush response. First, finite element models of square tubes with different numbers and positions of initiators were built and computed. Second, the complex proportional assessment (COPRAS) method was adopted to rank the crashworthiness characteristics. The results demonstrated that square tubes with two sets of four corner holes along the axial direction were the best choice. Finally, the optimisation method based on machine learning was employed to evaluate the influence of the initiator’s size on the crushing behaviours for minimizing the initial peak force (IPF), maximizing the energy absorption (EA), and crushing force efficiency (CFE). The results illustrated that the IPF of the optimised design Pareto front upper limit is about 21.94% lower, with 0.08% and 36.67% higher EA and CFE, respectively, than those of the best choice observed from COPRAS. This study highlights the ability of the proposed machine learning based optimisation method to improve crashworthiness performance.