Multi-cell Tubes Research Articles

Crashworthiness analysis of novel multi-cell tubes inspired by Chladni patterns

Crashworthiness analysis of novel multi-cell tubes inspired by Chladni patterns

Breaking mechanical performance trade-off in 3D-printed complex lattice-inspired multi-cell tubes under axial compression

It is a long-standing challenge to balance the structural load capacity and toughness in the design of lightweight multi-cell tubes. To tackle this challenge, we provide two kinds of complex lattice-inspired composite multi-cell tubes. The composite multi-cell tubes consist of inner polylactic acid (PLA) complex lattice-inspired multi-cell tubes and outside aluminum tubes. The energy absorption capacity of these multi-cell tubes was evaluated under quasi-static axial compression. The effect of cross-sectional topology and thermal exposure were considered in the experiment. The results show that the integration of PLA tubes within aluminum tubes significantly enhances their energy absorption performance, effectively addressing the limitations posed by the low fracture strain of PLA. The synergistic effect between the aluminum and PLA tubes mitigates the fracture instability and distributes the load more evenly, resulting in improved specific energy absorption (SEA) and mean crushing force (MCF) up to 103.32% and 184.38%, respectively. In these composite tubes, a global self-similar layout can markedly enhance its energy absorption. However, their mechanical properties decrease significantly at 323K compared to room temperature. Overall, this research provides a novel approach to enhancing the mechanical performance of PLA tubes, paving the way for their application in engineering fields requiring lightweight and high-strength structures.

Study on crashworthiness of square frustum lattice structure under in-plane compression load

The direction of load on the component in engineering applications is often uncertain, so the excellent crashworthiness and smooth load transfer of energy-absorbing structures in various directions is of great application value. Square frustum lattice structure (SFLS) was proposed based on the control of cell deformation mode and the improvement of in-plane strength without increasing the overall mass. Compared with multi-cell tubes commonly used in engineering and origami-patterned structure with excellent performance in research, it is found that the SFLS shows high and stable energy absorption capacity with the same structural parameters. The SEA and CFE of SFLS are 1.7 times and 3.5 times of origami structure and multi-cell tube, respectively, and the fluctuation indicator of the force displacement curve of origami structure and multi-cell tube are 1.7 times and 2.7 times of that of SFLS. In-plane quasi-static compression experiment was carried out and the finite element model was verified. The results of parametric analysis and sensitivity show that, compared with the change of cell number and cell height, the crashworthiness of SFLS under in-plane compression was most sensitive to the ratio of side length, in the range of parameters studied, the maximum SEA value of SFLS can reach 79.35 J/g for k value equal to 0.3, while the best indicator of smoothness of force-displacement curve of SFLS is found at k equal to 0.5.

Energy absorption of thin-walled multi-cell tubes with DNA-inspired helical ribs under quasi-static axial loading

Energy absorption of thin-walled multi-cell tubes with DNA-inspired helical ribs under quasi-static axial loading

Crashworthiness design for novel polygonal asymmetric origami tubes

Origami tubes have attracted widespread attention because it is inclined to deform in the complete diamond mode (DM) with a low initial peak force Fmax and high average crushing force Fave. Although conventional origami tubes can improve crashworthiness, there are still many areas that fail to generate traveling plastic hinge lines, and the crashworthiness can be further improved. This paper presents a novel polygonal asymmetric origami tube (PAT) with origami patterns that can trigger more traveling plastic hinge lines compared to those of conventional origami patterns. The theoretical analysis of the deformation mechanism suggests that the PAT can realize hierarchical deformation and avoid stress concentration at sharp corners. The quasi-static experiments and numerical simulations reveal that the novel origami pattern can successfully trigger up to four times more traveling plastic hinge lines than the conventional square box (CSB) under the premise that each plastic hinge line is similar in length. Compared with the CSB, the PAT can deform in DM with a 56.0 % reduction of Fmax and a 59.1 % increase of Fave. Notably, the stableness of load-carrying capacity SLC is 90.2 %, which is 260.8 % higher than the CSB. A series of parametric studies reveal that the dihedral angle ratio α / β and the width-to-thickness ratio c / t of the PAT have a significant effect on crashworthiness. A smaller ratio of α / β and c / t provides the PAT with superior crashworthiness. Comparing the PAT with other types of origami tubes and multi-cell tubes indicates that the PAT also exhibits outstanding crashworthiness. The impact experiments also unveil a significantly enhanced crashworthiness of the PAT. Compared with the CSB, the Fmax decreases by approximately 46.4 %, while the Fave increases by around 92.7 %. The SLC and SEA values for the PAT surpass those of the CSB by about 260.8 % and 93.1 %, respectively. Furthermore, the theoretical analysis for predicting the Fave of the PAT is developed, with a maximum error not exceeding 8.5 %.

A machine learning-based crashworthiness optimization for a novel pine cone-inspired multi-cell tubes under bending

Bionic tubes are of interest in vehicle engineering due to their superior crashworthiness potential. This study proposes a crashworthiness response investigation and machine learning-based multi-objective optimization of pine cone-inspired muti-celled tubes (PCMTs). The base computer PCMT model was correlated using existing experiments, followed by a dynamic response evaluation of different PCMT geometrical and thickness configurations to assess their structural performance. Surrogate models of these PCMTs were then constructed using machine learning algorithms, and their main and interaction effects were analyzed. A non-dominated sorting genetic algorithm II (NSGA-II) approach was employed to perform a multi-objective optimization. The results demonstrate that thickness change had more effect on the initial peak force (IPF) and the mean crushing force (MCF) than the specific energy absorption (SEA). Besides, due to the coupling effect, IPF, MCF and SEA of the optimal design solution of the PCMTs could reach a 36.82 %, 61.66 % and 72.95 % increase than the sum case, suggesting that embedding inner tubes could significantly increase energy absorption with a relative minor IPF increase. Moreover, the MCF and SEA of optimal design gave an average difference of 18.01 % and 5.91 % from the original tubes. PCMTs, therefore, could be used as an ideal energy absorption structure in the vehicle body structures.

On multi-stage deformation and gradual energy absorption of 3D printed multi-cell tubes with varying cross-section

Thin-walled structures are widely used in passive safety systems due to their excellent lightweight and controllable progressive deformation performance. While designing to improve the energy absorption performance of thin-walled structures, it is also crucial to consider reducing the damage received by protected objects during accidental collisions. In this work, stepwise and continuous graded multi-cell tubes with varying cross-sections were proposed based on the fused deposition modeling technique to achieve a gradual energy absorption process. Compression responses and energy absorption characteristics of the graded multi-cell tubes were investigated by quasi-static compression tests. Experimental results showed that the stepwise graded multi-cell tubes produced obvious multi-stage deformation and energy absorption during axial compression. The specific energy absorption presented an upward trend with the increased number of stepwise segments. For the same ranges of cross-section variations, continuous graded multi-cell tubes exhibited more plastic hinges and better energy absorption performance due to the absence of discontinuous interfaces. In addition, continuous graded multi-cell tubes showed continuous folding deformation with the gradually decreasing folding wavelength. Thus, it exhibited a steadily increasing trend in crushing force and realized the gradual energy absorption mode.

Energy Absorption of a Novel Lattice Structure‐Filled Multicell Thin‐Walled Tubes Under Axial and Oblique Loadings

Multicell design and lattice structure as filling material are two effective methods for enhancing the energy absorption performance of thin‐walled tubes. This study combines these two approaches to present a multicell tube with a novel lattice structure and investigates the energy absorption performances of these hybrid multicell tubes under axial (0°) and oblique (10°, 20°, and 30°) impact loading conditions. As filling structure, β‐Ti3Au lattice geometry with varying lattice strut diameters and the number of lattice unit cells are used, while the single and multicell thin‐walled tubes with different tube thicknesses are employed as main absorbing element. In this context, the effects of numbers of lattice unit cells, lattice strut diameter, cell numbers of the tube, and tube thickness on energy absorption performance of hybrid tubes are examined using validated nonlinear finite element models. This investigation unveils that the synergistic interplay between the multicell tubes and lattice structure during deformation significantly elevates the energy absorption performance of the hybrid structure. Notably, the findings demonstrate that multicell hybrid tubes exhibit a remarkable capacity to absorb up to 30.36% more impact energy compared to the aggregate absorption of individual components in hybrid tubes.

Crashworthiness analysis and optimisation of a multi-level bionic multi-cell tube under axial dynamic impact

In this study, a multi-level bionic multi-cell tube (MBMT-n) is proposed, inspired by the horsetail’s cross-sectional structure, and the multi-cell tube shape and distribution characteristics of bamboo vascular bundles. A systematic crashworthiness analysis of MBMT-n under axial dynamic impact was conducted using LS-DYNA. The findings indicate that MBMT-n can enhance crashworthiness while maintaining the same mass. Additionally, the impact of wall thickness and bionic unit cell’s length–width ratio was investigated. Furthermore, a theoretical prediction model for mean crushing force (MCF) was established using the simplified super-folding unit theory. Lastly, to further enhance the structure’s crashworthiness, multi-objective optimisation of MBMT-3 was performed using the NSGA-II algorithm. The several optimal structures were subsequently identified under various peak crushing force (PCF). This study offers a novel approach to the design of energy-absorbing structures.

Experimental and numerical investigation of crashworthiness of multicell metal/CFRP tubes

Metal/CFRP hybrid thin-walled structures combine low-density and high-strength carbon fibre reinforced plastics (CFRP) with low-cost and stable failure form aluminium, which have drawn increasing attention in the transportation industry. A theoretical model was developed to predict the average crushing force of a hybrid multicell under axial compression. The model captures the main energy dissipation mechanism of the hybrid tube under axial compression, and the average crushing force is determined by a quasi-static compression test. The obtained results show that the average crushing force predicted by the theoretical model is in good agreement with the experimental results. However, the geometry size and configuration of multicell thin-walled structures have important effects on crashworthiness. Therefore, it is necessary to study the parametrization of hybrid multicell tubes. First, the simulation model of the multicell tube is established, and quasi-static experiments verify its accuracy. Second, finite element analysis was used to compare the effects of the geometric size of the cell and the multicell structure of different configurations on the energy absorption characteristics. It is clear that with the increase in the thickness of the large aluminium tube, the specific energy absorption (SEA) and crush force efficiency (CFE) both show an upward trend. In addition, with the increase in the ply number of the CFRP tubes, the SEA also shows a minor monotonic increasing trend. Finally, various hybrid tubes with different configurations are designed, and the C-C4-AL tube (the aluminium tube surrounded by four small-size CFRP tubes being placed inside a CFRP tube.) configuration has the most significant energy absorption (EA) and peak crushing force (PCF).

Study on the crashworthiness of multi-cell thin-walled tubes filled with triply periodic minimal surface lattices

To improve energy absorption and efficiency and develop a structure with outstanding energy absorption capability, this study proposed designing multi-cell tubes filled with triply periodic minimal surface (TPMS) lattices. Based on experimental and simulation methods, the crashworthiness of multi-cell tubes filled with three types of TPMS lattices (Diamond, Gyroid, and Primitive) was investigated. Five multi-cell tube structures were fabricated by increasing the thin-walled tube corner units, improving the energy absorption efficiency by 67.98%. The results show that due to the coupling between TPMS lattices and thin-walled tubes, multi-cell tubes filled with TPMS lattices exhibited better crashworthiness performance. The energy absorption of multi-cell tubes filled with Diamond, Gyroid, and Primitive lattices increased sequentially. The energy absorption per unit mass and energy absorption capability were most notably enhanced for the multi-cell tubes filled with Diamond lattice, with energy absorption efficiency 17.24% higher and energy absorption 104.26% greater than empty multi-cell tubes. This inspires crash designs of rail vehicles and automotive fronts.

Design and optimization of bioinspired multicell tubes for energy absorption under axial and oblique loading

Design and optimization of bioinspired multicell tubes for energy absorption under axial and oblique loading

Bayesian optimization of origami multi-cell tubes for energy absorption considering mixed categorical-continuous variables

Multi-cell structures have been widely utilized in energy-absorbing applications for their lightweight and superior mechanical properties. However, they may produce high peak forces that are harmful to occupant safety during a vehicle collision. In addition, the naturally formed folding and global bending modes under axial loads can significantly restrict their energy-absorbing capability. In this study, a novel origami multi-cell structure is proposed to avoid excessive peak loads and at the same time to guide the deformation mode to improve the energy-absorbing capability. Four cross-sectional types of origami multi-cell structures are investigated experimentally and numerically. The results indicated that the web-to-web (W2W) type origami multi-cell structures are most promising for energy absorption, while web-to-corner (W2C) structures yield low peak forces and excellent deformation modes in our study cases. To further exploit the potential of these structures, multi-objective optimization is required to consider the conflicting objectives of maximizing energy-absorbing capability and minimizing the peak force. However, it is challenging for traditional optimization to deal with continuous, integer, and categorical variables simultaneously. Therefore, the Bayesian optimization method based on the Hamming distance is utilized to handle mixed categorical-continuous variables to optimize origami multi-cell tubes. The optimization results indicated that the optimal origami W2C can decrease the peak force by 30 % while keeping a similar level of specific energy-absorbing capability compared with the conventional W2C structure. Moreover, the optimal origami W2C structure can improve the energy absorption by 40 % compared with the origami W2C baseline design.

Energy absorption characteristics of stepped multi-cell columns subjected to transverse loading

Automotive bumper beam is a vital component that shields passenger and vehicle from harm and damage generated by catastrophic collapse. Previous investigations on its bending behavior have largely concentrated on multi-cell tubes with the same length, whereas stepped multi-cell structures have received less attention. In this paper, a novel stepped multi-cell configuration is proposed to improve the energy absorption characteristics of thin-walled structures under transverse loading. The finite element method is employed to analyze the crushing behaviors of the stepped multi-cell tubes. The numerical results reveal that the stepped multi-cell structures (SM2 to SM5) can reduce the initial peak force by 23.44–45.91% while increasing the energy absorption capacity, crush load efficiency, and specific energy absorption by 5.87–29.51, 38.29–139.45, and 5.87–29.51%, respectively, when compared to a conventional square tube (M1). In addition, the effects of wall thickness, section width, load angle, punch radius, and punch shape on the bending behaviors and energy absorption characteristics are examined. The results indicate that these factors have a considerable influence on the deformation features of M1 and SM2, which leads to a significant reduction in their bending energy absorption characteristics. These variables have no influence on the deformation modes of SM3, SM4, and SM5, and they present local indentation deformation with a high energy absorption efficiency. Increasing the number of layers improves the comprehensive performance of stepped multi-cell tubes, with SM5 exhibiting the best energy absorption characteristics under transverse loading.

Data-driven initial peak crushing force prediction of hybrid tubes

Accurately predicting the initial peak crushing force (IPCF) of the CFRP/metal hybrid structure is of great significance for the high-efficiency energy absorption of energy-absorbing elements and ordered deformation of combined energy-absorbing devices. Due to the significant differences in material properties between CFRP and metal and the high complexity of cross-sectional shape, a combined method of machine learning and mechanism analysis is proposed for predicting the IPCF of CFRP/Al hybrid energy-absorbing tube. First, a high-precision finite element model validated by the axial and oblique experiments is conducted to generate the dataset for predictive analysis. Second, a sample space through the design of experiment (DOE) is established for data fitting between structural parameters and IPCF based on traditional response surface model (RSM). It is found that traditional RSM method can successfully predict the IPCF of the single-cell hybrid tube, but cannot effectively predict the IPCF of the multi-cell tube due to the strong coupling effect between inner and outer plates. To address the issue of the lack of accurate correspondence between structural parameters and IPCFs in multi-cell hybrid tube, the indicator of relative density is proposed to characterize complex cross-sectional features. Surprisingly, there is a strong correlation between relative density and IPCF where multi-cell tubes with the same relative density have almost the same IPCF. Third, different artificial neural networks (ANN) are trained by a pre-simulated IPCF database of CFRP/Al hybrid energy-absorbing tube depending on the parameter characterization scheme based on mechanism analysis. In order to enhance the network's performance, the optimal configuration parameters of the neural network, including the number of layers and nodes, are ascertained through a combination of K-fold cross-validation and the Grid Search method. As a result, compared with the traditional RSM and Kriging model, the IPCF of CFRP/Al hybrid energy-absorbing tube can be predicted in small samples with high accuracy using the optimal ANN model. Finally, Through the comparative analysis of the IPCF of hybrid tubes with reported multi-cell configurations, it is found that the prediction model proposed in this paper has good generalization ability, which can be used to predict more complex types of multi-cell tube configurations. The present study offers important suggestions for the overall control of multi-materials hybrid energy-absorbing tube and the ordered deformation of combined energy-absorbing devices.

Crashworthiness analysis of variable thickness CFRP/Al hybrid multi-cell tube

In order to fully utilize the energy absorption potential of hybrid structure composed of multiple materials, a variable thickness Carbon Fiber Reinforced Plastic/ aluminum (CFRP/Al) hybrid multi-cell tube is proposed, with a focus on the design strategies of variable thickness filament winding and multi-cell layout. First, based on the validated finite element (FE) model, a comparative study of different tube configurations is implemented to clarify the advantages and disadvantages of multi-cell hybrid tube. By analyzing the energy absorption contribution of two component materials and local structures, the bending instability mechanism of multi-cell hybrid tube at large angles is revealed to emphasize the necessity of variable thickness filament winding. It is found that multi-cell Al tube is the key factor to induce structural instability, and CFRP with positive gradient thickness distribution is beneficial to restrain the bending instability of hybrid multi-cell tube. Second, in order to better describe the influence mechanism of the design parameters, two comprehensive crashworthiness performance indicators for multi-angle compression conditions are proposed, namely comprehensive specific energy absorption and energy absorption stability. Then, a detailed parametric study is performed to explore the influence mechanism of the variable thickness winding parameters and multi-cell cross-section parameters on the comprehensive energy absorption capacity of the hybrid tube under multi-angle compression conditions. Finally, an application recommendation for the variable thickness CFRP/Al hybrid multi-cell tube is given to provide a reasonable design strategy. Furthermore, a comparative analysis of crashworthiness between the suggested CFRP/Al hybrid tube and reported typical energy-absorbing structures is carried out to reveal the superiority of the variable thickness CFRP/Al hybrid multi-cell tube in the energy absorption stability. This research provides valuable guidelines and suggestions for the crashworthiness design of multi-material hybrid structures facing complex loading conditions.

Energy absorption and topology optimization of self-similar inspired multi-cell square tubes

Due to their low cost and lightweight properties, multi-cell square tubes have been widely used in impact protection as energy absorbers. In this study, two kinds of multi-cell square tubes were constructed according to the local self-similar and global self-similar layout strategies. The experiments and numerical simulations were conducted to investigate their quasi-static compression deformation and energy absorption. The results demonstrated that self-similar layout strategies can significantly enhance the crashworthiness of multi-cell square tubes, and the global self-similar layout appears to be more effective at energy absorption. A simplified theoretical model for the mean crushing force (MCF) was developed for its constituent elements of the proposed square tubes. Furthermore, the COPRAS method and the non-dominated sorting genetic algorithm II (NSGA-II) were employed for optimal structure selection and multi-objective optimization. The results showed that the 2nd-order global self-similar multi-cell square tube (MSTG1-2) had prominent crashworthiness compared with some typical self-similar square tubes. The current optimization and topology design strategies can be used in other polygonal multi-cell tubes, which provides an effective guide for enhancing the crashworthiness of these multi-cell tubes.

An investigation on the energy absorption capability of aluminum foam-filled multi-cell tubes

An investigation on the energy absorption capability of aluminum foam-filled multi-cell tubes

Integrated design and additive manufacturing of lattice-filled multi-cell tubes

In this paper, 3D printed lattice-filled multi-cell tubes, fabricated using chopped carbon-fiber-reinforced polyamide, were proposed to modify the deformation modes and improve the crashworthiness. Compression responses and energy absorption characteristics of the multi-cell tubes were investigated by quasi-static compression tests. The deformation and synergistic effect mechanisms of lattice-filled tubes were studied by observing the longitudinal sections of specimens. It was found that filling the lattice into multi-cell tubes exhibited an increase in the number of folds. When the lattice-filled tubes were fabricated integrally, multi-cell tubes changed from an asymmetrical to a symmetrical folding deformation mode due to the stronger and symmetrical interactions from the internal-filled lattice. Under the influence of the synergistic effect, the total energy absorption of the lattice-filled tubes with two different combination strategies presented increases of 55.6% and 83.8% compared with the sum of the empty multi-cell tube and pure lattice. In addition, a theoretical analysis for the mean crushing force of composite lattice-filled tubes was conducted based on simplified super folding element (SSFE) theory and bending deformation mechanism of the struts. The theoretical results were in good agreement with experimental studies and could be extended for lattice-filled tubes with other different filling configurations.

Energy-absorbing characteristics of hollow-cylindrical hierarchical honeycomb composite tubes under conditions of dynamic crushing

This paper presents an experimental and numerical study on the energy-absorbing characteristics of Biomimetic Multi-Cell Tubes (BMCTs), these being hollow-cylindrical-joint hierarchical honeycomb composite tubes inspired by the microstructural features of a beetle's forewing and geometrical features found in a spider's web. The BMCTs were fabricated using carbon fiber composites in optimized multi-tiered configurations. Low velocity crushing tests were conducted to characterize the load-displacement response, crashworthiness mechanisms, and energy absorption capacity of the BMCTs based on specific layer stacking sequences (LS). Additionally, the dynamic response of the BMCTs was modeled using the finite element analysis techniques.The predicted load-displacement relationships and failure modes show good agreement with the experimental results. Dynamic effects in the energy absorption characteristics of the tubes were evaluated. It is shown that the dynamic energy-absorbing capability of the BMCT-LS2 structure (Wall [±45/±30/±15]s Cylinder [±45/±30/±15/06]) is 6.5% higher than its quasi-static counterpart. In contrast, the SEA of BMCT-LS1 (Wall [+453/-453]s Cylinder [+453/-453/06]) is almost the same under both loading regimes. Finally, the quasi-static SEA of the plain circular tube is 13.8% lower than its dynamic counterpart. However, the SEA values of both BMCT-LS1 and BMCT-LS2 structures are 65% and 173% higher than the plain circular tubes, respectively.