Bionic Tubes Research Articles

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.

Design and mechanical properties analysis of bionic tube based on cattle horn structure

Composite tubes are widely adopted in engineering protections owning to desirable passive energy absorption. With the aim of enhancing energy absorption and making full use of structural materials, a novel tube inspired by the structure of cattle horn has been designed. It consisted of a shell composed of nested tubes and a core composed of evenly distributed tubes, which are connected by beams. The energy absorption properties of bionic tube, six-cell tube, four-cell tube and circular tube were compared by numerical models verified by axial compression. The factors affecting mechanical responses and energy absorption capacities of bionic tube were analysed. Compared to the six-cell tube, the bionic tube exhibited a 104.91% increase in peak load, a 239.51% increase in mean load and an 83.39% increase in specific energy absorption. Under the premise of ensuring the energy absorption, mean load and crushing force efficiency, the mass and peak load can be controlled by limiting the wall thickness and height of core. The proposed bionic tube had the potential to be applied in the automobile and aerospace industry.

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.

Crashworthiness analysis of novel cactus-inspired multi-cell structures under axial crushing

This study introduces an innovative cactus-inspired bionic tube (CBT) designed for enhanced energy absorption, drawing inspiration from the ribbed structure of cacti. Validation is achieved through quasi-static crushing experiments, confirming the numerical model's accuracy. Numerical simulations investigate critical factors, including structural mass, wall thickness, loading velocity, and cross-sectional configuration, revealing that proper cross-section design can boost the specific energy absorption (SEA) of the original CBT by 15.84 %. Additionally, a theoretical model is developed to forecast the mean crushing force of CBTs. Comparative analysis demonstrates the superior crashworthiness of CBTs over contemporary bionic and widely adopted multicell structures with the same mass, achieving a remarkable SEA of 11.44 J/g—exceeding maximum and minimum SEA values of these structures by 28.3 % and 127.9 %, respectively. This research significantly contributes to advancing the development of high-performance bionic energy-absorbing structures for crash applications.

High‐Temperature Creep Behavior of Selective‐Laser‐Melting‐Fabricated Lattice Structures Inspired from Euplectella Aspergillum

In this study, the lattice‐like arrangement of Euplectella aspergillum is used to derive bionic grid‐stiffened structures in the form of thin tubes. The bionic tubes are 3D printed with AlSi10Mg alloy using a selective laser melting process. High‐temperature creep behavior at 250 °C and stress (0.3–0.7) times yield strength of the tubes is studied under uniaxial constant compressive load. The effect of the stress level, temperature, and tube design on the creep performance and deformation behavior is studied. The creep performance of bioinspired tubes is compared with honeycomb lattice tubes. In the results, the dependence of creep life and creep rate on the design of the bionic tubes is shown. E. aspergillum–based thin tubes show higher creep life and lower creep rate as compared to honeycomb‐based tubes at all stress levels. Also, the creep curves of lattice structures based thin tubes are different than the solid material, especially in the primary and tertiary regions. The fractography analysis shows higher creep life in E. aspergillum–inspired thin tubes is due to the improvement in ductility at high temperature. The stress exponent value in the Mukherjee–Bird–Dorn equation shows that the mechanism of creep is diffusion. Herein, in the results, it is shown that the bioinspiration and additive manufacturing provide an opportunity to design and fabricate advanced iso‐grids structures.

On Design of Through-Hole Structure Inspired by Vascular Bundle of Bamboo for Multiple Compression Load Cases

In this paper, the multiangle’s crashworthiness of the bionic tubes inspired by the cylindrical fibers of bamboo vascular bundles as well as the through-hole structure are studied. A finite element model validated by the theoretical analysis and drop hammer impact experiments is used to assess the optimal core distribution ratio of the bionic tube at 0°, 10°, 20°, and 30° impacts. Finally the effects of the number of circular core and wall thickness on crashworthiness are investigated. The results show that the bionic tube has better crashworthiness at small angle impacts compared to the square tubes, and l14r6 is obtained as the optimum bionic tube: the SEA at small angles improves by 12.72% (0°), 14.91% (10°), and 18.12% (20°), respectively; however, the SEA at 30° impact decreases by 2.53%. As the number of circular core increases, the crashworthiness becomes more significant, but the deformation mode becomes worse. The SEA of the tube with 32 cores increases by an average of 1.85 times (0°), 1.89 times (10°), 1.34 times (20°), and 1.41 times (30°) for each impact condition, respectively, compared to the tube with single core.

Crashworthiness design and optimization of bamboo-inspired tube with gradient multi-cells

This study seeks to understand how bamboo maintains its stability while being lightweight and flexible in strong winds, with the aim of applying the findings to develop an engineering tube that mimics bamboo’s unique structural properties. Initially, image processing revealed convex distribution along the radial direction of the fiber sheath area between bamboo nodes, which was further analyzed to examine its impact on the bending properties of bamboo. Subsequently, a new bionic tube with gradient multi-cells (BTGCs) was introduced, and its crashworthiness was investigated using the Simplified Super Folding Element (SSFE) theory to establish a theoretical model. Additionally, the influence of the structural parameters of BTGCs on its crashworthiness under different loading angles was investigated in silico. The optimal basic design parameters were selected by using the complex proportional evaluation (COPRAS) method, and a Pareto front set of bionic design parameters and impact angles was obtained using artificial neural network (ANN) and non-dominated sorting genetic algorithm (NSGA-II). The results indicated that the optimized BTGCs demonstrated superior crashworthiness compared to conventional circular and bi-layer tubes with an equal mass. This study can serve as a reference for designing highly-efficient bionic tubes.

Bionic design of thin-walled tubes inspired by the vascular structure of bamboo

In order to improve the crashworthiness and energy absorption of thin-walled tubes, this work proposes a novel design inspired by the vascular fiber sheath flap (VF) and central through-hole characteristics of bamboo vascular bundles. The energy absorption of the bionic structure is verified by experiments and theoretical analysis. Numerical simulations are used to analyze the effect of bionic unit structure and connection settings on various crashworthiness indexes. The results show that the bionic tube achieves the optimal energy-absorbing structure when the VF unit is a semicircle and the ratio of the circle core’s radius to the straight panel’s length is 3:7. Further, the effect of connection between the bionic unit and the outer tube on crashworthiness is also explored, and the optimal αβ-connection is obtained. Finally, both parallel fractal(PF) and rotational fractal(RF) approaches are introduced to improve the crashworthiness of thin-walled tubes based on the optimal structures obtained. And the crashworthiness of PF tube is better than that of the RF tube under the same level.

Design of Euplectella aspergillum based bionic thin tubes for impact absorbing application under different loading conditions

In this study, Euplectella aspergillum based thin tubes is modeled to increase the energy absorption performance. Two bio-inspired lattice structures are incorporated into the circular cross-section thin tubes. The study aims to obtain shorter wave folding and reduce the difference between peak crushing force (PCF) and mean crushing force (MCF). The modeled tubes have multi-cellular thin walls and lattice sandwich thin walls. All the tubes are tested under high-impact axial and varying oblique loading cases using finite element modeling (FEM). The study shows mainly local buckling behavior with the number of folding, fluctuation in energy absorption, and axisymmetric deformation dependent on the length, height of the unit cells, and type of loading. A parametric study shows the possibility of engineering the crashworthiness based on the unit cell design parameters. Furthermore, the experimental validation of the FEM results is carried out with the selective laser melting (SLM) process fabricated bionic tubes of Al–Si10–Mg alloy. The FEM and experimental results showed good agreement. Bionic tubes offer potential applications in advanced automobile crash boxes and lightweight structure designs.

Development of a Bionic Tube with High Bending-Stiffness Properties Based on Human Tibiofibular Shapes.

The human tibiofibular complex has undergone a long evolutionary process, giving its structure a high bearing-capacity. The distinct tibiofibular shape can be used in engineering to acquire excellent mechanical properties. In this paper, four types of bionic tubes were designed by extracting the dimensions of different cross-sections of human tibia-fibula. They had the same outer profiles, but different inner shapes. The concept of specific stiffness was introduced to evaluate the mechanical properties of the four tubes. Finite-element simulations and physical bending-tests using a universal testing machine were conducted, to compare their mechanical properties. The simulations showed that the type 2 bionic tube, i.e., the one closest to the human counterpart, obtained the largest specific-stiffness (ε = 6.46 × 104), followed by the type 4 (ε = 6.40 × 104) and the type 1 (ε = 6.39 × 104). The type 3 had the largest mass but the least stiffness (ε = 6.07 × 104). The specific stiffness of the type 2 bionic tube increased by approximately 25.8%, compared with that of the type 3. The physical tests depicted similar findings. This demonstrates that the bionic tube inspired by the human tibiofibular shape has excellent effectiveness and bending properties, and could be used in the fields of healthcare engineering, such as robotics and prosthetics.

Compressive fatigue response of Al-Si10-Mg bionic thin tubes under constant and variable amplitude loading

In this study, two different lattice structures are mimicked from the Euplectella aspergillum. These lattice structures are used to design novel bionic tubes. Bionic tubes are fabricated with Al-Si10-Mg material using selective laser melting (SLM) process. The work investigates the thin tubes' dynamic response under cyclic fatigue loading; with constant and variable amplitude. Fatigue stiffness, fatigue life, and fracture mechanism of the bionic thin tubes are compared with honeycomb based thin tubes. The deformation and fracture behavior of the thin tubes under constant and variable amplitude is compared. Results showed that the portion of fatigue life spent in damage initiation and propagation depends on the stress amplitude and design. Also, the fracture mechanism is independent of stress amplitude and depends on fatigue loading and design type. Finite element modelling (FEM) is used to compare the stress distribution in different lattices. Numerical results showed the dependence of stress distribution on the loading and tube type. Overall, when novel bionic tubes are compared with honeycomb based thin tubes, the bionic tubes showed better fatigue performance. The newly designed bionic tubes can be used as grid-stiffened structures and structural applications.

Study on energy absorption behavior of bionic tube inspired by feather shaft of bean goose

To improve the crashworthiness and energy absorption of the thin-walled tube, micro-CT is used to observe the section of the feather shaft, we extract the “sawtooth” and “semicircle” structure to design five kinds of bionic thin-walled tubes. The simulation results of axial compression and three-point bending show that the bionic tubes have higher energy absorption efficiency than the traditional square tube. At the same time, quasi-static compression experiment is carried out on BFTZ4 bionic tube (the inner sides are “sawtooth”) with the best energy absorption in numerical simulation. The energy absorption of bionic tube is compared with that of traditional square tube, and its crushing behaviors is studied. It is found that the mean load and specific energy absorption of the bionic empty tube are 1.65 times and 1.35 times that of the square empty tube, respectively. The mean load and specific energy absorption of the bionic filled tube are 1.27 times and 1.24 times that of the square filled tube, respectively. This study provides theoretical and experimental basis for the bionic design of crashworthiness.

Study on the energy absorption performance of bionic tube inspired by yak horn

To improve the energy absorption of the traditional tube, a bionic tube was proposed based on the structure and mechanical properties of yak horn. The specific energy absorption of bionic tube is 1.25, 0.89 and 1.02 times higher than that of circular tube, square tube, tapered tube. The taper(β)and the ratio of wall thickness(α) have an effect on the energy absorption. 11 kinds of bionic tubes were evaluated with the Complex Proportional Assessment (COPRAS). The energy absorption characteristics of BT-7 are better than those of other tubes. Finally, the Design-expert software was used to analyze the test results, and the optimal combination was obtained when α = 2 and β = 82°.

Experiment and numerical simulation study on the bionic tubes with gradient thickness under oblique loading

A class of bionic gradient thickness (BGT) tubes with 2 cross-sectional shapes (circle and rectangle) are proposed. The energy absorption and deformation modes of four thin-walled tubes, including a bionic circular tube (BCT), and a bionic rectangle tube (BRT) with gradient thickness, and the counterpart uniform-thickness (UT) tubes, namely circular tube (CT) and rectangle tube (RT), are analyzed by Ls-Dyna. Before detailed analysis, the simulation and bionic design are verified by quasi-static experiments, which show that the BCT has better deformation than the CT, and the experimental curves also are well consistent with the simulation. The BCT has a better energy absorption capacity when subjected to different oblique loading angles. The selection and parameterization of sample points are studied based on full-factor tests. The design factors significantly affect the specific energy absorption (SEA) and peak force (PF) of the BCT under multi-angle oblique loading. Finally, the multi-objective optimization design considering the load angle is conducted to obtain the optimal design of the BCT. The optimum BCT has a 9.3% higher SEA compared with CT. Moreover, there is a mass reduction of 4% than the CT.

Crashworthiness analysis of bionic thin-walled tubes inspired by the evolution laws of plant stems

Recently, bionic thin-walled structures have attracted widespread attention in automotive safety design because of their excellent crashworthiness behavior and weight efficiency. In this paper, inspired by the evolution laws and microstructure of plant stems, a group of bionic tubes with m parts and n layers (PmLnBTs) are proposed and investigated by theoretical prediction and numerical analysis. Theoretical models of PmLnBTs are developed to predict the specific energy absorption. Finite element model is conducted with LS-DYNA and validated by a quasi-static axial crushing experiment. The accuracy of the theoretical model is verified by numerical analysis, and the maximum relative error is less than 7%. Furthermore, parametric studies are conducted to investigate the effects of geometric parameters on the energy absorption capability of PmLnBTs. The results indicate that the PmLnBTs exhibit superior crashworthiness performance compared to traditional bi-tubular circle tubes. Moreover, when designing such a bionic energy absorber, it can effectively improve the crashworthiness performance by appropriately increasing the number of layers, reducing the outermost circle diameter or avoiding innermost circle diameter value too large or too small. The findings of this paper provide a guidance for the design of energy absorber with excellent energy absorption performance.

Study on the crashworthiness of bio-inspired multi-cell tube under axial impact

In recent years, thin-walled energy-absorbing structures have attracted more and more attention due to their excellent structural mechanical properties. In this article, one new kind of multi-cell bionic intersecting thin-walled tube inspired by the structure of the pine cone was designed. In order to fully study the crashworthiness of this new multi-cell tube under axial impact, the effectiveness of the simulation analysis is verified by the verification test of the circular thin-walled tube. Then, the crashworthiness of the circular tube and a series of multi-cell tubes were compared by means of simulation analysis. The simulation results show that the new multi-cell tube can effectively improve the efficiency of energy absorption, specific energy absorption, and crushing force efficiency under the premise of sacrificing part of the peak load. Finally, the response surface method was used to find the optimal design parameters. Response surface model (RSM) was used to represent specific energy absorption (SEA), peak force (PF), crushing force efficiency (CFE), and mass (M). Optimisation results show that the overall impact performance of the three-cell bionic tube under the axial impact load is better than that of the ordinary circular tube and several other multi-cell tubes. Therefore, the three-cell bionic tube can be used as an excellent absorption structure of collision energy under axial impact.

Bionic design in anti-bending and lightweight tube based on the tarsometatarsus of ostrich

When ostrich (Struthio camelus) runs, its tarsometatarsus swings at a high frequency and has a small mass but can carry the weight of the whole body, which is enough to indicate that tarsometatarsus has the lightweight and anti-bending properties. The results of scanning electron microscope (SEM) showed that there were no significant differences in the microstructure of different locations of tarsometatarsus. The compression test was performed, and the average compressive strength of the specimens at each sampling location was obtained. The results showed that the compressive strength of the tarsometatarsus in inside and outside orientations is smaller than that in front and back orientations. Therefore, the superior load-carrying capacity of tarsometatarsus is related to its morphological structure. Based on the morphological and structural characteristics of ostrich tarsometatarsus, the bionic tube was designed, and three kinds of tubes were designed as the control. Further, the finite element analysis of the anti-bending property of the four tubes was performed under static load. The result indicated that the bionic tube had lower mass and higher specific stiffness structural efficiency, and the result of the simulation was verified by the cantilever compression test.

Experimental study on energy absorption of bionic tubes inspired by bamboo structures under axial crushing

We report an experimental study on three new types of tubes inspired by the cross-section and nodes of bamboo with the aim of improving the crashworthiness of three types of cylindrical metal tubes: Bionic Tubes of Variable Thickness (BTVTs), Bionic Tubes with Rib (BTRs), and Bionic Tubes with Bamboo Cross-section (BTBCs), respectively. The EA capacity and deformation modes of the bionic tubes and a cylindrical tube were experimentally investigated in this study by drop-weight test. The drop test results revealed that 8 of the 14 bionic specimens exhibited greater SEA than the CT. And these results indicate that the bionic method can improve crashworthiness and affect the deformation mode under certain conditions. Different bionic feature have different effects on the deformation of thin-walled tube. Further research is required to optimize the bionic cross-section, rib, and thickness for the new types of tubes.