Energy Absorption Of Tubes Research Articles

Energy absorption in expanding metallic wire mesh tubes

The deformation process and energy absorption of metal wire mesh tubes under quasi-static expanding by a hemispherical-cylindrical indenter were investigated by experimental tests, finite element (FE) simulations and analytical modelling. Stainless steel and aluminum alloy tubes were tested on an MTS universal testing machine at a speed of 10 mm/min. The effects of mesh cell size and friction coefficient on the quasi-static force and specific energy absorption (SEA) were examined by FE analysis and analytical modelling. The analysis reveals that a combination of the mesh cell size and cross section dimension of the wire governs the energy absorption of tubes of equal overall dimension (diameter and length) and masses. In general, a decrease of the size of cells with constant height-to-width ratios leads to an increase of the specific energy absorption mainly due to the increased number of cells within the deformed region. An increase of the specific energy absorption is also achieved when the cell size is reduced by only decreasing the cell height. The maximum indenter force predicted by the proposed analytical model of the expanded tube deformation agrees well with the experimental results and FE simulations.

Oblique compression of square tubes with walls of different thicknesses

In this paper, thin-walled aluminum square tubes with three different types of wall thickness configurations were experimentally compressed at loading angles of 0°, 10° and 15°, i.e., four walls with uniform thickness (St1t1), opposite walls with the same thickness (St1t2O and St2t1O), and opposite walls with different thicknesses (St1t2A and St2t1A). Numerical analysis was further conducted to explore the effects of wall thickness, thickness configuration and loading angle on the deformation mode and energy absorption of tubes. The results show that tubes with opposite walls of different thicknesses (St2t1A) present better energy absorption performance than tubes with uniform thickness under oblique loading. In addition, tubes with opposite walls of the same thickness (St1t2O) absorb the most amount of energy under oblique compression at larger angles (20° and 30°).

Analysis of mechanical response of triple continuous nested tube energy absorber under low-speed compression of rigid plate

The nested tube system is a cost-efficient energy absorbing device that is particularly crucial for applications with constrained squeeze zones and space. Using the triple continuous nested tube (TCNT) method for nesting is quite useful. The single-stage mode and two-stage mode are its two distinctive force–displacement curve forms. In this study, finite element models suitable for TCNT structures were developed using Abaqus software, and several control groups were constructed according to different initial collapse loads. Through an in-depth analysis of each component of the TCNT, it is discovered that the stiffness competition between the two inner rings is the primary factor contributing to the step-like mechanical response. The TCNT system comprehensively outperforms the conventional single ring design for specific energy absorption (SEA). The prediction equation regarding the initial collapse load of this system is also discussed in this paper. Since the relative errors of the theoretical and numerical solutions are more concentrated, the accuracy can be increased by the amplification factor. The final polynomial fit equation obtained gives a glimpse of the full force–displacement curve.

Improving the crashworthiness of circular tube energy absorber by introducing different Gaussian curvatures on surface

Thin-walled tubes are widely used as energy absorbers in automobile vehicles to protect the occupants during a collision. Unfortunately, too high detrimental initial peak force (IPF) generated while tube crushing causes high risk and damage to the vehicle occupants. Hence, the design of such a device is vital for achieving high energy absorption (EA) with reduced peak force. Introducing a Gaussian curvature on the tube’s wall is an efficient technique to minimize the initial peak crush force. In this connection, a new structural design solution for cylindrical tubes with different Gaussian profiles (Zero, Positive, and Negative) has been proposed to improve energy absorption characteristics with reduced peak crush force. Initially, zero Gaussian curvature tubes (simple cylindrical tubes) are numerically analyzed and validated through experimental findings to prove the efficiency of the proposed numerical model. Subsequently, positive and negative Gaussian curved tubes were analyzed numerically. Their IPCF and EA were evaluated and compared. IPCF of positive and negative curvature tubes was reduced by 20–50% and 5–10%, respectively compared to zero curvature tubes. Since the proposed tube structures are of considerable potential, they can be employed as protective systems in place of conventional tubes in vehicles.

Crashworthiness analysis of shrink circular tube energy absorbers with anti-climbers under multiple loading cases

Energy-absorbing structures with anti-climbers for railway vehicles rarely experience pure axial loading in real crash events, but rather a combination of axial and off-axial loads. In this perspective, it is critical to understand the non-centric collision process of energy absorbers. To address this issue, this paper aims to investigate the crashworthiness of shrink circular tube energy absorbers with anti-climbers under vertical, horizontal eccentric and oblique loads comprehensively. Finite element (FE) models of the shrink circular tube energy absorber with anti-climbers are then developed and validated by a physical impact experiment. The numerical results show that the different eccentric distances and oblique angles affect the crashworthiness of the proposed energy absorber significantly. The energy-absorbing structure exhibits a stable and controlled deformation pattern as well as a very high energy absorption efficiency in offset collisions at different vertical heights. However, when the horizontal offset distance exceeds half of the anti-climber width, the energy-absorbing circular tube suffers an overall destabilizing deformation, failing in the energy-absorbing capacity. Additionally, the proposed energy absorber is suitable for oblique load collision scenarios that the oblique angle is no more than 10°. Finally, the response surface modeling technique and non-dominated sorting genetic algorithm are employed to optimize the key structural parameters of shrink circular tube energy absorbers under multiple loading cases. The results exhibit that an optimized shrink circular tube energy absorber is more competent in crashworthiness for multiple load cases.

Energy absorption of fully clamped multi-cell square tubes under transverse loading

This paper investigates energy absorption performance of multi-cell tubes considering the influence of axial constrain in bending process Firstly, three-point-bending tests and fully clamped bending tests were conducted. Experimental results showed that the energy absorption of tubes increased to 2.5–3 times if the end of the tube is constrained. Based on the FE model verified by experiments, the effect of rib direction and rib number is investigated under fully clamped condition. Results show that the multi-cell tubes with rib parallel to the load direction (MT-Y0Zn) have better energy absorption performance than that with rib perpendicular to the load direction (MT-YnZ0), especially in the frontal part of bending process. Meanwhile, following with the increase of rib number, specific energy absorption (SEA) of MT-Y0Zn increases gradually, while SEA of MT-YnZ0 remains almost unchanged. Considering the fact that MT-Y0Zn shows better energy absorption performance, theoretical model of MT-Y0Zn is established and highly consistent with FE model. Finally, the influence of thickness and cross-section size is discussed. SEA increases with increase of cross-section and remains unchanged with increase of thickness as predicted by theory. However, when cross-section exceeds 80 mm or thickness is smaller than 1 mm, local denting caused by shear force decreased SEA significantly.

Crashworthiness performance and multiobjective optimization of a combined splitting circular tube energy absorber under eccentric impact for subway vehicles

This paper proposes a new type of combined splitting circular tube energy absorber for subway vehicles. An impact experiment is conducted to investigate the dynamic crushing performance of this combined splitting circular tube energy absorber. The results show that the combined tubes experience steady dynamic splitting deformation. The crush force efficiency (CFE) and effective stroke ratio (ESR) of the combined splitting circular tube energy absorber are 85.7% and 85.9%, respectively. A theoretical solution for the dynamic splitting crushing load is derived. Finite element (FE) models of the energy absorber are then established, and the dynamic crushing forces agree well with those of the impact experiment. The cumulative error and validation metrics of the crushing force obtained from the numerical simulation and impact experiment are 0.0938 and 0.9122, respectively. The effect of the strain rate of AISI 1020 steel on dynamic steady-state forces is analytically studied, and the results are compared with those of FE simulations and impact experiments. The numerical results show that the dynamic steady-state force of the combined splitting circular tubes under dynamic loading increases by 31.69% compared to that of the tubes under quasistatic loading. The effects of various structural parameters are discussed using the validated FE models. The results show that the combined splitting tube energy absorber has excellent crashworthiness under eccentric loading. The eccentric impact of the two absorbers has a significant influence on the crashworthiness performance of the structure. The specific energy absorption (SEA) increases by 15.2% as the eccentric distance increases from 20 to 80 mm. Compared with the influence of the wall thickness t of the combined splitting circular tubes, the tube radius and die angle have a more significant influence on the SEA. To improve the crashworthiness of combined splitting circular tubes under eccentric loading, a Pareto front of the SEA and average axial crushing force (AACF) under an eccentric distance of H = 40 mm was obtained after optimization by multiobjective particle swarm optimization (MOPSO). The results show that the SEA and AACF are positively correlated and that a balance between the SEA and AACF was obtained at optimal point B (SEA = 14.6 kJ/kg and AACF = 938 kN).

Energy-absorption assessments of perforated CFRP tube induced by inward-splaying trigger with different trigger radius

For different purposes of engineering design, CFRP structure inevitably be processed with open holes, resulting in the discontinuity of fiber or matrix and reducing structural performance. To improve crashworthiness, the crushing behaviors of perforated CFRP tube with different trigger radius based Inward-Splaying Triggers (IST) are studied. The finite element method with the non-linearly progressive damage model is adopted for verifications and numerical investigations. The improve effect and trigger mechanisms of IST on the perforated tube is revealed by comparing with original tube. To extensively reveal the energy-absorption (EA) behaviors, the analyses of parameters including trigger radius, radius and position of open-hole are investigated. It is found that increasing open-hole radius can aggravate hole circumferential fracture and position of open-hole has significant effect on EA of tube with IST. By comparisons, any perforated tube with IST has higher total EA than intact tube. It is indicated that much improvements of EA are attributed to the fact that a transition from hole circumferential fracture to progressive crushing can be achieved by IST, leading to more adequate energy dissipation of materials. Several crucial conclusions from the parameter analyses are drawn for guiding the perforated structural design and improving crashworthiness.

Energy absorption behaviour of an aluminium foam-filled circular-triangular nested tube energy absorber under impact loading

A novel aluminium foam-filled circular-triangular nested tube (AFCTNT) energy absorber was developed in this study, and its energy absorption behaviour under impact loading was experimentally and numerically studied. Drop-weight impact tests on the AFCTNT energy absorbers with different volumes of aluminium foam filler were first conducted to obtain their energy absorption parameters, force–displacement responses, and deformation modes. In addition, numerical studies on AFCTNT energy absorbers were also carried out, and the specific energy absorption of nested tubes and aluminium foam were obtained to further reveal their energy absorption performances. Experimental results indicated that the deformation modes of AFCTNT energy absorbers were evidently affected by the volume of aluminium foam filler. Moreover, the energy absorption performances of AFCTNT energy absorbers were found to be significantly improved by filling aluminium foam in terms of higher energy absorption, specific energy absorption, mean crushing force, and crushing force efficiency. Both experimental and numerical results demonstrated that the AFCTNT energy absorber with fully-filled aluminium foam outperformed the other AFCTNT energy absorbers owing to more significant interaction effect between the nested tubes and aluminium foam.

Axial Crush Response of Aluminium Square Tube with Origami Patterns

Thin-walled square tubes are widely used as impact energy absorber in automotive structures due to their ease of fabrication and installation, high energy absorption capacity in terms of progressive plastic deformation and long stroke. However, the main drawback of square tube is its high initial peak force during the initial stage of crushing. An origami pattern on the faces of the tube is proposed to reduce the high initial peak force and increase the energy absorption of the tube. Static and dynamic axial crushing were performed using finite element analysis to determine the initial peak force (IPF), crush force efficiency (CFE) and plastic specific energy absorption (SEA) of tubes with origami pattern. The results of simulations were validated by experimental data. Then, various combinations of origami patterns were studied using finite element simulation only. It was found that the origami pattern significantly enhanced the tubes crush performance. Comparison between plain square tube and tubes with various origami patterns was carried out and it was found that the origami patterns reduced the initial peak force and increased the crush force efficiency for both static and dynamic loading conditions.

Crashworthiness Analysis of Octagonal-Inner Double Tube with different thickness under Off-Axis Oblique Load

The crash tube is one of the important parts to reduce the effects of accidents. The design of crash tube only watches the frontal crash, but oblique crash might affect the passengers. Besides, Lack of oblique-loading researches in crashworthiness becomes causes to analyze crash tubes more. This paper aims to study crashworthiness performance of octagonal-inner double tubes under off-axis oblique impact load (0°, 10°, 20°, and 30°). The tubes have been connected with two walls, top wall as moving wall and a bottom wall as rigid wall underl different load angles. The tubes were made from Aluminum Alloy and consisted of a circular-outer tube and an octagonal-inner tube. The crashworthiness parameters of absorption of specific energy (SEA), maximum collapse force (Fmax) and efficiency of crush force (CFE) were obtained for all the structures. In order to get the value of parameters, the method of finite element analysis was used. The effects of different thickness of 1 mm, 2 mm, 3 mm and 4 mm and various oblique were studied. Based on numerical results, structures of 4 mm thickness were the greatest SEA of 26.39 kJ/kg among other thickness of structures. In addition, the value of energy absorption for tubes obliquely loaded decreased for all the size of thickness structures. Finally, this structure can be considered as crash box of vehicle in future

Experimental research of absorption properties of rigid foam filled circular seamless tube energy absorber under quasi-static axial load

The aim of this research work is investigations of absorption characteristics of a circular seamless tube collision absorber filled by rigid polyurethane (PU) foam under axial load. Shrinking of circular tube passing through cone bushing starts after absorber is activated at the moment of collision. The energy absorption realises in three ways: elastic-plastic deformation of the tube wall, friction between absorption elements and compression the rigid PU foam inside the tube. Using rigid PU foam, as the seamless tube filler, in the process of collision energy absorption increases absorption power in comparing to with only empty tube, as well as gives gradual increases of deformation resistance during deformation process. Experimental research was prepared and realized in the laboratory using the scaled samples. The effect of rigid PU foam, configuration of absorber filled by PU foam on the absorption power and manufacturing technology of the samples, are considered and discussed in this paper. The results indicate that the shrinking foam filled tube absorber has for about 18% bigger absorption power than the empty one. Formation of numerical model and numerical analyses of shrinking foam filled tube absorber were realized using ANSYS software package. Force vs. stroke (F(s)) diagrams obtained by tests and numerical analyses are in a good correlation which confirms formed numerical model as a suitable for further quasi-static analyses and for dimensioning the similar types of absorber.

Crashworthiness analysis and multi-objective optimization of expanding circular tube energy absorbers with cylindrical anti-clamber under eccentric loading for subway vehicles

This paper presents an investigation of the crashworthiness of expanding circular tube energy absorbers with a cylindrical anti-clamber under eccentric loading for subway vehicles. A finite-element model of energy absorbers is created and validated by two quasi-static experiments, and the strain rate sensitivity is evaluated using standard coefficients of the Cowper-Symonds constitutive model. A parametric study is performed using the validated finite-element models. It is found that the eccentric collision of two energy absorbers has a significant effect on their crashworthiness and leads to a decrease in the specific energy absorption (SEA) and an increase in the peak crushing force (PCF). The structural parameters of the energy absorber, including the wall thickness t, conical angle α, and punch radius rp, have a significant effect on its crashworthiness under different eccentric distances. Sobol sensitivity analysis is employed to analyze the effects of the design parameters (t, α, and rp) on the objective responses (EA and PCF). The results show that the design variables t and α have a greater effect on the sensitivity of the EA and PCF functions for the eccentric distance of h = 0 and 40 mm. The interaction between punch angle α and punch radius rp has significant effect on EA. To improve the crashworthiness of the expanding circular tubes, a multi-objective optimization is applied to achieve the maximum EA and minimum PCF values, and weight factors are introduced to investigate the crashworthiness optimization under single-eccentric loading and multiple-eccentric loading. The optimization solutions of the expanding circular tubes under different single-eccentric loadings have considerable implications. For multiple-eccentric loading, the results show that the crashworthiness of the expanding circular tube energy absorber can be better balanced.

Energy absorption properties of thin-walled square tube with lateral piecewise variable thickness under axial crashing

Purpose This paper aims to study the energy absorption properties of the thin-walled square tube with lateral piecewise variable thickness under axial crashing and the influence of the tube parameters on energy absorption. Design/methodology/approach In this work, the energy absorption properties of the thin-walled square tube were analyzed by theoretical, numerical and experimental approach. The numerical results are obtained based on the finite element method. The explicit formulation for predicting the mean crushing force of the tube with lateral piecewise variable thickness was derived based on Super Folding Element method. The limitation of the prediction formulation was analyzed by numerical calculation. The numerical calculation was also used to compare the energy absorption between the tube with lateral piecewise variable thickness and other tubes, and to carry out the parametric analysis. Findings Results indicate that the thin-walled tube with lateral piecewise variable thickness has higher energy absorption properties than the uniform thickness tubes and the tubes with lateral linear variable thickness. The thickness of the corner is the key factor for the energy absorption of the tubes. The thickness of the non-corner region is the secondary factor. Increasing the corner thickness and decreasing the non-corner thickness can make the energy absorption improved. It is also found that the prediction formulation of the mean crushing force given in this paper can quickly and accurately predict the energy absorption of the square tube. Originality/value The outcome of the present research provides a design idea to improve the energy absorption of thin-walled tube by designing cross-section thickness and gives an explicit formulation for predicting the mean crushing force quickly and accurately.

Impact Loads on the Occupant under the Protection of an Inversion Tube Energy Absorber during a Helicopter Crash

The objective of this paper is to investigate the impact loads on the occupants’ head, neck, and spine under the protection of an inversion tube energy absorber during a helicopter crash landing. Due to the high vertical acceleration, the head, neck and spine are the most vulnerable parts of a body, so that an energy absorber is needed to dissipate the kinetic energy of the occupant and the seat to minimize the impact loads. In this paper, an inversion tube was adopted as an energy-absorbing device. The occupant injury conditions were evaluated by a numerical simulation. The result indicates that the impact loads on occupant’s head, neck and spine are below the regulated thresholds under the protection of the energy absorber when the helicopter crash at a speed of 12.81m/s in vertical direction. As a consequence, the design of the occupant protection system has been proven reliable.

Analysis and application of energy absorption characteristics of expansion tube type absorber

Passive safety protection technology is to reduce the damage caused by collision by improving the anti-impact performance of the system itself. It has important engineering practical value. Many scholars have carried out the research on the collision design of the train in the structure design of the track vehicle. The core is to absorb the kinetic energy of the collision by absorbing energy structure to reduce the force generated during the collision and minimize casualties. The expansion tube type absorber is usually used as a collision safety protection device in the track vehicle. The quasi-static compression test is carried out for the expansion tube type absorber. The energy absorption characteristics and compression characteristics of the expansion tube energy absorber in quasi-static compression test are studied experimentally. The design and research of the energy absorber for rail vehicles are of guiding significance and practical value.

Cutting Deformation Mechanisms of Square Aluminium/CFRP Tubes

The aim of this study is to find the best platen with blades as a new energy dissipating mechanism that causes considerably damage to CFRP/aluminium tubes. Specially designed and manufactured platens with five different cutting blade profiles were used to simultaneously cut and crush square CFRP tubes and aluminium sheet-wrapped CFRP tubes. The platens with blades were evaluated in terms of the deformation mode, mean crushing force, energy absorption and specific energy absorption of tubes. Experimental results showed that tubes cut and crushed by the platen with 45o inclined blades had the best crushing performance and exhibited a more stable deformation mode compared with those for tubes cut and crushed by other platens with different blade profiles. The platens with blades acted as trigger mechanisms that minimise the initial peak crushing force and maximise the energy absorption of tubes compared with tubes crushed by flat loading platens.

On the energy absorption of tube reinforced foam materials under quasi-static and dynamic compression

Theoretical and numerical analyses are carried out to reveal the role of metal tube reinforcement in the enhancement of the energy absorption capacity of foam materials with different densities and strength. A theoretical model is proposed to estimate the strength increase of the reinforcement due to the confined tube, which buckles. Using this model, the contribution of the reinforcement is obtained to the mean quasi-static tube force and also to the total quasi-static average force of reinforced materials comprising different foam and reinforcing components. The proposed model is also used to estimate the efficiency of the reinforced foam materials in the quasi-static loading regime.FE simulations are carried out to verify the theoretical quasi-static model and to examine some essential dynamic effects due to the inertia of the foam and reinforcing tubes on the energy absorption of the material when subjected to impact loading. Attention is paid to the force enhancement at the impacted end and to the dynamic load transfer to the distal end of blocks of reinforced materials.

Experimental and numerical study of circular, stainless thin tube energy absorber under axial impact by a control rod

In this study, several crashworthiness parameters of a circular, thin tube energy-absorbing structure, which is used in a high-temperature, gas-cooled reactor (HTR), are studied experimentally and numerically at various tube thicknesses, temperatures and impact velocities. The average crushing force is fundamentally dependent on strain hardening, strain rate hardening, and, particularly, temperature softening of the material. The peak forces during buckling are significantly affected by the local strain rate in the material and exhibit a decreasing trend in sequentially formed folds. Reducing the tube thickness is an effective method to weaken the average crushing force, but it does not weaken the maximum crushing force. Additionally, the stress concentration at the edge of the backplate–graphite contact surface is evaluated in detail to ensure the structural security of the energy absorber.

Crush Force Efficiency of Composite Square Profile under Off-Axis Loading

The present paper determines the effect of crush force efficiency on laminate glass wrapped on aluminum cross-section square tubes under quasi-static loading. The analysis was examined via experimentally. The wall-thicknesses aluminum square of 1.6 mm was investigated on wrapped woven composite type of E-glass fiber reinforced polyester resin. Two different numbers of layers woven E-glass were investigated and examined. Result obtained from experimental analysis such that initial peak load, mean load, versus displacement curves were compared for each specimen. Results showed that the tubes energy absorption was affected significantly by different number of layers wrapped on wall aluminum square profile and also that the effect of crushing behaviors and failure modes was discussed.