Energy Absorption Devices Research Articles

Investigation of Metal Composite Briquette Operation in Absorption Equipment Friction Units

Reasons are considered for unsatisfactory operation of the energy-absorbing device of railway wagon drawbar, whose main element is a friction plate with special energy-absorbing cermet coating. The main specifications for the friction plate are resistance to shock loads, resistance to thermal cycles in the temperature range from ambient temperature to 850–870°C, good resistance to shear stresses, friction coefficient stability in this temperature range, lack of seizure to friction wedge material made of steel, and long operating life up to 10,000 loading cycles. According to results of metallographic studies using optical and scanning electron microscopy with energy dispersion microanalysis it is established that the poor quality of the friction plate metal composite coating is caused by the following factors: localization of eutectic containing sulfur, iron, and manganese along the “ceramic-substrate” boundary, and presence of oxide films on the surface of precursor powder particles. As a result of this excess interfaces arise in cermet material that are areas of microcrack formation during cermet operation. Thermal stresses arising during metal composite briquette manufacture lead to crack development at the interface of metal composite and a steel base. Application of unevenness to the steel base of metal composite material in a hydrogen or endogas atmosphere makes it possible to avoid both thermal cracks and subsequent metal composite separation during operation. An improvement in operating characteristics is confirmed during laboratory tests under conditions approximating operational.

Numerical Evaluation of the Steel Plate Energy Absorption Device (SPEAD) for Seismic Strengthening of RC Frame Structures

In this paper, a new strengthening technique is proposed: the Steel Plate Energy Absorption Device (SPEAD) system, which is intended to increase the flexural strength of beam and column members in RC frame structures. In this way, while permitting calibration of the strength increase in the beam to comply with the strength hierarchy criteria needed for a proper seismic behaviour it can provide additional energy absorption. A numerical evaluation of the SPEAD system is carried out by means of a refined 3D model built with an advanced nonlinear finite element program. The SPEAD system has been virtually applied (through finite element analyses) to an RC external beam–column joint, representative of typical existing RC buildings, and the numerical results are compared to those of a specimen that was not upgraded and subjected to the same experimental tests. The SPEAD upgraded model provided a strength increment of about 50% with also a strong reduction of bond-slip effects in the joint panel region. This latter, in turn, provided a beneficial increase of ductility. Based on the positive results from numerical simulations, a design method is also provided.

Crashworthiness analysis and collaborative optimization design for a novel crash-box with re-entrant auxetic core

Crash-box is a significant part of automotive passive safety system and serves as a main energy absorption device in frontal impact scenario. In this paper, a novel crash-box integrating an outer thin-walled tube and an inner auxetic cellular core has been designed and comprehensively investigated under axial load. The impact simulation of the auxetic crash-box has been carried out, and the results show that introduction of the auxetic core can improve its energy absorption capacity without increasing too much peak impact force. Based on the sensitivity analysis, the effects of its geometric parameters on the crashworthiness performance have been studied. Finally, collaborative optimization of the auxetic crash-box has been performed to simultaneously improve its crashworthiness under the low-speed (15 km/h) and high-speed (40 km/h) impact cases. In the optimization procedure, the least square support vector regression (LS-SVR) method and an improved particle swarm optimization (IPSO) algorithm with time-varying coefficients have been utilized. The results demonstrate that the optimized crash-box can comprehensively improve the energy absorption and impact force characteristics effectively. The auxetic crash-box and the collaborative optimization approach provide extensive references for the application of auxetic structure in vehicle crashworthiness design.

Crashworthiness of innovative hexagonal honeycomb-like structures subjected to out-of-plane compression

Seeking for innovative structures with higher mechanical performance is a continuous target in railway vehicle crashworthiness design. In the present study, three types of hexagonal reinforced honeycomb-like structures were developed and analyzed subjected to out-of-plane compression, namely triangular honeycomb (TH), double honeycomb (DH) and full inside honeycomb (FH). Theoretical formulas of average force and specific energy absorption (SEA) were constructed based on the energy minimization principle. To validate, corresponding numerical simulations were carried out by explicit finite element method. Good agreement has been observed between them. The results show that all these honeycomb-like structures maintain the same collapsed stages as conventional honeycomb; cell reinforcement can significantly promote the performance, both in the average force and SEA; full inside honeycomb performs better than the general, triangular and double schemes in average force; meanwhile, its SEA is close to that of double scheme; toroidal surface can dissipate higher plastic energy, so more toroidal surfaces should be considered in design of thin-walled structure. These achievements pave a way for designing high-performance cellular energy absorption devices.

Influence of the Geometric Parameters on the Densification Onset Strain of Double‐Walled Honeycomb Aluminum under Out‐of‐Plane Compression

As a material widely used in various lightweight structures and energy absorbing devices, honeycomb aluminum has high specific stiffness and specific strength, excellent energy absorption capacity, and vibration damping. When evaluating the energy absorption of honeycomb aluminum under out‐of‐plane compression, platform stress and onset strain of densification have become important parameters studied by many scholars. In this work, based on the theory that the energy absorption efficiency determines the densification onset strain, the influence of the geometric design parameters of honeycomb aluminum on the onset strain of out‐of‐plane quasi‐static compression densification is studied. Based on the results of the finite element analysis, the relationship between the onset strain and the geometric design parameters including cell size length and wall thickness is fitted by the least squares method. A linear relationship that the onset strain of densification will decrease with the increase of the reciprocal of cell side length and the onset strain of densification will decrease with the increase of the wall thickness is exhibited in the conclusion. This work can provide a theoretical basis for the calculation of the platform stress in the plastic deformation stage.

Numerical investigation on the effect of wall thickness on quasistatic crushing properties of nylon honeycomb structure

Honeycomb structures are extensively used energy-absorbing structures in the airplane, spacecraft and automobile body parts. The critical parameters that influence the aggregate energy absorption are cell size, wall thickness and node length. However, wall thickness is a crucial determining factor for crushing and buckling. The type of failure manifested to the crushing of the cells can be predicted with unit cell buckling. The current work investigated on quasistatic crushing properties of honeycomb structure by varying unit cell wall thickness and at constant cell size of 10 mm. The out of plane quasistatic compression test of nylon honeycomb core of various wall thicknesses i.e 1, 1.1, 1.2, 1.3, 1.4 and 1.5 mm is carried out using ANSYS 14 simulation. The results obtained from the test are in close agreement with unit cell buckling analysis for predicting the mode of failure. The ultimate compressive strength of 1.5 mm cell is observed to be 1.4 folds higher than that of 1 mm cell. The energy absorption obtained from load-displacement graph during compression test indicates the proportional relationship between wall thickness and energy absorption. High energy absorption ability for 1.5 mm wall thickness core infers superior crushing strength enables to use as energy-absorbing devices, where lightweight and strength are the prime concern.

Lean methods for energy absorption computation of thin-walled composite tubes

CFRP (Carbon fiber reinforced polymer) based composites are being widely used as materials in the transportation domain for vehicular structures as energy-absorbing devices due to their high specific energy absorption ability. The design process which is iterative for the designs with such anisotropic materials requires several material parameters for the design validation using empirical or numerical techniques. In the absence of design calculations, the design validation which needs to be done using experimental techniques which would also require very capital-intensive equipment like high-speed cameras, to assess the damage evolution behaviour. The current study surveys different damage evolution methodologies available in the literature for composites and suggests a methodology that requires lean material data. The study also highlights the methods to estimate the dynamic forces in CFRP based structures, using quasi-static study results. The proposed methods can be effectively used for evaluation and comparison of multiple intermediate designs and shortens the product development cycle. The proposed methods are applied to thin tubular composite designs subjected to impact loads, whose design intent is to absorb the energy.

Structural performance of beam system with T-stub type slit damper

In this study, the structural performance of a beam system with a beam-to-column connection-type damage-controlled system was investigated. First, a connection detail with improved geometry was proposed based on results obtained from previous studies. The proposed connection detail uses a horizontally arranged steel slit damper as an energy absorption device and consists of support elements to help the effective bending and shear behavior of the slit damper. The overall behavior characteristics are similar to the Simpson strong-tie connection; however, the energy absorption device of the proposed detail is installed only at the bottom of the beam, and the connector attached to the top of the beam functions as a rotational hinge. The strength formula of the beam system with a new connection detail was derived according to the mechanical behavior pattern. The stiffness formula of the beam system was proposed considering the geometric characteristics of the connection elements. For practical verification, a cyclic loading test was conducted on the beam-to-column connection with a T-stub type slit damper designed with appropriate strength. Nonlinear finite element analysis (FEA) was also conducted using the aspect ratio of the beam and damper strength as variables. The test and FEA results confirmed that the strength and stiffness of the beam system with the proposed connection detail exhibited responses similar to the predicted values. When the damper strength was designed to be lower than that of the beam, the deformation caused by the rotational behavior of the connection was concentrated on the damper according to the moment gradient generated in the flexural members. As the damper/beam yield strength ratio or rotation angle increased, the plasticity of the beam was found to gradually strengthen. A performance curve was derived from the relationship between the strength of the beam system and the damage to the beam according to the damper strength design conditions. It is expected that a moment-resisting frame that satisfies the requirements can be designed by applying this derived performance curve to low- and mid-rise steel buildings. Finally, the hysteretic model of the beam system with the proposed connection detail was developed through an approximation to a tri-linear model according to the design condition.

Study of kinematics of elastic-plastic deformation for hollow steel shapes used in energy absorption devices

Study of kinematics of elastic-plastic deformation for hollow steel shapes used in energy absorption devices

Numerical and experimental studies on compressive behavior of Gyroid lattice cylindrical shells

In this paper, Gyroid lattice cylindrical shell (LCS) specimens were designed by a newly proposed mapping methodology and were fabricated by selective laser melting (SLM) technology. Their energy absorption and deformation modes were investigated through quasi-static compression tests. A finite element model (FEM) was proposed, which was validated by the experimental results, for a further study on the compressive behavior of the Gyroid LCS. Based on the numerical study, it was found that Gyroid LCS showed superior energy absorption to the hexagonal LCS and triangular LCS with the same density. In addition, a parametric study indicated that main energy absorption factors, namely total energy absorption, specific energy absorption and mean crushing load, were in power function relationship with the relative density. Finally, it was found that thickness gradient and geometric gradient had significant effects on the failure modes of Gyroid LCS under compression. The research in this paper is expected to provide some guidance for the design of energy absorption devices or structures.

High-velocity perforation behaviour of sandwich panels with Al/SiCp composite foam core

Aluminium foam core sandwich panels are good energy absorbers for impact protection applications, such as light-weight structural panels, packing materials and energy absorbing devices. In this study, the high-velocity perforation response of a range of sandwich panels with Al A356/SiCp composite foam core and 1100 aluminium face-sheets has been investigated using a conventional gas gun. Impact perforation tests were carried out using a 10-mm diameter conical nosed indenter at velocities up to that required to achieve complete perforation of the target (i.e. 230 m/s). The effects of face-sheet thickness, density and thickness of aluminium composite foam core on the total, specific and extra absorbed energy and also ballistic limit of the panels during impact penetration were experimentally investigated. During test, top face-sheets globally bended and tore into several pieces and so absorbed part of impact energy. Rupture and densification are two deformation modes and energy absorption mechanisms of foam core. Localized indentation and tearing, global bending and delamination were also observed on back face-sheets. Higher foam core density and thickness and also thicker face-sheets resulted in higher absorbed energy and ballistic limit.

Experimental study of a honeycomb energy-absorbing device for high-speed trains

Aluminium honeycomb is a light weight, thin-walled material with a typical multi-cellular construction and a good strength-to-weight ratio. Therefore, aluminium honeycomb can be used as an energy-absorbing device for high-speed trains. Due to its large mass and high operating speed, a high-speed train can generate large impact energy. Thus, an energy-absorbing device with a greater energy absorption capability must be designed for high-speed trains. To reduce the aerodynamic drag, the cross-sectional area of a high-speed train is limited. Therefore, a honeycomb energy-absorbing device should be designed in such a way that it is longer than the traditional energy-absorbing devices; however, this may lead to bending, destruction and uncontrollable deformation of the honeycomb; these factors are not conducive for energy absorption. In this paper, a sleeve structure was designed for high-speed trains, and a crash experiment of the energy-absorbing structure showed that the bending and destruction of the honeycomb energy-absorbing device are effectively suppressed compared with the ordinary honeycomb energy-absorbing structure. Moreover, the fluctuation of the crash force was smaller and the crash force is more stable than the traditional thin-walled energy-absorbing structure. Therefore, the deformation instability problem of the ordinary honeycomb energy-absorbing structure and the crash force fluctuation problem of the traditional thin-walled energy-absorbing structure can be solved. Then, a crash experiment and simulation involving a high-speed train with improved honeycomb energy-absorbing device was carried out, and the results showed that the deformation of the end of the train body was stable and controllable, and the train body deceleration satisfied the collision standard EN15227.

Analysis of the crashworthiness design and collision dynamics of a subway train

In this study, the crashworthiness of a subway train was assessed by establishing a finite element model for the first three carriages of the train and the track using the Hypermesh software. By utilising the *MAT_HONEYCOMB material model, a honeycomb in an anti-climbing energy-absorbing device was simulated. Moreover, the process of a subway train – travelling at a speed of 25 km/h – colliding with another identical train in a stationary and non-braking state was simulated by employing the finite element analysis software Hypermesh and LS-DYNA. The process of simulation analysis was divided into two parts: (1) analysis of the anti-climbing energy-absorbing devices under static compression for the investigation of energy absorption and (2) collision analysis of the whole train. The contributions of the proposed energy-absorbing structure – at the end of driver’s cab, the coupler and draft gears on each section – to the overall energy absorption in a train collision were calculated. Furthermore, based on the EN15227 standard, the crashworthiness of the train with respect to the survival space for occupants, train acceleration and uplift of wheels relative to the track was evaluated. The coupler of the first carriage fails in a collision at 25 km/h, and the coupler and draft gear are the main energy-absorbing devices. *MAT_HONEYCOMB was used to define the honeycomb materials in anti-climbing energy-absorbing devices and could simulate the mechanical performance thereof. The crashworthiness of the train meets the relevant standard requirements.

Modeling and optimization of the crushing behavior and energy absorption of plain weave composite hexagonal quadruple ring systems using artificial neural network

Composite structures are being increasingly utilized in the automotive industry for their lightweight and specific energy absorption capabilities. Recently, the Composite Hexagonal Quadruple Ring System (CHQRS) has been proposed as a passive energy absorber device, due to its performance quality. Experiments show that the energy absorption capacity of this system significantly varies dependent on the interior hexagonal ring angle value. Thus, there is a need to develop an accurate model, which can be evaluated based on its performance, to then be used for predictions of its nonlinear loading capacity at various angle configurations and to optimize the interior hexagonal angle for a maximum system energy absorption capability.Within this paper, Artificial Neural Network (ANN) based models have been developed, optimized and compared using the Mean Squared Error (MSE) performance function, with the objective to precisely predict the high non-linear crushing behavior of the CHQRS at different angle configurations, as well as to optimize its internal hexagonal angle for a maximum energy absorption capability. The predicted results and the experimental results have also been compared in terms of their load carrying capacity and energy absorption capability. The developed ANN-based models accurately predict the load carrying capacity and the energy absorption capability at different angles, with an MSE of as low as 0.39 N and 1 J, respectively. The best ANN model has been identified and then utilized to optimize the internal angle of the CHQRS, in order to maximize its energy absorption capabilities; this was found to be 47°, with an energy absorption value of 69 J. For an angle of 35°, the energy absorption was 62 J.

Energy absorption of pre-folded honeycomb under in-plane dynamic loading

Abstract Honeycomb structures have been extensively employed as energy absorption devices. This paper proposes a kind of energy absorption structure known as the pre-folded honeycomb, which is made from conventional honeycomb with a pre-folded trace. The folding mode and energy absorption performance of the pre-folded structure under in-plane impact load were investigated both numerically and experimentally. Furthermore, the response surface method was chosen to find the optimal pre-folded honeycomb structure for the purpose of maximizing the specific energy absorption. The results demonstrate that the proposed method is effective in solving crashworthiness design-optimization problems. Additionally, the numerical results show that the in-plane structural strength of pre-folded honeycomb is nearly 8 times higher than that of conventional honeycomb.

Low-Velocity Impact Response of Discontinuous Kirigami Cruciform Sandwich Panel

Cruciform structures have desirable energy absorption capacity. However, the engineering application is limited by the difficulties in the manufacturing process. In this paper, a kirigami approach is introduced to simplify the manufacturing process. Based on the kirigami strategy, a structure referred to as a discontinuous kirigami cruciform sandwich panel (DKC), is investigated to validate the mechanical performance in energy absorption. Experiments and numerical simulations were carried out to investigate the impact resistance of DKC under four levels of impact energy and the energy–absorption performance is evaluated by comparing to a typical energy–absorption device, pyramidal truss sandwich panel (PT). In order to reduce the initial impact force and the displacement of the bottom surface on the protected objective, the DKC is further optimized by introducing an additional cutout at the opposite end in each component plate. With the new design, the displacement of the bottom surface on the sandwich structure is reduced by 13.9%, together with a decrease of impact peak force and an increase of energy absorption.

Theoretical analyses of mechanical performance of higher-order vertex-based hierarchical square cell structure subjected to compression

Hierarchical structure has gained great popularity in recent years, due to its significant promotion on structural strength and stiffness. In this study, the concept of high-order vertex-based hierarchy structure (VHS) was incorporated based on the new-rising multi-cell square tubes by replacing every vertex with scaled itself, layer by layer. The theoretical solution of VHS structure subjected to static compression has been conducted, based on the classical Super Folding Element. Mean crushing force ( MCF, P ) and energy absorption E have been calculated theoretically. The innovative finding lies that the relationship of the mean load between case lever i to lever i+1 has been determined. The relationship of the mean load between case lever i to lever i+1 mainly related to the cell number and length scale. All these achievements shield a light in aid to design novel thin-walled and light-weight energy absorption device.

Energy absorption behaviors of pre-folded composite tubes with the full-diamond origami patterns

Carbon fiber reinforced plastics (CFRP) has demonstrated significant promise to improve the performance-to-weight ratio in automotive and aerospace sectors. Nevertheless, traditional thin-walled CFRP tubes still have several defects such as a high initial peak force with a relatively low mean crushing force and unstable collapse mode, which significantly reduce their performance when used as energy absorption devices. In this study, the full-diamond origami pattern was introduced to thin-walled CFRP tubes. The effect of the origami patterns on the energy absorption properties and collapse modes of these tubes subjected to quasi-static axial loads was investigated both experimentally and numerically. A comprehensive parametric study on the geometrical parameters and ply stacking sequence of pre-folded CFRP tubes was conducted. Moreover, a comparison between the pre-folded CFRP tube and the metal counterpart was performed, which shows that CFRP pre-folded tube can effectively reduce the initial peak forces while increasing the overall energy absorption capacity.

Enhanced Fault Current-Limiting Circuit Design for a DC Fault in a Modular Multilevel Converter-Based High-Voltage Direct Current System

The main weakness of the half-bridge modular multilevel converter-based high-voltage direct current (MMC-HVDC) system lies in its immature solution to extremely high current under direct current (DC) line fault. The development of the direct current circuit breaker (DCCB) remains constrained in terms of interruption capacity and operation speed. Therefore, it is essential to limit fault current in the MMC-HVDC system. An enhanced fault current-limiting circuit (EFCLC) is proposed on the basis of fault current study to restrict fault current under DC pole-to-pole fault. Specifically, the EFCLC consists of fault current-limiting inductance L F C L and energy dissipation resistance R F C L in parallel with surge arrestor. L F C L reduces the fault current rising speed, together with arm inductance and smoothing reactor. However, in contrast to arm inductance and smoothing reactor, L F C L will be bypassed via parallel-connected thyristors after blocking converter to prevent the effect on fault interruption speed. R F C L shares the stress on energy absorption device (metal oxide arrester) to facilitate fault interruption. The DCCB requirement in interruption capacity and breaking speed can be satisfied effortlessly through the EFCLC. The working principle and parameter determination of the EFCLC are presented in detail, and its effectiveness is verified by simulation in RT-LAB and MATLAB software platforms.

Energy absorption of thin-walled square tubes designed by kirigami approach

Thin-walled tubes are extensively employed as energy absorption devices. The extensional mode (EM) of collapse in thin-walled square tube is desirable in terms of energy absorption while facing impact loading. In this paper, a novel tube known as the kirigami crash box (KCB) that is designed by kirigami approach, is proposed to improve the crashworthiness of the tubular structures by collapsing in EM. The experimental and numerical results show that kirigami pattern in KCB serves as both geometric imperfection to reduce the initial peak force Fmax and mode inducer to trigger the desired EM while collapsing. Numerical simulation indicates that the ideal EM is successfully triggered with a 39.7% reduction of initial peak force Fmax and 33.9% increase of mean crushing force Fm comparing to conventional square tube (N-CST). Parametric study shows that the collapse mode of KCBs deformed in EM is independent of aspect ratio b/t within the range of b/t ≤ 81.3, while for CST, the corresponding range is b/t ≤ 7.5. KCB inclines to collapse in EM when the dihedral angle θ or the number of modules M decrease. The Fmax, Fm and CFEs of KCBs with identical M increase with the increasing θ. Whereas, the effect of M on energy absorption is relatively less important while θ remains the same. Moreover, the superiority of energy absorption for KCB subjected to dynamic loading is more significant comparing to quasi-static axial crushing.