Over the past several decades, a noticeable amount of research efforts has been directed to minimising injuries and death to people inside a structure that is subjected to an impact loading. Thin-walled (TW) tubular components have been widely employed in energy absorbing structures to alleviate the detrimental effects of an impact loading during a collision event and thus enhance the crashworthiness performance of a structure. Comprehensive knowledge of the material properties and the structural behaviour of various TW components under various loading conditions is essential for designing an effective energy absorbing system. In this paper, based on a broad survey of the literature, a comprehensive overview of the recent developments in the area of crashworthiness performance of TW tubes is given with a special focus on the topics that emerged in the last ten years such as crashworthiness optimisation design and energy absorbing responses of unconventional TW components including multi-cells tubes, functionally graded thickness tubes and functionally graded foam filled tubes. Due to the huge number of studies that analysed and assessed the energy absorption behaviour of various TW components, this paper presents only a review of the crashworthiness behaviour of the components that can be used in vehicles structures including hollow and foam-filled TW tubes under lateral, axial, oblique and bending loading.

https://myresearchspace.uws.ac.uk/ws/files/1765038/Paper_2.pdf

On the crashworthiness performance of thin-walled energy absorbers: Recent advances and future developments

New types of trigger and multi-cell profiles with four square elements at the corner are developed. In terms of the crash energy absorption and weight efficiency, the new multi-cell structure shows dramatic improvements over the conventional square box column. The optimization process with the target of maximizing the specific energy absorption has been successfully carried out, and the example of design process is provided. In the optimization process, the problem of stable progressive folding is also addressed. The analytical solution for calculating the mean crushing force of new multi-cell profiles is derived showing good agreement with the numerical results. Finally, the advantage of the new design over the conventional single or multi-cell profiles is discussed.

New extruded multi-cell aluminum profile for maximum crash energy absorption and weight efficiency

Optimization for structural crashworthiness and energy absorption has become an important topic of research attributable to its proven benefits to public safety and social economy. This paper provides a comprehensive review of the important studies on design optimization for structural crashworthiness and energy absorption. First, the design criteria used in crashworthiness and energy absorption are reviewed and the surrogate modeling to evaluate these criteria is discussed. Second, multiobjective optimization, optimization under uncertainties and topology optimization are reviewed from concepts, algorithms to applications in relation to crashworthiness. Third, the crashworthy structures are summarized, from generically novel structural configurations to industrial applications. Finally, some conclusions and recommendations are provided to enable academia and industry to become more aware of the available capabilities and recent developments in design optimization for structural crashworthiness and energy absorption.

On design optimization for structural crashworthiness and its state of the art

Foam-filled thin-wall structures have exhibited significant advantages in light weight and high energy absorption and been widely applied in automotive, aerospace, transportation and defence industries. Unlike existing uniform foam materials, this paper introduces functionally graded foam (FGF) fillers to fill thin-walled structures, aiming to improve crashworthiness. In this novel structure, the foam density varies throughout the depth in a certain gradient. Numerical simulations showed that gradient exponential parameter m that controls the variation of foam density has significant effect on system crashworthiness. In this study, the single and multiobjective particle swarm optimization methods are used to seek for optimal gradient, where response surface models are established to formulate specific energy absorption and peak crushing force. The results yielded from the optimizations indicate that the FGF material is superior to its uniform counterparts in overall crashworthiness. The data has considerable implication in design of FGF materials for optimizing structural crashworthiness.

Crashworthiness design for functionally graded foam-filled thin-walled structures

Multi-cell metal columns were found to be much more efficient in energy absorption than single-cell columns under axial compression. However, the experimental investigations and theoretical analyses of them are relatively few. In this paper, the quasi-static axial compression tests are carried out for multi-cell columns with different sections. The significant advantage of multi-cell sections over single cell in energy absorption efficiency is investigated and validated. Numerical simulations are also conducted to simulate the compression tests and the numerical results show a very good agreement with experiment. Theoretial analyses based on constitutive element method are proposed to predict the crush resistance of multi-cell columns and the theoretical predictions compare very well with the experimental and numerical results.

Energy absorption of multi-cell stub columns under axial compression

Crush behavior of thin-walled prismatic columns under combined bending and compression

This paper addresses a design aspect of a front side rail structure of an automobile body from the point of view of weight efficiency and crush energy absorption. Various orientations of the cross-section and ways of reinforcing the cross-section by an internal stiffening member are investigated. The specific energy absorption (i.e. energy absorption per unit weight) is taken as a measure of the performance of a structure. Also the advantages of reinforcing the side rail by means of aluminum foam filling are assessed. It is shown through extensive numerical simulation using nonlinear finite element code PAM–CRASH, that the model with a diagonally positioned internal stiffener and suitable triggering dents can absorb up to 200% more energy than the typical double-hat/double-cell profile member. At the same time there is a 3 fold increase in the specific energy absorption. By using the concept of aluminum foam-filling with 3 MPa foam, the specific energy absorption increases by a factor of 2.84.

Heung-Soo Kim

Papers

New extruded multi-cell aluminum profile for maximum crash energy absorption and weight efficiency

Crush behavior of thin-walled prismatic columns under combined bending and compression

Effect of the cross-sectional shape of hat-type cross-sections on crash resistance of an “S”-frame

Numerical and analytical study on deep biaxial bending collapse of thin-walled beams

Closed-form solution for crushing response of three-dimensional thin-walled “S” frames with rectangular cross-sections