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

Crashworthiness analysis and design of multi-cell hexagonal columns under multiple loading cases

Energy absorption of metal, composite and metal/composite hybrid structures under oblique crushing loading

Crashworthiness of vertex based hierarchical honeycombs in out-of-plane impact

This paper treats the dynamic response and energy absorption of aluminum foamfilled
conical tubes under axial impact loading using non-linear finite element
techniques. The influence of geometrical, material and loading parameters on the impact
response is investigated using validated numerical models. Results are quantified in
terms of important impact response parameters and indicate that the foam filler
stabilizes the crushing process and thus improves the energy absorption capacity. The
superior performance of foam-filled conical tubes as impact energy absorbers is evident
from the results. The research information generated will be useful in developing
guidance towards the design of these devices in impact applications.

Dynamic computer simulation and energy absorption offoam-filled conical tubes under axial impact loading

Crushing analysis and multiobjective optimization for functionally graded foam-filled tubes under multiple load cases

This paper provides a comparative study on the crashworthiness of different functionally-graded thin-wall tubes under multiple loading angles, which include hollow uniform thickness (H-UT), hollow functionally graded thickness (H-FGT), foam-filled uniform thickness (F-UT) and foam-filled functionally graded thickness (F-FGT) configurations. First, finite element analyses of these differently graded circular tubes reveal that the F-FGT tube has the best crashworthiness under multiple loading angles. Second, parametric study on the F-FGT tube indicates that the thickness gradient and variation range significantly influence its crashworthiness. Third, the Non-dominated Sorting Genetic Algorithm (NSGA-II) is used to optimize the F-FGT tube, in which the optimal thickness variation is sought for maximizing specific energy absorption (SEA) and minimizing initial peak force (IPF) under multiple loading angles. The optimized F-FGT tube exhibits better crashworthiness than other three equivalent tube configurations, indicating that the F-FGT tube can be a potential energy absorber when oblique impact loading is inevitable.

Comparison of functionally-graded structures under multiple loading angles

Effectiveness of a raised road: rail crossing for the safety of road vehicle occupants

The safety of cars and trucks crossing gapped road surfaces can be affected by their operational speed, mass, and the tire and road surface characteristics. As part of a research on the safety of road vehicles crossing discontinuous road surfaces, the dynamic behavior of a single tire passing a gap has been examined as reported in this paper. First, the kinematics of a tire crossing the gap in the road surface is analytically formulated. The formulation has shown that the tire exhibits three distinct (single-point, two-point, and flying) modes of travel depending on its operational speed. The dynamics of the tire are larger in single-point mode that exhibits two critical velocities, which have been validated using a nonlinear arbitrary Lagrangian Eulerian method in the finite-element framework. The validated analytical model has shown that the critical velocity is mainly affected by the mass of the overburden. Introduction

Dynamics of tire crossing on a gapped road surface

A hand-pressed self-rotation type screwdriver comprises a one-way mechanism, a ball screw mechanism, a returning mechanism, a (an) lower casing/upper casing and an organic sleeve. The one-way mechanism is provided with an inner pipe fitting, a limiting conduit, a pair of steel balls, a lower spring and a rear press cover. The ball screw mechanism comprises a screw and a pair of steel balls. The returning mechanism comprises two springs. By pressing the rear press cover and the screw, the screw can be obliged to carry out helical motion relative to a casing so as to achieve the effect of tightening or dismantling the screw; when pressure is removed, the returning mechanism can oblige every mechanism to return; and when the screw is tightened, only extrusion motion needs to be performed through the hand-pressed self-rotation type screwdriver, and the effects of time saving and convenience are achieved.

Zheshuo Zhang

Papers

Crushing analysis and multiobjective optimization for functionally graded foam-filled tubes under multiple load cases

Comparison of functionally-graded structures under multiple loading angles

Effectiveness of a raised road: rail crossing for the safety of road vehicle occupants

Dynamics of tire crossing on a gapped road surface

Hand-pressed self-rotation type screwdriver