Crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings

Filling thin-walled tubes with foam cores is a typical method to promote a desirable energy absorption performance and stabilize the crushing responses of thinwalled tubes under impact loading. Auxetic foams as new class of cellular materials have recently gained popularity within the research commu...

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Main Author:	Mohsenizadeh, Saeid
Format:	Thesis
Language:	English
Published:	2019
Subjects:	TJ Mechanical engineering and machinery
Online Access:	http://eprints.utm.my/id/eprint/102123/1/SaeidMohsenizadehPSKM2019.pdf.pdf
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spelling	my-utm-ep.1021232023-08-05T02:41:23Z Crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings 2019 Mohsenizadeh, Saeid TJ Mechanical engineering and machinery Filling thin-walled tubes with foam cores is a typical method to promote a desirable energy absorption performance and stabilize the crushing responses of thinwalled tubes under impact loading. Auxetic foams as new class of cellular materials have recently gained popularity within the research community due to their enhanced mechanical properties. However, the energy absorption performance of auxetic foamfilled tubes design information is very limited. The aim of this study is to evaluate the crush response, the energy absorption capacity and the deformation behavior of auxetic foam-filled square and circular tubes under quasi-static and dynamic axial loadings. For comparison, energy absorption performance of empty and conventional foamfilled square and circular tubes was also experimentally and numerically examined with respect to deformation modes and load-displacement responses. All tube specimens were crushed at a constant loading rate of 3 mm/min for quasi-static loading and an initial impact velocity of 5 m/s was adopted for dynamic loading. In order to investigate the influence of tube effective parameters such as wall thickness, diameter, width and height, a series of parametric studies were conducted using validated finite element (FE) models. The initial finding reveals that both auxetic foam-filled square and circular tubes are superior to empty and conventional foam-filled tubes in terms of energy absorption capacity without a significant increase in the initial peak load. From the initial finding and due to the great potential of auxetic foam as cores, a new fabrication technique called Quasi Tri-axial Compression Method (QTCM) was developed to fabricate the auxetic foam with the maximum achievable negative Poisson’s ratio. The fabricated auxetic foam with optimal re-entrancy was then introduced as the core for the tubes. Moreover, energy absorption capacity of auxetic foam-filled tubes was experimentally quantified with the foam Poisson’s ratio ranging from -0.13 to -0.32. The results show that the energy absorbed by auxetic foam-filled square and circular tubes loaded dynamically are approximately 34.7% and 22% greater than that of conventional foam-filled square and circular tubes respectively. This is practically beneficial when higher kinetic energy needs to be absorbed in order to reduce the impact force transmitted to the occupant’s compartment. Furthermore, it is evident that an increase in the auxeticity level of foam filler enhances crashworthiness performance of filled tubes under both quasi-static and dynamic loading conditions. Above all, the primary outcome of this thesis is a design guideline for the use of an auxetic foam as a core for energy absorbing devices where axial impact loading is anticipated. 2019 Thesis http://eprints.utm.my/id/eprint/102123/ http://eprints.utm.my/id/eprint/102123/1/SaeidMohsenizadehPSKM2019.pdf.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:145019 phd doctoral Universiti Teknologi Malaysia Faculty of Engineering - School of Mechanical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TJ Mechanical engineering and machinery
spellingShingle	TJ Mechanical engineering and machinery Mohsenizadeh, Saeid Crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings
description	Filling thin-walled tubes with foam cores is a typical method to promote a desirable energy absorption performance and stabilize the crushing responses of thinwalled tubes under impact loading. Auxetic foams as new class of cellular materials have recently gained popularity within the research community due to their enhanced mechanical properties. However, the energy absorption performance of auxetic foamfilled tubes design information is very limited. The aim of this study is to evaluate the crush response, the energy absorption capacity and the deformation behavior of auxetic foam-filled square and circular tubes under quasi-static and dynamic axial loadings. For comparison, energy absorption performance of empty and conventional foamfilled square and circular tubes was also experimentally and numerically examined with respect to deformation modes and load-displacement responses. All tube specimens were crushed at a constant loading rate of 3 mm/min for quasi-static loading and an initial impact velocity of 5 m/s was adopted for dynamic loading. In order to investigate the influence of tube effective parameters such as wall thickness, diameter, width and height, a series of parametric studies were conducted using validated finite element (FE) models. The initial finding reveals that both auxetic foam-filled square and circular tubes are superior to empty and conventional foam-filled tubes in terms of energy absorption capacity without a significant increase in the initial peak load. From the initial finding and due to the great potential of auxetic foam as cores, a new fabrication technique called Quasi Tri-axial Compression Method (QTCM) was developed to fabricate the auxetic foam with the maximum achievable negative Poisson’s ratio. The fabricated auxetic foam with optimal re-entrancy was then introduced as the core for the tubes. Moreover, energy absorption capacity of auxetic foam-filled tubes was experimentally quantified with the foam Poisson’s ratio ranging from -0.13 to -0.32. The results show that the energy absorbed by auxetic foam-filled square and circular tubes loaded dynamically are approximately 34.7% and 22% greater than that of conventional foam-filled square and circular tubes respectively. This is practically beneficial when higher kinetic energy needs to be absorbed in order to reduce the impact force transmitted to the occupant’s compartment. Furthermore, it is evident that an increase in the auxeticity level of foam filler enhances crashworthiness performance of filled tubes under both quasi-static and dynamic loading conditions. Above all, the primary outcome of this thesis is a design guideline for the use of an auxetic foam as a core for energy absorbing devices where axial impact loading is anticipated.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Mohsenizadeh, Saeid
author_facet	Mohsenizadeh, Saeid
author_sort	Mohsenizadeh, Saeid
title	Crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings
title_short	Crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings
title_full	Crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings
title_fullStr	Crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings
title_full_unstemmed	Crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings
title_sort	crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings
granting_institution	Universiti Teknologi Malaysia
granting_department	Faculty of Engineering - School of Mechanical Engineering
publishDate	2019
url	http://eprints.utm.my/id/eprint/102123/1/SaeidMohsenizadehPSKM2019.pdf.pdf
_version_	1776100851231752192

Crashworthiness performance of optimized auxetic foamfilled tubes under axial loadings

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