Monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading

Biomechanics of bone has drawn major concern in research due to social and economic demand. In real life, trabecular bone is subjected to multiaxial stresses during routine physiological loading. Fatigue failure of the bone accounts for various clinical implications, thus studies and research to bet...

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Main Author:	Mohd. Szali Januddi, Mohd. Al-Fatihhi
Format:	Thesis
Language:	English
Published:	2015
Subjects:	TJ Mechanical engineering and machinery
Online Access:	http://eprints.utm.my/id/eprint/77731/1/MohdALFatihhiMohdPFKM2015.pdf
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id	my-utm-ep.77731
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spelling	my-utm-ep.777312018-06-29T21:45:18Z Monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading 2015-12 Mohd. Szali Januddi, Mohd. Al-Fatihhi TJ Mechanical engineering and machinery Biomechanics of bone has drawn major concern in research due to social and economic demand. In real life, trabecular bone is subjected to multiaxial stresses during routine physiological loading. Fatigue failure of the bone accounts for various clinical implications, thus studies and research to better understand the fatigue failure of the bone are needed. The overall aim of this study is to investigate the effect of torsional loading towards trabecular behaviour under compression in both monotonic and fatigue loading. Samples from femoral bovine trabecular bone were subjected to a series of monotonic and cyclic tests. Hill’s criterion was selected to determine the five combined stress ratio of compressive to shear stress for fatigue test. For finite element simulation, effect of morphology and orientation were investigated to predict fatigue life and plastic strain. The ultimate stress of the trabecular bone in monotonic compression and torsion were 14.22 and 8.95 MPa, respectively. In monotonic multiaxial loading, the ultimate stress was reduced to 2.5 MPa in compression and 3.8 MPa in torsion. Under fatigue compression, an endurance limit was found approximately at 25 % of ultimate compressive stress. Under multiaxial fatigue, the ability of the sample to retain shear stiffness with increased number of cycles is strongly correlated to the stress ratio. Fatigue life reduction was significant when the maximum shear stress is at least 24 % of the maximum compression stress. From the computational analysis, it was demonstrated that lower bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and connectivity density (Conn.D) resulted in lower number of cycles to failure, regardless to the loading conditions. However, the number of cycles to failure was found to be negatively correlated to the value of structural model index (SMI). Off-axis orientation effect on the fatigue life of the trabecular bone was demonstrated the worst in horizontal trabecular bone model. In conclusion, the effect of torsional loading onto the mechanical behaviour of bovine trabecular bone was demonstrated throughout this study. It is apparent that torsional forces are the major factor that needs to be considered since these can lead to fatigue fractures. This research is expected to improve the knowledge base for the development of trabecular bone analogous materials. 2015-12 Thesis http://eprints.utm.my/id/eprint/77731/ http://eprints.utm.my/id/eprint/77731/1/MohdALFatihhiMohdPFKM2015.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:96582 phd doctoral Universiti Teknologi Malaysia, Faculty of Mechanical Engineering Faculty 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 Mohd. Szali Januddi, Mohd. Al-Fatihhi Monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading
description	Biomechanics of bone has drawn major concern in research due to social and economic demand. In real life, trabecular bone is subjected to multiaxial stresses during routine physiological loading. Fatigue failure of the bone accounts for various clinical implications, thus studies and research to better understand the fatigue failure of the bone are needed. The overall aim of this study is to investigate the effect of torsional loading towards trabecular behaviour under compression in both monotonic and fatigue loading. Samples from femoral bovine trabecular bone were subjected to a series of monotonic and cyclic tests. Hill’s criterion was selected to determine the five combined stress ratio of compressive to shear stress for fatigue test. For finite element simulation, effect of morphology and orientation were investigated to predict fatigue life and plastic strain. The ultimate stress of the trabecular bone in monotonic compression and torsion were 14.22 and 8.95 MPa, respectively. In monotonic multiaxial loading, the ultimate stress was reduced to 2.5 MPa in compression and 3.8 MPa in torsion. Under fatigue compression, an endurance limit was found approximately at 25 % of ultimate compressive stress. Under multiaxial fatigue, the ability of the sample to retain shear stiffness with increased number of cycles is strongly correlated to the stress ratio. Fatigue life reduction was significant when the maximum shear stress is at least 24 % of the maximum compression stress. From the computational analysis, it was demonstrated that lower bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and connectivity density (Conn.D) resulted in lower number of cycles to failure, regardless to the loading conditions. However, the number of cycles to failure was found to be negatively correlated to the value of structural model index (SMI). Off-axis orientation effect on the fatigue life of the trabecular bone was demonstrated the worst in horizontal trabecular bone model. In conclusion, the effect of torsional loading onto the mechanical behaviour of bovine trabecular bone was demonstrated throughout this study. It is apparent that torsional forces are the major factor that needs to be considered since these can lead to fatigue fractures. This research is expected to improve the knowledge base for the development of trabecular bone analogous materials.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Mohd. Szali Januddi, Mohd. Al-Fatihhi
author_facet	Mohd. Szali Januddi, Mohd. Al-Fatihhi
author_sort	Mohd. Szali Januddi, Mohd. Al-Fatihhi
title	Monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading
title_short	Monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading
title_full	Monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading
title_fullStr	Monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading
title_full_unstemmed	Monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading
title_sort	monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading
granting_institution	Universiti Teknologi Malaysia, Faculty of Mechanical Engineering
granting_department	Faculty of Mechanical Engineering
publishDate	2015
url	http://eprints.utm.my/id/eprint/77731/1/MohdALFatihhiMohdPFKM2015.pdf
_version_	1747817817869123584

Monotonic and cyclic behaviour of trabecular bone under uniaxial and multiaxial loading

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