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Investigating the Biomechanics of a Lizard Skull Using Advanced Computer Modelling Techniques with Experimental Validation

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Investigating the Biomechanics of a Lizard Skull Using Advanced Computer Modelling Techniques with Experimental Validation INVESTIGATING THE BIOMECHANICS OF A LIZARD SKULL USING ADVANCED COMPUTER MODELLING TECHNIQUES WITH EXPERIMENTAL VALIDATION Being a Thesis submitted for the Degree of PhD In the University of Hull By Mehran Moazen, BSc (Hons) December 2008 Dedicated to my parents Table of contents Abstract Acknowledgements Contents…………………………………………………………………i Chapter 1: Introduction ......................................................................... 1 1.1 Overview............................................................................................................ 1 1.2 Model creation: geometry .................................................................................. 4 1.3 Biomechanical modelling .................................................................................. 5 1.3.1 Musculoskeletal modelling ......................................................................... 5 1.3.2 Finite element modelling ............................................................................ 7 1.4 Experimental validation study ........................................................................... 7 1.5 Methodology ...................................................................................................... 8 1.6 Goals of project.................................................................................................. 9 1.7 Chapter organization.......................................................................................... 9 Chapter 2: Lizard anatomy.................................................................. 11 2.1 Introduction...................................................................................................... 11 2.2 General comments on lizards........................................................................... 11 2.3 Morphological evolution.................................................................................. 14 2.3.1 Temporal openings.................................................................................... 14 2.3.2 Cranial kinesis........................................................................................... 15 2.4 Uromastyx ........................................................................................................ 17 2.4.1 Why is Uromastyx interesting? ................................................................. 17 2.4.2 Lifestyle..................................................................................................... 17 2.4.3 The dentition ............................................................................................. 18 2.4.4 Cranial anatomy ........................................................................................ 18 i 2.4.5 Cranial joints............................................................................................. 18 2.4.6 Cranial muscles and ligaments.................................................................. 21 2.4.6.1 Muscle................................................................................................ 21 2.4.6.2 Ligaments........................................................................................... 22 2.4.7 Feeding...................................................................................................... 23 2.5 Discussion ........................................................................................................ 24 Chapter 3: Literature review............................................................... 25 3.1 Introduction...................................................................................................... 25 3.2 Bone ................................................................................................................. 25 3.2.1 Bone structure ........................................................................................... 27 3.2.2 Mechanical properties of bone.................................................................. 28 3.2.2.1 Cortical bone analysis ........................................................................ 29 3.2.2.2 Cancellous bone analysis ................................................................... 30 3.3 Sutures.............................................................................................................. 31 3.3.1 Microscopic and macroscopic morphology of sutures.............................. 32 3.3.2 Mechanical property of sutures................................................................. 33 3.4 Muscles ............................................................................................................ 35 3.4.1 Skeletal muscle structure .......................................................................... 35 3.4.2 Mechanical properties of muscles............................................................. 37 3.4.2.1 Active and passive length-tension...................................................... 38 3.4.2.2 Force-velocity .................................................................................... 41 3.5 Experimental electromyography, cineradiography and bite force analysis ..... 43 3.6 Strain gauge analysis........................................................................................ 45 3.7 Free body diagram analysis and computer modelling of mastication.............. 50 3.7.1 Free body diagram analysis....................................................................... 50 3.7.2 Basic computer model............................................................................... 52 ii 3.7.3 Multi-body dynamic analysis.................................................................... 54 3.8 Finite element analysis of skulls ...................................................................... 58 3.9 Combined dynamic and finite element analysis of mastication....................... 66 Chapter 4: Dynamic analysis of a lizard skull ................................... 68 4.1 Introduction...................................................................................................... 68 4.2 Overview of ADAMS ...................................................................................... 68 4.3 MDA modelling of a Uromastyx skull............................................................. 69 4.3.1 Study 1: Basic model development........................................................... 70 4.3.1.1 Method ............................................................................................... 70 4.3.1.2 Results................................................................................................ 74 4.3.1.3 Discussion .......................................................................................... 79 4.3.2 Study 2: Accurate geometry model........................................................... 81 4.3.2.1 Method ............................................................................................... 81 4.3.2.2 Results................................................................................................ 86 4.3.2.3 Discussion .......................................................................................... 90 4.3.3 Study 3: Accurate muscle model............................................................... 93 4.3.3.1 Method ............................................................................................... 93 4.3.3.2 Results................................................................................................ 97 4.3.3.3 Discussion ........................................................................................ 100 4.4 Discussion ...................................................................................................... 101 Chapter 5: Finite element analysis of a lizard skull ........................ 104 5.1 Introduction.................................................................................................... 104 5.2 Overview of ANSYS ..................................................................................... 104 5.3 FEA modelling of a Uromastyx skull............................................................. 105 5.3.1 Study 1: FEA vs. combined FEA and MDA........................................... 105 5.3.1.1 Method ............................................................................................. 105 iii 5.3.1.2 Results.............................................................................................. 109 5.3.1.3 Discussion ........................................................................................ 111 5.3.2 Study 2: FEA modelling of biting........................................................... 112 5.3.2.1 Method ............................................................................................. 112 5.3.2.2 Results.............................................................................................. 113 5.3.2.3 Discussion ........................................................................................ 121 5.3.3 Study 3: Suture modelling....................................................................... 124 5.3.3.1 Method ............................................................................................. 124 5.3.3.2 Results.............................................................................................. 126 5.3.3.3 Discussion ........................................................................................ 134 5.3.4 Study 4: The role of the quadrate and temporal bar................................ 138 5.3.4.1 Method ............................................................................................
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