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عدد المساهمات : 18994 التقييم : 35488 تاريخ التسجيل : 01/07/2009 الدولة : مصر العمل : مدير منتدى هندسة الإنتاج والتصميم الميكانيكى
| موضوع: رسالة ماجستير بعنوان Design of a suspension system for a formula student race car السبت 14 نوفمبر 2020, 5:06 pm | |
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أخوانى فى الله أحضرت لكم رسالة ماجستير بعنوان Design of a suspension system for a formula student race car by Ingi Níels Karlsson Thesis of 60 ECTS credits submitted to the School of Science and Engineering at Reykjavík University in partial fulfillment of the requirements for the degree of Master of Science (M.Sc.) in Mechanical Engineering June 2018 Supervisor: Indriði Sævar Ríkharðsson, Supervisor Assistant Professor, Reykjavík University, Iceland Examiner: Dr. Rúnar Unnþórsson, Examiner Professor, University of Iceland, Iceland
و المحتوى كما يلي :
Contents Acknowledgements xi Contents xii List of Figures xiv List of Tables xvi List of Abbreviations xvii List of Symbols xix 1 Introduction 1 1.1 Background 1 1.2 Design Constraints 2 1.3 FS rules 3 1.4 Objective . 3 1.5 Thesis structure 4 2 Research 5 2.1 Types of suspension systems . 5 2.2 Suspension properties . 5 2.2.1 Kingpin inclination 5 2.2.2 Caster . 5 2.2.3 Camber 6 2.2.4 Scrub radius . 7 2.2.5 Wheel rate 7 2.2.6 Roll rate 9 3 Design process 11 3.1 Identification of relevant rules 12 3.2 Identification of team constraints . 12 3.3 Preliminary design 12 3.3.1 A-arms 12 3.3.2 Push rods . 13 3.3.3 Bell cranks 15 3.3.4 Spring and damper 15 3.3.5 Anti roll bar 15 3.4 Adams . 18 3.4.1 Introduction 18 xii3.4.2 Adams Car model 19 3.4.3 Adams Car simulations 20 3.4.4 Results from Adams Car . 22 3.5 3D modeling . 25 3.5.1 A-arms 25 3.5.2 Pushrods . 27 3.5.3 Bell cranks 28 3.5.4 Anti-roll bar . 29 4 Manufacturing 31 5 Conclusion 39 6 Future work 41 Bibliography 43 A Datasheets 45 A.1 Aluminum 6061 T6 45 A.2 Aluminum 7075 T6 49 A.3 303 Stainless Steel 55 A.4 Structural steel S235 . 58 A.5 Structural steel S355 . 61 A.6 Öhlins TTX25 Mk II spring dimensions . 64 A.7 Öhlins TTX25 Mk II internal schematic . 66 A.8 Öhlins TTX25 Mk II external dimensions 70 A.9 Öhlins TTX25 Mk II dyno plot 72 A.10 Fluro spherical bearing 76 A.11 Fluro spherical bearing rod end 78 A.12 SKF 608-2RSH 80 B Drawings 83 C Tables and calculations 127 C.1 Hard point table 127 C.2 Results from Adams Car . 131 C.2.1 Summary of forces 131 C.2.2 Pothole simulation 133 C.2.3 Plank simulation . 147 C.2.4 Constant radius cornering simulation 161 C.2.5 Tilt simulation 175 C.2.6 Front parallel wheel travel simulation 189 C.2.7 Rear parallel wheel travel simulation 199List of Figures 1.1 The 2017 car at Silverstone after the competition 2 2.1 Kingpin inclination and caster angles . 6 2.2 Camber angle . 6 2.3 Sprung mass and unsprung mass definition 8 2.4 The roll center is found by drawing lines between the center of the tire patch to instantaneous centers 9 3.1 Design flow chart . 11 3.2 Proposed A-arm design 13 3.3 Push and pull rod suspension [8] . 13 3.4 Force on the pushrod with 600 N force on the wheel . 14 3.5 Free body diagram of the forces acting on the pushrod 14 3.6 Cutaway model of the Öhlins TTX25 MkII FS damper [9] . 16 3.7 Öhlins TTX 25 MkII internal schematic [11] . 16 3.8 Adams Car[4] design flowchart 18 3.9 Two body position mechanism [12] . 19 3.10 Adams Car [4] 3D model of the formula student car . 20 3.11 Adams Car [4] suspension points table 20 3.12 Adams Car [4] part modification window. The preliminary Inventor model was used to define the mass and properties of each part in the Adams model . 21 3.13 Adams Car [4] part modification window 21 3.14 Adams Car [4] parallel wheel travel simulation setup window 22 3.15 Adams Car [4] postprocessing window parallel wheel travel simulation camber change results . 22 3.16 Adams Car [4] constant cornering simulation with wheel forces in red on the picture . 23 3.17 Adams Car [4] parallel wheel travel simulation of the front suspension system with wheel forces in red on the picture 23 3.18 Adams Car [4] parallel wheel travel simulation motion ratio of the spring and damper versus the wheel . 24 3.19 Inventor [14] hard point 3D model 25 3.20 Front upper control arm 3D model from Inventor [14] 26 3.21 Front upper control arm FEA results and a free body diagram showing location of whee the force of 3748.9 N is applied . 26 3.22 Front push rod assembly 3D model from Inventor [14] . 27 3.23 Buckling end conditions constants [17] 27 3.24 Front bell crank 3D model from Inventor [14] 28 xiv3.25 Front bell crank FEA results and a free body diagram showing location of where the force of 3748.9 N is applied 29 3.26 Front suspension assembly 3D model from Inventor [14] 29 4.1 Sleipnir’s workspace at the university workshop . 31 4.2 The university workshop . 32 4.3 Laser cut brackets for the suspension, first from left is the insert for the rear arm of the A-arms, second from left is the push rod mount bracket for the A-arms, third and fourth from left are mounting brackets for the A-arms to the chassis 33 4.4 Spherical bearing seat for the control arms 33 4.5 Spherical bearing seat toolpath from Inventor HSM [18] 34 4.6 Inserts for spherical rod ends . 35 4.7 Spacer for spherical rod ends to increase the travel angle of the rod end 35 4.8 Spacer for spherical rod ends toolpath from Inventor HSM [18] . 36 4.9 Inserts welded to A-arm 36 4.10 Front A-arms mounted on the chassis 37 4.11 Bell crank machined front side 38 4.12 Bell crank machined back side 38 5.1 Final 3D model of the suspension assembly in Inventor [14] 39 C.1 Adams car [4] pothole simulation setup window . 133 C.2 Adams car [4] plank simulation setup window 147 C.3 Adams car [4] constant corner simulation setup window . 161 C.4 Adams car [4] tilt table simulation setup window 175 C.5 Adams car [4] parallel wheel travel simulation setup window 189 C.6 Adams car [4] parallel wheel travel simulation setup window 199List of Tables 3.1 Static setup of the suspension . 24 3.2 Forces from Adams Car [4] simulations 24 5.1 Comparison of weight of left side suspension components between 2017 and 2018 car 40 xviList of Abbreviations RU Reykjavík University FS Formula Student SAE Society of Automotice Engineers US United States UK United Kingdom FSAE Formula SAE FSG Formula Student Germany IMechE Institution of Mechanical Engineers MIRA Motor Industry Research Association CNC Computer numerical control MDS Multibody Dynamics Simulation CoG Center of Gravity RC Roll Center SF Safety Factor CAD Computer Aided Design FEA Finite element analysis List of Symbols Symbol Description Value/Units Ks Spring rate N m−1 KT Tire spring rate N m−1 Kw Wheel rate N m−1 M Mass kg MR Motion ratio F Force N f Frequency Hz Ms Sprung mass kg M us Unsprung mass kg l Length m Φ r/Ay Roll gradient deg/g g Acceleration 9.81m s−2 H Distance from roll center to CoG m KΦF Front roll rate Nm/deg KΦR Rear roll rate Nm/deg tf Front track width m tr Rear track width m KLF Left front wheel rate N/m KLR Right front wheel rate N/m KLR Left rear wheel rate N/m KRR Right rear wheel rate N/m KΦA Total anti roll bar rate needed Nm/deg tA Average track m KΦdes Desired total roll stiffness Nm/deg MA−arm Moment around the A-arm mount to the chassis Nm Fwheel Normal forces on the wheel center N L Length m FN Normal force N θ Angle deg Fpushrod Force acting on the push rod N MARB Torque on the anti roll bar Nm FARB Force on anti roll bar arm N x Length m θ Rotation of the anti roll bar deg G Modulus of rigidity GPa J0 Polar moment of inertia mm4 FARB/θ Anti-roll bar torsional stiffness N/degC Buckling end condition E Young’s modulus GPa D outer diameter m d inner diameter m
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