FE analysis of a dog clutch for trucks with all-wheel-drive FE-analys av en klokoppling för allhjulsdrivna lastbilar Växjö, 2010-05-28 15p Mechanical Engineering/4MT01E Handledare: Hans Hansson, SwePart Transmission AB Handledare: Andreas Linderholt, Linnéuniversitetet, Institutionen för teknik Examinator: Anders Karlsson, Linnéuniversitetet, Institutionen för teknik Thesis nr: TEK 054/2010 Författare: Mattias Andersson, Kordian Goetz Organisation/ Organization Författare/Author(s) Linnéuniversitetet Mattias Andersson, Kordian Goetz Institutionen för teknik Linnaeus University School of Engineering Dokumenttyp/Type of Document Handledare/tutor Examinator/examiner Examensarbete/Master Thesis Andreas Linderholt Anders Karlsson Titel och undertitel/Title and subtitle FE-analys av en klokoppling för allhjulsdrivna lastbilar / FE analysis of a dog clutch for trucks with all-wheel-drive Sammanfattning (på svenska) Examensarbetet är utfört för att försöka förbättra inkopplingen av allhjulsdrift på lastbilar. När en lastbil kör på halt eller löst väglag kan hjulspinn uppstå vid bakhjulen. Om föraren kopplar in allhjulsdriften när hjulen börjat slira uppstår en relativ rotationshastighet mellan halvorna i klokopplingen. Om denna relativa rotationshastighet är för hög kommer halvorna i kopplingen studsa mot varandra innan de kopplas ihop eller inte koppla ihop alls. För att undvika detta problem har klokopplingens tandgeometri modifierats. FE simuleringar är gjorda på den ursprungliga modellen samt alla nya modeller för att ta reda på vilken som kopplar vid högst relativa rotationshastighet. Resultaten visar att förbättringar kan göras. Enkla modifieringar på avfasningarnas avstånd och vinklar visar att klokopplingen kan klara upp till 120 rpm i relativ rotationshastighet jämfört med den ursprungliga modellen som endast klarar 50 rpm. Nyckelord Klokoppling, Allhjulsdrift, FE-analys Abstract (in English) The thesis is carried out in order to improve the transfer case in trucks with all-wheel-drive. When the truck loses traction at the rear wheels, due to slippery surfaces, wheel-spin occurs. If the driver engages the all-wheel-drive at a point where traction already has been lost, a relative rotational speed in the dog clutch will occur. If this relative speed is too high the dog clutch bounces of itself before coupling or it does not couple at all. To avoid this problem, the geometry of the teeth is modified. FE simulations are done for the existing model as well as for all the new models in order to find out which of them can handle the highest relative rotational speed. The results show that the original model is not the best one. Simple modifications of the teeth’s chamfer distance and chamfer angle shows that the dog clutch can handle up to 120 rpm of relative rotational speed whereas the original model only handles 50 rpm. Key Words Gleason type curvic coupling, Dog clutch, All-wheel-drive, FE analysis Utgivningsår/Year of issue Språk/Language Antal sidor/Number of pages 2010 English 70 Internet/WWW Abstract The thesis is carried out in order to improve the transfer case in trucks with all-wheel-drive. When the truck loses traction at the rear wheels, due to slippery surfaces, wheel-spin occurs. If the driver engages the all-wheel-drive at a point where traction already has been lost, a relative rotational speed in the dog clutch will occur. If this relative speed is too high the dog clutch bounces of itself before coupling or it does not couple at all. To avoid this problem, the geometry of the teeth is modified. FE simulations are done for the existing model as well as for all the new models in order to find out which of them can handle the highest relative rotational speed. The results show that improvements can be done. Simple modifications of the teeth’s chamfer distance and chamfer angle shows that the dog clutch can handle up to 120 rpm of relative rotational speed whereas the original model only handles 50 rpm. Acknowledgements The thesis is performed at Linnæus University and SwePart Transmission AB during the spring semester 2010. We would like to thank the following persons: - Andreas Linderholt, (Linnæus University, School of Engineering, Växjö) for supervision of the whole project and many important hints when it comes to the computer software - Hans Hansson, (SwePart Transmission AB, Liatorp) for introducing the problem and providing us with all necessary data - Johan Lundgren and Magnus Ragnarsson, (Linnæus University, Mechanical Department, Växjö) for cooperation and many important observations from the experimental tests Table of Contents 1. INTRODUCTION ........................................................................................................................................... 1 1.1 BACKGROUND ............................................................................................................................................. 1 1.2 PROBLEM DESCRIPTION ................................................................................................................................. 2 1.3 PURPOSE AND GOAL ..................................................................................................................................... 3 1.4 LIMITATIONS............................................................................................................................................... 3 2. THEORY ....................................................................................................................................................... 4 2.1 THE FINITE ELEMENT METHOD........................................................................................................................ 4 2.2 ABAQUS .................................................................................................................................................... 7 2.3 IMPLICIT AND EXPLICIT METHODS .................................................................................................................... 8 3. METHOD .................................................................................................................................................... 12 3.1 MODELLING IN SOLIDWORKS........................................................................................................................ 12 3.2 SIMPLIFYING THE PROBLEM .......................................................................................................................... 12 3.3 DEFINING THE MODEL ................................................................................................................................. 14 4. RESULTS ................................................................................................................................................... 18 4.1 EXISTING GEOMETRY .................................................................................................................................. 18 4.2 MODIFIED TEETH ....................................................................................................................................... 19 4.3 MODIFIED CHAMFERS ................................................................................................................................. 20 4.4 RESULTS SUMMARY .................................................................................................................................... 22 5. ANALYSIS .................................................................................................................................................. 24 5.1 ANALYSIS OF EXISTING GEOMETRY ................................................................................................................. 24 5.2 ANALYSIS OF MODIFIED TEETH ...................................................................................................................... 25 5.3 ANALYSIS OF MODIFIED CHAMFERS ................................................................................................................ 26 6. CONCLUSIONS .......................................................................................................................................... 27 7. REFERENCES ............................................................................................................................................ 28 8. APPENDICES ............................................................................................................................................. 29 1. Introduction 1.1 Background This thesis is carried out on behalf of SwePart Transmission AB in Liatorp. SwePart designs and manufactures precision grinded gears and customer specific gearboxes as well as other transmission parts for vehicles and industry. SwePart Transmission AB shall by means of high competence and cost efficiency remain a leading supplier of transmission products. The main idea for this thesis is to investigate how improvements can be made to the transfer case in trucks with all-wheel-drive. The transfer case is located between the gearbox and rear wheel axels as shown in Figure 1.1. It is responsible for distributing power from the rear wheel drive shaft to the front wheels, and by doing so it creates all-wheel-drive. Transfer case Figure 1.1. Drive train for trucks with all-wheel-drive Normally a truck is driven by the rear wheels; when this is the case the front wheel driveshaft rotates freely in the transfer case. When all-wheel-drive is engaged power is delivered through the transfer case via three