Kompozit Malzemeli Bir Şaftın Otomotiv Uygulamaları İçin Üretimi Ve Testi

Abstract

KOMPOZİT MALZEMELİ BİR ŞAFTIN OTOMOTİV UYGULAMALARI İÇİN ÜRETİMİ VE TESTİ

Automotive driveshafts are generally manufactured from steel or aluminum material and constructed in multiple pieces to avoid bending resonance. Composite materials have emerged as an alternative solution for torque tube material recently, enabling reduction to a single piece due to higher values of axial moduli. In this thesis; design, manufacture and testing of a composite driveshaft is sought, which is to replace a 2-piece metallic driveshaft on a heavy weight commercial vehicle. Carbon/Epoxy composite torque tube of the driveshaft is to be produced by filament winding, regarding fundamentals of the method are also presented. Torque tube is modelled by utilizing Classical Laminate theory in analytical domain; numerical model was developed with finite element method. Material properties obtained from the literature is used for the initial evaluation of models. Manufacturing of composite materials is a complex issue and material properties depend on many parameters. The properties of actual material may differ from catalogue values found in the literature. To address that issue, test plate production is carried out in accordance with ISO 1268. Specimens are cut from test plates and mechanical properties are determined by testing per regarding ASTM standards. End connections constitute, perhaps the most interesting and challenging issue about producing a composite driveshaft. In this particular design, end connections, which are machined from blocks of C50 material, are planned to be co-cured with filament wound carbon/epoxy shaft tube. An adhesive layer of epoxy would develop between them and its strength is investigated in order to transmit the design torque safely. In order to ensure safer transmission, hexagonal shape for the joint is chosen to provide coupling between the shaft and joint. An appropriate amount of taper is given to provide a smooth inner bore and continuous layers. Manufacturing setup consists of the mandrel body and end connections mounted on it. Masking tape is applied to cylindrical surfaces in order to preserve them and release agent is applied on all surfaces bar the connection geometry. Carbon fibers, which are impregnated with epoxy resin system, would be wound on this setup. After curing cycle, the mandrel would be removed thus leaving a composite cylinder adhered to the end connections, which is our composite driveshaft in either test rig or vehicle configuration. Some problems had been encountered on conic hexagonal connection geometry during trial windings so draping analyses of connection geometries were carried out. Conic hexagonal connection geometry has been replaced with a polygonal section. Static and fatigue testing of the prototype shafts are planned. A torsion test rig is designed to be employed on the MTS322.21 universal testing system for transforming the axial force of the system into a torque loading by the utilization of a torque arm. A prototype driveshaft has been manufactured but rig tests are yet to commence. 28 kilograms of weight saving is achieved which constitutes to 35% of the structure. Design requirements are fulfilled, except for the natural frequency which might be attributed to the lower moduli of the production material. Better planning of the filament winding process would yield a production material with better properties resulting in further weight savings and a higher natural frequency for a production shaft.