Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Bursa Uludağ University, FEN BİLİMLERİ ENSTİTÜSÜ, Mechanical Engineering, Turkey
Approval Date: 2018
Thesis Language: Turkish
Student: TOLGA ÇAKMAK
Supervisor: Muhsin Kılıç
Abstract:In this study, improvement of the performance characteristics of dry clutch systems in heavy duty vehicles under thermal and mechanical conditions is investigated. As an application, 430 mm diameter product used in high tonnage truck and bus vehicles was evaluated. In the study, vehicle tests for repeated successive stop and take offs on the slope road and simulations of these tests were analyzed. For the thermo mechanical properties improvement of the dry clutch, pressure plate that has the most thermal absorption capacity, has been focused and the effect of improvements made on this component on the system performance has been evaluated. In this study, one of the points examined originally is the determination of the convection heat transfer coefficient between clutch casting pressure plate surface and air as a function of rotational speed and geometrical properties on the basis of experimental data. Thus, having estimation during design phase was targeted. Another original section is the presentation of energy dissipation and slippage duration results for the vehicle test that includes many repetitive take offs on a slope road. Temperature rise of the clutch housing air during the vehicle tests was simulated with 1D system, 3D finite element and computational fluid dynamics analyses. Simulations enabled to estimate the friction surface temperature and the number of cycles that clutch system could withstand. The main theme of the thesis; thermo-mechanical improvement has been evaluated within two aspects; design and material. In the design, the positive effect on the convection heat transfer by the ventilation channels, which had not been applied to the clutch pressure plate previously, was investigated. In the material, the improvement in conductive heat transfer was demonstrated by the change in chemical composition. The mechanical and thermal performance of the 28% lightweight prototype has been compared with the existing product. The cooling rate of the parts, the thermal crack resistance on the friction surface after consecutive engagements, and the mechanical burst performance at high rotational speeds have been investigated with the bench tests.