Developments in vehicle technology reveal that increased demands on vehicle comfort and fuel efficiency in the vehicles require to design more efficient powertrain systems. Vibrations originated in the engine need to be well optimized and controlled at desired limits. For this purpose, modal analysis for vehicle components is the main analysis method to evaluate the vibration behaviours. During vehicle design, important parameters for vehicle vibration such as inertia and stiffness are investigated and modified values to be replaced to get lower vibration values by means of the modal analysis. In this study, the truck powertrain system is modelled with real system values by the 1-D analysis software program and modal analysis is performed to find mode shapes and vibration magnitudes of the powertrain system components. Mode shapes of the clutch damper was investigated by changing damper stiffness values and the other components variables were taken constant to evaluate the stiffness effects on the system by modal analysis.

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Tractors are one of the most important agricultural machinery in the world. They provide agricultural activities in challenging conditions by using various agricultural machineries which are added on them. Therefore, there has been a rising demand for tractor use for agricultural activities. During the power transmission, tractor clutches are exposed to high static and cyclic loading directly. Thus, most of clutch parts fail before completing their design life which is under 106 cycles. Especially, because of the high stress, there are a number of fractures and breakages are observed around the pin area of the finger mechanisms. Due to these reasons, it is necessary to re-design these fingers by using modern optimization techniques and finite element analysis. This paper presents an approach for analysis and re-designs process of tractor clutch PTO finger. Firstly, the original designs of the PTO fingers are analyzed by using finite element analysis. Static structural analyses are applied on these fingers by using ANSYS static structural module. The boundary conditions are determined according to the data from the axial fatigue test bench. Afterwards, the stress-life based fatigue analyses are performed with respect to Goodman criterion. It is seem that the original design of the PTO finger, failed before the design life. Hence, the PTO finger is completely re-designed by using topology and shape optimization methods. Topology optimization is used to find the optimum material distribution of the PTO fingers. Topology optimization is performed in solidThinking Inspire software. The precise dimensions of the PTO fingers are determined by using shape optimization and response surface methodology. Two different design parameters, which are finger thickness and height, are selected for design of experiment and 15 various cases are analyzed. By using DOE method three different equations are obtained which are maximum stresses, mass, and displacement depending on the selected design parameters. These equations are used in the optimization as objective and constraint equations in MATLAB. The results indicate that the proposed models predict the responses adequately within the limits of the parameters being used. The final dimensions of the fingers are determined after shape optimization. The new designs of the PTO fingers are re-analyzed in terms of static and fatigue analysis. The new design of the PTO finger passed the analysis successfully. As a result of the study, the finger mass is increased 7% but it is quite small. Maximum Equivalent Von-Misses stress reduction of 25.3% is achieved. Fatigue durability of the PTO finger is improved 53.2%. The rigidity is improved up to 27.9% compared to the initial design. The optimal results show that the developed method can be used to design a durable, low manufacturing cost and lightweight clutch parts.

-The objective of this study is to investigate thermal durability of grey cast iron GJL250 material flywheel based on casting graphite flake size under abusive and unusual driving condition which causes forced slippage. In daily routine, drivers may make half press of clutch pedal and switch the gear out of sequence during long traffic condition. This case leads to slippage between flywheel and clutch that causes energy dissipation in clutch house. During slippage, thermal load on flywheel increases and when it reaches critical level this may cause thermal cracks on flywheel. In this study, graphite flake size effects on thermal durability were investigated. In order to simulate daily abusive usage, flywheels which have different graphite flake type and size were subjected to forced slippage test at the test bench which simulates the abusive usage on the car. The findings of this study is different size of graphite flake types on flywheel directly effects the thermal performance of material and may cause prominent cracks during over dissipated energy occurrence. At the end of the forced slippage test, the cast iron which has higher graphite size completed the test without crack, whereas prominent cracks were observed on the casting which has smaller laminar graphite size.

Automobile components are subjected to high dynamic loads and vibrations under operational conditions which needs detailed system analysis for work properly. The torque generated in the engine creates oscillations, and this case occurred at different levels of frequencies. Clutch is one of the important part of automobile powertrain system with torque transmission controlling and vibration damping properties. Metallic helical springs are widely preferred within the clutch discs with their durable mechanic properties against dynamic variables on an automobile. This study develops the novel approach on the time-based investigation of rubber clutch springs, and system optimization for torsional vibration damping using the simulated annealing algorithm method. In this purpose, the torque behavior of the rubber spring instead of the helical spring was investigated by experimentally in time-dependent manner. Rubbers consist of polymer chains which are highly sensitive to dynamic variables such as operation time, frequency and thermal load. The clutch disc which includes rubber damper spring made of NBR (Nitril rubber) is experimentally tested with functional torque measurement at different compression cycle times to observe rubber damper spring viscoelastic time-based behavior. As the next step, 1-D modeling of powertrain system, including rubber clutch damper springs, were subjected to vibration optimization with simulated annealing (SA) algorithm. Thus, the simulated annealing (SA) algorithm was developed, and integrated run is provided with 1-D modeling for optimization in Python script. This methodology accelerates the powertrain system optimization using both rubber and metallic damper types with eliminating many of real vehicle testing and saving cost and time before the production phase. Also, results give an idea on the importance of 1-D simulation before design modeling of rubber clutch damper system based on time-dependent conditions.