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Articles by S.S. Mohtasebi
Total Records ( 7 ) for S.S. Mohtasebi
  H.S. Hassani , A. Jafari , S.S. Mohtasebi and A.M. Setayesh
  Grain losses due to harvesting with combine harvester is one of the main obsession in direction of wastes and losses control. For this purpose reduction of losses due to cutting platform of combine which comprises more than 50% of the entire harvesting losses, is one of the main and principle measures in decreasing the combine losses. The JD 1165 combine harvester manufactured by ICM. Company is equipped with variable pulley and belt mechanism for ground speed, which causes lots of vibration and increases the losses and depreciation of the machine. In this study the amount of losses of JD 1165 harvester combine equipped with variable pulley and belt mechanism has tested and investigated. For this purpose a typical JD 1165 combine was selected and adjusted for various functional specifications. Then in Markazi province a field with flat land was chosen, in which 307020 Shahriar and Bekras varieties planted in water farm and in seven repetitions so that the moisture of grains ranged between 8 to 12% the research was carried out. As consequences demonstrated, grain losses induced from platform of the investigated combine gained 1.29% and losses at the back of the combine was 0.96% on average in seven repetitions. In addition, the most amount of damaged grains achieved 10.8% at the speed of 850 rpm for the cylinder. Finally, suggestions were made in order to improve performance of the machine.
  H.S. Hassani , A. Jafari , S. Rafiee , S.S. Mohtasebi and A.M. Setayesh
  The JD 955 combine harvester manufactured by ICM. Company has two hydraulic circuits which are the principal circuit (dividing valve circuit) and the steering circuit. Therefore, investigation and inspection of defects of the hydraulic system used in combine, considering its functions in the machine is so significant. In this article the problems of the hydraulic system throughout JD 955 combine harvester and the way services are given for disappearing the problems, have been investigated. For this purpose some 90 combines were selected which had been supplied to the customers over the last one or two years. The 140 defects detected from their hydraulic circuits were analyzed then services supplied to the selected combines and actually after sales services were researched within some categories. Results showed that the hydraulic pump had the most problems and was spent the most expense. In addition, throughout the after sales service categories only charges of the defects had significant difference with each other. Finally some policies suggested in order to decrease and eliminate the defects.
  S.S. Mohtasebi , A. Keyhani and M. Rahimi
  In this study, the fuel pressure regulator for MPFI PAYKAN 1600 cc engine which is a diaphragm operated valve has been simulated, analyzed and tested. The fuel pressure regulator is usually mounted on the fuel rail to maintain a constant relative pressure (3.5 bar) between the fuel injector and the air intake manifold. The regulator is first described and analyzed based on its functionality. Then, the mathematical equations of various sections of the regulator are presented. After that and based on those equations, the mathematical model of whole system is derived. This model is solved and analyzed using MATLAB engineering software. The good agreement between simulation and experiment results provided confidence to use the mathematical model to find out the steady state and transient responses of the regulator at different operating conditions. Finally, to make the regulator less sensitive to parameter variations, the sensitivity analysis is also done.
  S.S. Mohtasebi , H. Afshari and H. Mobli
  Due to the requirements of advanced industries to use lighter materials at high speed, static analysis of stress and strain can not be applied as a complete and powerful method, the dynamic behavior of the system should also be considered, however, the results should be confirmed by experiment. In this research, first, in order to investigate the effects of flywheel on natural frequency of crankshaft, the crankshaft, by using ANSYS software, was modeled in two cases; with flywheel and without flywheel at free-free condition. In the second phase, experimental modal analysis; the way that gives particularization of system responses, was applied to measure Frequency Response Function FRF). To do the experiments, the crankshaft was hanged in the laboratory and impact testing was applied to obtain FRF by a two channels FFT analyzer. Since the FRF is independent from input forces and actually it shows the inherent characteristics of the structure at the measuring points, FRF was measured just at drive points for each crankshaft. Finally, based on theoretical and experimental results, it is concluded that the cast-iron crankshaft is better to be used in NISSAN-2400 engines than steel crankshafts.
  M. Omid , S.S. Mohtasebi , S.A. Mireei and E. Mahmoodi
  In this study, a finite element routine was first used to calculate the static displacements and stresses under the maximum compression and tension loadings in the connecting rod of universal tractor (U650), which were then used for critical points evaluation. Fatigue analysis and longevity after a 1000000-cycle load, assessed through using of ANSYS software. Calculations based on fatigue life and accurate loading histories permit rod to be optimized for durability without the need for expensive and time-consuming testing of series of prototypes. According to this study, the critical point of the connecting rod of U650 is end of the shank and near piston pin hole (point 46). This point is critical point not only in tensional loading but also in compressive loading. The allowable number of cyclic loading on this part under fully reversed loading assumption is 108 cycles that will be increased by decreasing amount of the stress concentration coefficient. The results obtained from the present study can be used to bring about modifications in the process of connecting rod manufacturing.
  Z. Oveisi , S.S. Mohtasebi , V. Esfehanian and A. Keyhani
  Generally in this study, a closed-loop control algorithm is used to present suitable ignition timing at different engine operating conditions and neural network is used for estimating the peak pressure position of cylinder with only five points entries of cylinder pressure curve and then the optimum ignition timing of engine is obtained. After that, engine model in Boost software environment is used and peak pressure position of cylinder is obtained in optimum ignition timing and different speeds and loads of engine and is used for training neural network and so average value of that position is considered as the target value of controller. With comparison of several neural networks with different neuron numbers in hidden layer, optimum neural network model with structure 5-5-1 and 99.89% simulation accuracy is obtained. Net entries are five points of cylinder pressure curve and the number of hidden layer neurons is five. Also, a neuron in the output layer is used to find the peak pressure position of the cylinder. Since the control method is based on the cylinder pressure, all the equations related to the engine in this field were studied and a program for getting cylinder pressure based on crankshaft angle is written in Matlab engineering software environment. Finally, all of algorithm steps and written equations in Matlab were solved and results in engine speed of 2000 rpm with wide open throttle showed that the control algorithm can suitably keep the peak pressure position of the cylinder constant in 15.89° after top dead center while target value of the controller was 16°. Thus, the ignition timing is very close to MBT value which is equal to the peak pressure position of 16°.
  H.S. Hassani , A. Jafari , S.S. Mohtasebi and A.M. Setayesh
  Throughout the present research, the gears fatigue of the hydraulic pump for the principal circuit in JD 1165 harvester combine was investigated through the finite element method and using contact analysis for precise determination of the contact region of the engaged teeth so that their lifespan was estimated. For this purpose, first, the gears were modelled and with applying material specifications, contact and fatigue analysis were carried out sequentially utilising ANSYS software. The reason for performing this research was to study the intended gears behavior affected by fatigue phenomenon due to the cyclic loadings and to consider the results for more savings in time and costs, as two very significant parameters relevant to manufacturing. The results indicate that with fully reverse loading, one can estimate longevity of a gear as well as find the critical points that more possibly the crack growth initiate from. For the investigated gears, the most critical points were detected as nodes numbered 36573 and 37247. Furthermore, the allowable number of load cycles and using fully reverse loading was gained 0.9800E+07. It is suggested that the results obtained can be useful to bring about modifications in the process of the above-mentioned gears manufacturing.
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