The main goal of this research is the experimental and numerical study of the fatigue function and failure of the crankshaft of the diesel engine of a heavy truck. To this end, a crankshaft of the diesel engine of a heavy truck that underwent failure after traveling 955000 km was used. The crack developed from the third crankpin, leading to nal failure in the llet of the 4th crankpin. To investigate the roots of this failure, several experimental studies were carried out. Besides, by using a three-dimensional nite element method, the location of the maximum stress in the crankshaft was determined using \complete crankshaft model" and \one-crank model". The application of the results of stress analysis was the basis for the crack growth model and fatigue life estimation to determine the stress intensity factor and fatigue life considering the related parameters and boundary conditions. At the nal stage, by using the results obtained from the given model for the fatigue crack growth, comparing them with experimental results, and examining the whole process, it was concluded that the scratches in crankpin region were the main reason for the fatigue failure obtained from the bending-torsional load-combination.

Regarding the growing need for cheap and unlimited energy sources, renewable energies have been considered. Solar energy is one of the main sources of energy. This article studies the performance of floating solar chimney technology for the manufacturing purpose in Isfahan city. In this purpose, Isfahan city is considered to determine the performance of floating solar chimney power plant (SCPP) to build this type of SCPP. The results have shown that the floating solar chimney power plant can produce 5-200 MW of electrical energy in Isfahan city. Then a study is performed according to return of finance rate, net price value, and finance return period criteria. The results have shown that these power plants are able to be built in large scales of 100 and 200 MW of electricity with an annual capacity of 381 and 712 GW with 44 and 60%, respectively. However, a comparison between the cost analyses of two tested models shows that the 200 MW power plant with a cost of 13,941.52 milliard Rials is more beneficial in Isfahan city.

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In this paper, a new micromechanical disc resonator with two L-shaped horizontal support beams in torsional mode vibrations has been proposed. The proposed micromechanical resonator has been studied in the field of natural frequencies and support loss. In order to verify the findings of natural frequencies, the analytical results are compared to the simulation results given by ANSYS software. A good agreement between analytical and simulation results is shown. In addition a closed-form equation for support loss quality factor in torsional mode vibrations of the proposed micromechanical resonator is presented. The results show that using L-shaped support beams can improve the support loss quality factor up to two times.