a .ghaznavi

The suspension system, one of the essential parts of any vehicle which has a significant role in vehicle steering, accelerating, and braking. One of the suspension system's main components is the trailing arm, which is exposed to frequent loadings and is made by welding method. Due to the use and nature of this piece, its fatigue analysis is crucial. Since this part is made by welding process, its fatigue analysis is much more complicated than other parts. In this paper, fatigue life of the trailing arm is investigated by using different numerical method. At first, safety factor of the component is calculated using dang van criteria. Dang van is one of the most famous and appropriated method for multi axial non proportional loads. However it is not a good criterion in order to calculate the damage of the weld line. So Volvo method that developed base on the weld process and properties is consider for fatigue analysis of the weld line. The obtained results improve the necessity of using this kind of method for welding process.  Finally, it could be concluded that for fatigue analysis of a welded component such as trailing arm, using both method are necessary. Considering two different criteria for a component and comparing the obtained results of the trailing arm under non proportional applied load is one of the achievement of this paper. Of course by using this method, the calculated fatigue life of the trailing arm is accurate. At the end, it should be noted that the both applied methods, Dang Van and Volvo, are completely verified by the available experimental result in the reliable references.

Due to the role of the frame, in addition to strength and fatigue analysis, the deformation of the frame is also very important. But unlike strength and fatigue analyzes, there is no specific criterion for analyzing the deformation of the main frame. Therefore, in this paper, in addition to providing a method for deriving specific criteria for evaluating the permissible deformation of the frame and the drivetrain, with the help of simultaneous simulation of the frame and the drivetrain, a solution for determining the displacements and evaluating them under loads is presented. The performance of the main frame has also been examined in terms of strength. Due to the numerical nature of the proposed way, before obtaining the results, the quality of the elements is studied from various aspects to ensure the accuracy of the results. Finally, studies have shown that the presented geometry has the necessary strength, and also has sufficient rigidity against the applied loads on the wind turbine So the drivetrain installed on it without any problems can perform its function. Finally, the main frame strength safety factor is 1.3, the deformation safety factor of yaw bearing is 1.7, and the deformation safety factor of high-speed coupling is 1.1 in both axial and radial directions. Also, the deformation analysis of the drivetrain and frame assembly shows a 15% reduction in the life of the first bearing and a 50% reduction in the life of the second bearing installed on the main shaft of the wind turbine

Clinical and radiographic diagnoses of dental root fractures have always been difficult and require high accuracy in dental care and treatment. The aim of this study was to compare the diagnostic accuracy of intraoral digital radiography (PSP) and CBCT in the detection of horizontal and vertical root fractures (HRF and VRF). For this experimental study, 60 human mandibular teeth (30 anterior and 30 posterior multi-rooted teeth) were selected. Thirty randomly-selected teeth were fractured horizontally while the next 30 randomly-selected teeth were fractured vertically by use of a hammer and then the pieces were glued back together and were placed in a sheep mandible. Radiographic images of all the teeth were taken using intraoral digital radiography (PSP) and CBCT methods. Afterwards, two oral and maxillofacial radiologists assessed the images separately. The data were subjected to diagnostic analytic tests. There were significant differences in specificity, sensitivity, positive predictive value and negative predictive value between digital intraoral radiography (PSP) and CBCT in the detection of HRF and VRF. Kappa value for inter-observer and intra-observer agreement in VRF equaled 73.3% for CBCT and 54.2% for PSP, while in HRF it equaled 63.3% for CBCT and 55.4% for PSP. CBCT method has higher specificity and sensitivity in the detection of HRF and VRF compared with intraoral digital radiography.