The effect of adherent thickness on the fatigue performance, fatigue limit, and failure mode of adhesively bonded thin aluminum single lap joint (SLJ) was experimentally and numerically investigated. High‐cycle fatigue tests were performed, and fatigue life was estimated using various fatigue criteria and finite element modeling. Based on the experimental results, increase in adherent thickness leads to increase in fatigue limit. In addition, failure location changes from adhesive to adherent by increasing the adherent thickness. It seems that in adherent failure, selecting a sheet with higher fatigue strength is required to achieve higher fatigue life. Also, based on the analysis of different fatigue criteria, Smith‐Watson‐Topper criterion could predict the joint fatigue life more accurately by considering the mean stress effect and the plastic strain. Finally, as an important result, an unsymmetrical SLJ specimen was evaluated as an industrial case study, and the empirical estimated life was consistent with the experimental results.
Collide of two objects or impact, is one of the main damage initiation reasons. In this paper, impact and damage behavior of elastic and visco-elastic bodies are investigated numerically using the finite element analyses. The results showed that visco-elastic materials, distribute stresses to the edge of model after the impact with a solid body. Furthermore, the impact of elastic and visco-elastic composite materials are analyzed and the variations of stress, displacement, damage energy and the damage patterns during a time period are compared for the two material models. The reduction in the values of stress, displacement and damage energy of visco-elastic material is also determined relative to the elastic composite material.
This paper presents a general integrated procedure of fabricating a Hybrid Electric Motorcycle (HEM). Firstly, a simple model designed and simulated using ADVISOR2002 and the proposed model is exported to MATLAB/SIMULINK. Secondly, the controller schematic and its optimized control strategy are described. In addition, the ratings of the components including the batteries, electric motor, and internal combustion engine (ICE) are calculated based on the design. A 125 cc ICE motorcycle is selected for conversion to HEM. A brushless DC (BLDC) motor assembled in front wheel as accessory propellant. The nominal powers are 8.2 kW at 8500 rpm and 500 W for the ICE and BLDC respectively. The original motorcycle has a Continues Variable Transmission (CVT) that is the best choice for the HEM power transmission because it can operate in automatic handling mode and has high efficiency. Moreover, by using CVT the ICE can be started while it is running at 15 km/h. Finally, the three operating modes of the HEM, the servo motors, and the LCD panel were explained.
In this paper, the first and second stage compressor blades of a gas turbine were studied by the experimental and numerical modal analyses. At first, the geometric models of these blades were generated by the 3D scanner and then the mode shapes and the natural frequencies of each blade were extracted by a series of numerical modal analyses. The numerical results were compared with the data obtained from the experimental modal analysis and the validity and accuracy of the developed numerical models were confirmed. Unlike most studies that use fixed-free boundary condition for performing a modal analysis, this objective was pursued by applying a free-free boundary condition. This study also investigated the effect of using wax or glue for mounting the accelerometer on the blade by assessing the FRF curves obtained from the modal tests in the frequency range of 0-10000 Hz. The sensitivity of the test results to applying free-free boundary condition, the number of accelerometers and their positions were investigated by defining three modal test configurations. The results obtained by these test configurations were compared with the results of numerical analyses and finally, the best configuration for the modal test of the studied compressor blade was determined.
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