Search

Due to their excellent mechanical, electrical and thermal properties and ease of production, metallic bipolar plates are a suitable replacement for graphite and composite plates. Stamping is one of the most applicable processes to produce theses plates from a manufacturing cost point of view. Due to its excellent corrosion resistance and low density, titanium rises as a potential option for the manufacturing of the bipolar plates. In this paper, the formability of titanium bipolar plates having a thickness of 0.1mm with a parallel flow field has been experimentally investigated. The formability of the sheet was evaluated at warm temperatures using different forming speed and lubricants. After the experimental implementation of the designed tests based on the Taguchi method, the fracture depth of the microchannel of stamped samples was extracted. The results showed that the most elongation of the sheet will be achieved at 100℃. Likewise, the forming speed and temperature are the most effective parameters on the forming depth, respectively. On the other hand, the effect of the lubricant is not tangible compared to the other mentioned parameters. The maximum forming depth equal to 0.494mm was obtained using an experiment with a forming temperature of 100℃, speed of 4.8mm/min, and lubrication with MoS2. [ABSTRACT FROM AUTHOR]

In this paper, a laminated composite plate that was subjected to bending fatigue load was modeled based on the strength degradation theory of the composites. Also, effects of the fiber directions in the layers and layer stacking on the fatigue life of the plate were studied. First, the governing equation of the laminate plate in bending was obtained by the Navier theory. Then, by solving the governing equation, the deflection and stresses in the plies of each layer were obtained. Finally, using the Brotman-Sahu strength degradation theory, reduction of strength and stiffness in each layer of the plate in each loading step was determined. The data obtained in each step were used to specify the data and material properties of the next solution step. This process was repeated until a fatigue failure in the fiber or matrix began in one or more layers. Using the sudden death theory and iteration of the solution process, the final fatigue life of symmetric laminates with various stacking and fiber direction was investigated. In the numerical results, the carbon/epoxy composite laminate with different layer stacking was studied. [ABSTRACT FROM AUTHOR]

Vibration analysis of the plate is an important topic in high-speed train body design. Because of the dynamic loads on plates which are used in the wagon body of the train, vibration analysis and determination of the amount of deflection and bending of the structure is important in wagon design. A plate which is used in the high-speed train is composite plate. Composite plates are considered because of many advantages relative to the other plates, such as low weight, high strength and cost-effective. In this paper, the nonlinear free vibration analysis of the used plate in the wagon body of high-speed trains has been presented. First, a three layers sandwich plate used for car body of high-speed trains has been transformed into a single layer equivalent orthotropic plate. Von-Karman theory and the Galerkin method have been employed to solving the equations of motion of the equivalent orthotropic plate. The nonlinear natural frequencies of the first four modes of the system have been determined using the numerical and variational iteration methods (VIM). Then the effect of different parameters on the value of nonlinear frequencies of the first four modes has been studied. The Difference lower than 0.1% is observed between the determined natural frequencies by VIM, with initial condition limited to zero, and natural frequencies determined by linear vibration. The results show that natural frequency is increased by increasing elasticity modulus of the face, the thickness of the core and the thickness of the face of the sandwich plate. In addition, because of nonlinearity of plate vibration equations, natural frequencies of composite plate are increased by increasing initial condition. [ABSTRACT FROM AUTHOR]