A theoretical study analyzing three-dimensional combustion acoustic instabilities in a liquid propellant rocket engine combustor has been conducted. A linear theory based on Crocco’s pressure sensitive time lag model is used. To apply this theory the combustor is divided into two main components, including the combustion chamber and the converging part of the nozzle. The assumption of concentra...

in the current study, an effort is made to determine three dimensional bearing capacity of rectangular foundations using discrete element method. the soil mass is modeled as discrete blocks connected with winkler springs. different factors affect the geometry of failure surface. six independent angles are used to define the failure surface. by trial and error, the optimum shape of failure surfa...

A semi-analytical solution is presented for three dimensional elastic analysis of finitelylong, simply supported, orthotropic, laminated cylindrical panels with piezoelectric layers subjected to outer pressure and electrostatic excitation. Both the direct and inverse piezoelectric effects are investigated. The solution is obtained through reducing the highly coupled partial differential equatio...

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this paper deals with three-dimensional evaluation of the slopes on the basis of limit analysis. an upper-bound technique of limit analysis is used in this paper to determine either the bearing capacity of a shallow foundation near a slope or the safety factor of the slope. the theorems of limit analysis (upper and lower bound) provide a powerful tool for solving problems in which limit loads n...