In this research, in order to investigate the effect of the piezoelectric patch which is used as a sensor or actuator in rotating flexible structures such as a helicopter blade, the free vibrations of the rotating rectangular sheet with and without the piezoelectric patch have been presented. First-order shear deformation theory is considered for plate displacement and piezoelectric field. Considering the effect of Coriolis acceleration, centrifugal acceleration and centrifugal in-plane forces, the equations of motion are derived from Hamilton's principle and the electromechanical couple equation is obtained from Maxwell's equation. For piezoelectric, two electrical conditions, open circuit and closed circuit, which are used in sensors and actuators, respectively, have been considered. The equations are discretized with the help of the Numerical Method of generalized differential squares and the matrices of inertia mass, eccentricity, Coriolis and stiffness matrix are obtained. Natural frequency values for beam and rotating plate have been compared in Abaqus software. Also, the values obtained from the Numerical solution in MATLAB have been verified with articles and ABAQUS, which have high accuracy. The effect of parameters such as hub radius, rotation speed, sheet thickness, aspect ratio, piezoelectric patch thickness and applied voltage on the natural frequency of the system has also been investigated.

In this paper, recommended spiral passive micromixer was designed and simulated. spiral design has the potential to create and strengthen the centrifugal force and the secondary flow. A series of simulations were carried out to evaluate the effects of channel width, channel depth, the gap between loops, and flowrate on the micromixer performance. These features impact the contact area of the two fluids and ultimately lead to an increment in the quality of the mixture. In this study, for the flow rate of 25 μl/min and molecular diffusion coefficient of 1×10-10 m2/s, mixing efficiency of more than 90% is achieved after 30 (approximately one-third of the total channel length). Finally, the optimized design fabricated using proposed 3D printing Method.

Plastic hinge properties play a crucial role in predicting the nonlinear response of structural elements. The plastic hinge region of reinforced concrete normal beams has been previously studied experimentally and analytically. The main objective of this research is to evaluate the behavior of the plastic hinge region of reinforced concrete deep beams and its comparison with normal beams through finite element simulation. To do so, ten beams contain six deep beams, and four normal beams, under concentrated and uniformly distributed loading, are investigated. Lengths in the plastic hinge region involving curvature localization, rebar yielding, and concrete crushing zones are studied. The results indicate that the curvature localization zone is not suitable for the prediction of plastic hinge length in reinforced concrete deep beams. Based on the results it can be stated that in simply supported normal beams the concrete crushing zone is focused on the middle span, but in simply supported deep beams by creating a compression strut between loading place and support, the concrete crushing zone spreads along the compression trajectory. The rebar yielding zone of simply supported beams increases as the loading type is changed from the concentrated load at the middle to the uniformly distributed load.

Mansuri oil field, which is located at the South-West of Iran, has sand production problem and primary analyses proved the existence of this phenomenon in this field. Generally, there are three Methods to evaluate the sand production state which are empirical, Numerical, mathematical, and physical. Considering the Numerical capability to analyze complex geometries under high stresses condition, FLAC3D, which is a three-dimensional explicit finite-difference program for engineering mechanics computation, was employed to analyze sand production in this field. First, the Numerical model was calibrated using designed physical model and then, producing intervals and their perforations were modeled by numeric software. Its results showed that not only end-perforation instability is not the sole dominant mechanism in sand production, but also the effect of adjacent perforations on each other is more important. In this respect, there is an optimum pressure that causes perforations failure and catastrophic sand production. Mansuri field analyses demonstrated that the downhole pressure at its wells is near predicted optimum pressure and producing intervals are going to catastrophically produce sand.

‎In this paper‎, ‎a Numerical Method for finding the Numerical solution of the Burgers-Fisher and Burgers' nonlinear equations is proposed‎. ‎These equations are very important in many physical problems such as fluid dynamics‎, ‎turbulence‎, ‎sound waves and etc‎. ‎We describe a meshless Method to solve the nonlinear Burgers’ equation as a stiff equation‎. ‎In the proposed Method‎, ‎we also use the exponential time differencing (ETD) Method‎. ‎In this Method‎, ‎the moving least squares (MLS) Method is used for the spatial part and the exponential time differencing(ETD) is used for the time part‎. ‎To solve these equations‎, ‎we use the meshless Method MLS to approximate the spatial derivatives‎, ‎and then use Method ETDRK4 to obtain approximate solutions‎. ‎In order to improve the possible instabilities of Method ETDRK4‎, ‎Approaches have been stated‎. ‎Method MLS provided good results for these equations due to its high flexibility and high accuracy and having a moving window‎, ‎and obtains the solution at the shock point without any false oscillations‎. ‎The Method is described in detail‎, ‎and a number of computational examples are presented‎. ‎The accuracy of the proposed Method is demonstrated by several test simulations‎.

The current induced by removing a gate separating two fluids of close densities is simulated using a developed Smoothed Particle Hydrodynamic (SPH) model. The simulation is performed for fluids with density ratios between 0.9 and 1.0. To develop the two-phase model, no significant changes are applied to the basic SPH formulations, regarding the low density difference between the two fluids. The classic SPH equations are used with a small change: the speed of sound and the reference density are changed in order to produce the same reference pressure for both phases.In addition, density re-initialization is applied for each phase separately. The resulted in viscid flow has characteristics very close to or the same as the experimental results. The flow depth and the flow front speed are two parameters selected to validate the simulations. The effects caused by the variations in the density differences to the phenomenon and effectiveness of the applied Method are evaluated by performing a series of simulations of different density ratios and resolutions.