Stewart Platform Mechanism (SPM) is a type of parallel mechanism (PM) which has 6 degrees of freedom. Due to features like precise positioning and high load carrying capacity, PMs have been used in many areas in recent years. But relatively small workspace of the mechanism is the major disadvantage. This paper aims to improve the method for PM workspace analysis. The structure of Artificial Neural Network (ANN) which was used to analyze 6x3 SPM's workspace, is determined by Genetic Algorithms (GA). This structure of ANNs, i.e., weights, biases are very effective on catching highly accurate results of the ANNs. Therefore, calculation of these values and appropriate structure, i.e., number of neurons in hidden layers, by trial and error approach, results in spending too much time. To prevent the loss time and to determine the problem most fitted structure of hidden layers, a GA is developed and tested in simulation environment, i.e., software developed data. It is noted that by using software-calculated-parameters instead of using trial-error-approach parameters gives the user as accurate as trial-error-approach in short time span.

The present work investigates the mechanically forced vibration of the hydro-elasto-piezoelectric system consisting of a two-layer plate "elastic+PZT", a compressible viscous fluid, and a rigid wall. It is assumed that the PZT (piezoelectric) layer of the plate is in contact with the fluid and time-harmonic linear forces act on the free surface of the elastic-metallic layer. This study is valuable because it considers for the first time the mechanical vibration of the metal+piezoelectric bilayer plate in contact with a fluid. It is also the first time that the influence of the volumetric concentration of the constituents on the vibration of the hydro-elasto-piezoelectric system is studied. Another value of the present work is the use of the exact equations and relations of elasto-electrodynamics for elastic and piezoelectric materials to describe the motion of the plate layers within the framework of the piecewise homogeneous body model and the use of the linearized Navier-Stokes equations to describe the flow of the compressible viscous fluid. The plane-strain state in the plate and the plane flow in the fluid take place. For the solution of the corresponding boundary-value problem, the Fourier transform is used with respect to the spatial coordinate on the axis along the laying direction of the plate. The analytical expressions of the Fourier transform of all the sought values of each component of the system are determined. The origins of the searched values are determined numerically, after which numerical results on the stress on the fluid and plate interface planes are presented and discussed. These results are obtained for the case where PZT-2 is chosen as the piezoelectric material, steel and aluminum as the elastic metal materials, and Glycerin as the fluid. Analysis of these results allows conclusions to be drawn about the character of the problem parameters on the frequency response of the interfacial stress. In particular, it was found that after a certain value of the vibration frequency, the presence of the metal layer in the two-layer plate led to an increase in the absolute values of the above interfacial stress.