فهرست مطالب مهدی سعادت فر

Due to the importance and significant contribution of the population of the country’s youth and the necessity of their use of their products in order to health and replace them with urgent food, effective factors on purchase of their seafood processing were made.The research conducted with independent random method on 314 young people aged 15-29 in Gorgan through questionnaire design and distribution. In order to frequency the demographic characteristics and one-way Anova to examine the significance of differences, then the Duncan test was used to compare the number of questions adjusted based on a Likert scale. Four factors including odor, taste, weight and color were studied in the selection of fish processing including eviscerated fish, fish fillets, fried fish fillets, fish nuggets, frozen shrimp and fried shrimp. The results showed that young people chose fried fish fillets and fried shrimp more than other products, and among the tested look the first priority. Therefore, marketing policies can be tailored to the interests of young people in order to improve health and increase fish consumption based on the results of the present research.

In this article, an analytical solution for the problem of time-dependent creep analysis of a functionally graded magneto-electro-elastic rotating disc is presented. The material properties are considered to be power function of radius through radial direction. Firstly, using the stress-strain relation and strain-displacement relation together with equilibrium equation and thermal equation in plane-stress condition, a differential equation containing creep strains is found. Then, eliminating creep strains, an analytical solution for the mentioned differential equation is obtained which is actually the response in time zero. Then, considering fixed temperature boundary conditions, creep strains are kept and creep stress rates are found by an analytical solution of the obtained differential equation. Lastly, the radial stress, hoop stress, radial displacement, electric potential and magnetic potential can be calculated using an iterative method in every desired time. In the numerical examples, the effects of creep evolution, temperature boundary conditions and speed of rotation are investigated comprehensively.

An analytical solution for the problem of time-dependent stress redistribution of a piezomagnetic rotating hollow cylinder subjected to an axisymmetric thermo-magneto-electro-mechanical loading is derived for the condition of plane strain. A differential equation containing creep strains is found using the constitutive equations, equilibrium equation and solving heat equation in plate strain. In the first step, eliminating creep strains in the differential equation, an analytical solution for the differential equation is obtained. Then, by adding creep strains and assuming constant thermal conditions, the creep stress rates and electric and magnetic potential are obtained using solving a differential equation. Lastly, the history of stresses, radial displacement, magnetic potential, and electric potential during the time can be obtained using an iterative method. In the numerical examples, the effects of time passing on the structure behavior and the effective parameters such as thermal boundary condition, angular velocity, and electromagnetic boundary condition were investigated comprehensively.

Piezoelectric materials, in different shapes such as rectangular plate, annular plate, circular plate and cylindrical shell, have increasing application in industries in order to create smart structures. In this article, experimental and numerical analysis of free vibration of a two-layered cylindrical panel with metal and piezoelectric layer in different boundary condition is carried out. First, a single PZT-4 layer is polarized in radial direction. Using the Piezoelectric layer and an Aluminum layer, a two-layered smart panel is prepared. Then, the first natural frequency of the hybrid panel with free boundary condition is measured experimentally in three different ways. The hybrid panel is simulated in a finite element software (Abaqus). Results show good agreement between different experimental methods, as well as, between finite element model and experimental results. The accuracy, limitations and merits of different experimental methods are discussed completely. The results show that the natural frequency can be achieved accurately by excitation of actuator layer. Finally, the influence of different boundary conditions as well as geometrical parameter such as radios, length and thickness of smart cylindrical panel are investigated using the finite element software.