Mechanic of Advanced and Smart Materials

Abstract In general, every normal cell of the human body, which consists of different parts such as the nucleus, cell membrane and protein nanofibers, has a certain mechanical hardness and strength. Any noticeable change in this strength indicates a disease. One way to diagnose various diseases such as cancer in normal cells of the human body is to measure the amount of changes that have occurred in their mechanical properties. In the present paper, mechanical properties including modulus of elasticity and adhesion force of Ago-1522 cell, which is considered as a natural skin cell, using JPK atomic force microscope (made in Germany), Nano Wizard 3 in both extension and retraction modes, and obtained at a temperature of 37 degrees Celsius. Based on the results, the average elastic modulus for the cell in the extension mode (as the valid mode in the reports) is equal to 574.4 Pa. The adhesion force is equivalent to N in retraction mode. Based on images taken from the surface of the cell with an atomic force microscope, its maximum height is 0.4 micrometers.

Abstract In this paper, the hydromagnetic propulsion system in marine application is taken into account. If the conduction fluid channel is exposed to a magnetic field and an electric field perpendicular to the fluid flow, under the interaction of electric current and magnetic field, a force is generated to flow the fluid, which is the basis of hydromagnetic propulsion systems. Hydromagnetic propulsion systems have a variety of applications which the most important ones are molten metal transfer system, small hydromagnetic pumps and marine propulsion system. Therefore, in this research, a literature review is performed and 70 valid scientific references in this field are studied and presented. Various classifications of the hydromagnetic thrust system are presented based on the installation location, type of electric field, type of fluid conducting channel, etc. The operating applications of hydromagnetic thrust systems are presented for all types of marine and submarine cargos. This paper can be a benchmark for future researches on hydromagnetic propulsion systems.

Abstract The purpose of this study is to investigate the method of mechanical alloying and its effect on the compounds obtained from the Ti-Si- ternary powder system. According to studies, it has been observed that the mechanical alloying method alone cannot produce pure Ti3SiC2 compound; Therefore, ancillary processes such as annealing heat treatment and plasma spark ignition process have been used. To conduct the research, a powder mixture of Ti, Si, and C with stoichiometric ratio according to the chemical composition of Ti3SiC2, was milled in 3: 1: 2 by an energetic ball milling with balls (with different radious) to powder weight ratio of 20: 1 and a speed of 360 rpm from zero to 20 hours. To evaluate the thermal stability of the formed phases after 20 hours of milling and to determine the mechanism of formation of Ti3SiC2, the 20 h milled sample was subjected to DTA thermal analysis. Then, to clarify the peaks obtained during DTA analysis, the 20 hours milled sample was thermally treated at 1200 ° C and 1400 ° C a for 1 hour under argon atmosphere. X-ray diffraction pattern was used to identify the phases at different milling times and also to identify products obtained from thermal analysis at temperatures of 1200° C and 1400 ° C. The results showed that the increase of the milling time not only increase the purity of Ti3SiC2 but also causes impurities mainly carbide phases, TiC and SiC.

Abstract In this paper, using the Sobol sensitivity analysis method, which is based on variance, 11 factors affecting the optimization of the loading path of the hydroforming process are investigated, then the feasibility and validation of the results with other optimization methods such as finite element and experimental method are reported. Is Input factors include, expansion pressure, final pressure, yield time, end of expansion time, intermediate mandrel displacement, final mandrel displacement, intermediate mandrel displacement time, initial position of reciprocating mandrel, final position of reciprocating mandrel, start time of reciprocating mandrel and time The stops of the reciprocating mandrels are considered, then the effect of each of them on the minimum thickness and maximum height in the loading path of the hydroforming process to produce T-joints is investigated and reported in detail. Quantitatively and qualitatively, the optimal values are obtained for each of the 11 input factors and are calculated based on the loading paths.

Abstract The widespread use of lightweight and flexible structures in industries such as aerospace and the increasing use of thin plates in these structures, which are easily fluttered and unstable in rapid air currents, make the use of active and inactive control methods to control the flutter inevitable. In the present study, by examining the governing equations and employing SOF (Static Output Feedback) method, we have tried to position the vibration sensors to get the closest performance to the LQR controller. To do this, a rectangular plate exposed to supersonic current is considered. A piezoelectric patch is used to control the vibrations. A rectangular plate exposed to supersonic current is considered. A piezoelectric patch is used to control the vibrations. Von Karman thin plate theory and Mindlin moderately thick plate theory are used for simulating the plate. The first-order piston theory is used to model the airflow. The equations of motion are obtained using the Lagrange method and the displacement field approximation by finite power series. Then, a criterion for finding the points whose displacement feedback combination can provide the closest control performance to the LQR controller is presented. Finally, the performance of the obtained criterion has been evaluated and confirmed by numerical simulation. The results show that the plate's flutter can be effectively suppressed at speeds beyond twice the critical velocity, feeding back a specific combination of certain points' displacements. The results show this method presents a performance comparable to the LQR controller, despite removing the state estimator.

Abstract In this article bending analysis of composite Euler-Bernoulli micro-beam made of functionally graded materials resting on elastic foundation by strain gradient theory has been studied. The material properties of structure have been assumed by Reddy’s power law model such as the bottom layer and top layer being ceramic and metal material respectively. At first, by using the assumptions of elasticity strain gradient theory and calculating the total potential energy of system after determining the work of external distributed load by using the Hamilton's principal the equations of motion have been derived. Note that the work down by the Winkler elastic foundation is considered. Because the solutions of mentioned equations are not possible by analytical method, the equations have been solved by generalized differential quadrature method in simply supported boundary conditions. By comparing the answers of problem with other published references, we confident form the obtained results. At the end, effect of material length scale and power law index coefficient of functionally graded materials and stiffness of elastic foundation on deflection of micro-beam has been studied.

Abstract The perturbation friction process is a solid state method used to modify the surface, improve mechanical properties, and produce composites. In this research, the effect of effective parameters on the surface compositing of AZ31B / CNT alloy with carbon nanotubes has been investigated by the frictional perturbation process method and Sobel sensitivity analysis. Input parameters in this study were advance speed, rotation speed, weight percentage of carbon nanotubes and number of welding passes, as well as considered outputs including hardness and weight loss. In order to analyze the results, Sobel sensitivity analysis has been used to investigate the qualitative and quantitative impact of inputs on outputs. The results of this study showed that the weight percentage of carbon nanotubes, rotation speed, number of welding passes and advancement speed affect hardness, respectively. The weight percentage of carbon nanotubes, the rotation speed, the number of welding passes and the advancing speed also affect the weight loss.