نشریه مهندسی مکانیک و ارتعاشات
سال هفتم شماره 4 (پیاپی 25، زمستان 1395)

In this paper, the effect of using Sio2 nano-fluid on cutting tool temperature, during the hard turning of AISI 4340 hardened steel has been studied using both experimental and finite element methods; To achieve this goal, first a finite element model has been developed in case of dry hard turning of AISI 4340 hardened steel. The results of this model was then verified by experimental measurements of cutting forces and cutting tool temperatures. In continuation, a set of experimental tests were designed and executed to study the effect of nano-fluid application and its concentration on cutting tool temperature. According to the achieved results, there is a good agreement between finite element and experimental results. These results also show that, cutting tool temperature for hard turning of AISI 4340 is 30% of the dry hard turning and the percent of reduction in cutting tool temperature grows gradually with increasing nanofluids concentration (0.6 % wt)

Reducing energy consumption is the main purpose of design. Naturally, energy loss in each system can compromise the future of a system. This has drawn attention of researchers all around the world. Contentious structures the same as an engineering structure such as beam, plate, and shell are widely used in various industries. Much of industrial systems include these structures. However, the most important point in designing such structures is to avoid failure, reduce maintenance cost, and increase life of the structure. These points directly and indirectly can describe energy consumption and necessarily cannot meet the objectives of the design and not reach an optimal output and product. Vibration of any continuous system can have poor consequences on performance and can weaken the design of a system. Therefore, the effort to reduce vibration and control the mechanical phenomenon has a significant impact on reduced energy waste of a continuous structure (kinematic energy- potential energy). This paper sought to report scientific and research activities from 1980 to 2013 on vibration suppression of continuous systems focusing on optimal placement approach on the structure and installing piezoelectric S/A and smart model built by control approaches in order to attenuate and control unwanted vibrations of the system against external stimulations and disturbance.

Nowadays, in order to heating water in low-temperature residential applications, flat plate solar water heater is widely used. In this paper, we aim to discuss the thermal performance of MWCNT-water nanofluid in a flat plate solar water heater. The nanofluid has been prepared in solid volume fraction of 0.05% and its thermal performance has been experimentally investigated. In order to make a dispersed and stable nanofluid, Sodium Dodecyl Benzene Sulfonate surfactant has been used. The results showed that using the nanofluid has a considerable effect on improvement of the performance of the flat plate solar water heater. Furthermore, the increase of the system’s performance under natural circulation is much higher than that of forced circulation.

Inverse problem for spring-mass systems called shear structures is presented in this paper. Shear structure is a system with spring and mass after each other and there is a spring between two masses. Damping effects are neglected here. The aim is determining the mass and stiffness of the system with pre assigned frequencies. There is a method for solving such a problem that is presented here. Some examples are discussed. Such a problem can be used for several important problems.

Glasses are important topic in automotive manufacturing industry. Always automotive glasses because of safety and beauty are attracted attention by big automobile manufacturing companies and with development of the automotive industry, significant progress has been occurred in the glass industry. Today different types of glasses are used with various applications based on the needs. The different requests in the automotive industry, glass artisans have tried to turn into producing variety glasses. For example the first automotive front glasses were common glasses which because of rapid breakage during the accident and its dangers for passengers, unbreakable glasses have been produced to prevent passengers from smashed glass injuries. After that has been thought to produce PVB glass for raising the passenger safety, improving the quality and increase refractive index of glass. Laminated glass almost has been used in front glass of car for more safety and strength and also tempered glass has been use in order to behind and back glass.

Today with significant increase in production of polymeric products and advances in polymer science and technology, the importance of efficient management of polymeric waste has gain an even more significance. From efficient and practical solutions proposed in this field, recycling these wastes in order to produce gaseous and liquid fuels can be named as a valid and feasible solution. In addition to protecting the environment, this solution is a good replacement for natural fuels. Therefore, this research aims to increase the fuel efficiency and quality of plastic waste products via catalytic pyrolysis process. In this research, an expanded mathematical model is presented, and by using two methods of response surface and genetic algorithm, the proposed model and its parameters (reactor’s temperature and catalyst weight), for finding the optimal conditions shall be investigated. According to evaluation of base variance algorithm, the scale of deviation based on the expanded model, for liquid and gaseous fuel efficiencies is calculated to be 0.9641 and 0.9655 respectively.

The wings of projectile is one of the important components for correct controlling and navigation. In this study, in order to consider the vibration behavior of the wing, the governing equations of the opening process of the wing system until collision was derived using analytical method. Also, numerical method using ADAMS software and experimental set up are adopted to compare and verify the analytical analysis. This collision lead to an unwanted excitation of the wing which cause to it vibrates. For decreasing the amplitude of vibration of the wing in better manner, in this research a dynamic absorber is designed and made of Teflon as a damper. The dynamic behavior of the wing with the absorber is studied using analytical and numerical methods and the effect of many parameters such as friction coefficient, material properties of the wing pin and contact area is investigated to optimize its behavior. Obtained results demonstrate that increase in the friction coefficient decrease the returning angle and oscillation amplitude of the wing.