جستجوی مقالات مرتبط با کلیدواژه « رینگ » در نشریات گروه « مکانیک »

Rolling ring is one of the most important metal forming processes for fabricating rounded geometries with optimal mechanical properties in the environmental direction. The ability to fabrication of two-layer rings can be used in many industries. One of the properties of these rings is the lightweight with high strength or wear resistance along with high strength. In this research, we have tried to study the ring rolling process of the bonded two-layer ring and its effective parameters during the process using finite element analysis by ABAQUS software and experimental test. The rings are attached for process simulation and empirical testing. In the end, a ring of two-layer of pure Lead 99.99% and Tin 63% was formed. Based on the results obtained from this analysis and according to the dimensions and parameters considered for performing the process, the tension created in the bonded two-layer ring is between the values of 1.146×105-1.800×107Pa and it has a strain of 0-1.187. Its contours of strain and stress are represented to better understand the process. Considering the results obtained from the simulation of the process, an experimental study of the ring rolling process of the bonded two-layer ring was conducted. The method of this study was first designed by the modeling software to design the casting model and then by designing the test, the number of tests required for the experimental test was obtained and then the number of materials needed for the test was calculated. After testing, the mechanical and metallurgical properties of rolled double rolled rings were investigated.

This paper presents the study on natural frequency of reinforced multi-layered isotropic cylindrical shells with three rings under external pressures. The multi-layered cylindrical shell is formed by three layers of isotropic where the inner and outer layers are stainless steel and the middle layer is aluminum. The reinforced multi-layered shell equations with three rings and external pressures are established based on first order shear deformation theory (FSDT). The governing equations of motion were employed, using energy functional and by applying the Ritz method. The boundary conditions represented by end conditions of the multi-layered cylindrical shell are simply supported-simply supported (SS-SS), clamped-clamped (C-C) and free-free (F-F). This research was solved with computer programming using MAPLE package. The influence of external pressure, rings position and different boundary conditions on natural frequencies characteristics is studied. The results shows that reinforced rings and external pressures have effect on the natural frequency of multi-layered isotropic cylindrical shell and cause the natural frequency to increase. The results presented can be used as an important benchmark for researchers to validate their analytical methods.

This research presents the study on mechanical buckling of thick-walled cylindrical shell made of functionally graded materials with ring supported under uniform axial and lateral loads. The mechanical properties of shell are variable along the thickness direction. First the governing equations on the buckling of the FGM cylindrical shell supported with ring are established based on third-order shear deformation theory. Then the governing characteristic equations were employed, using energy method and by applying the Ritz technique. In the following with solving characteristic equations, the critical load buckling of the FGM thick-walled cylindrical shell supported with axial and lateral loads are calculated. The boundary conditions represented by end conditions of the FGM shell are the following: clamped-clamped and free-free. To verify the validity of the proposed analytical method the results of this research are compared with the results came from using the finite element software. Finally, the effects of the different parameters such as thickness variations, boundary conditions, loading conditions and geometrical parameters of shell and ring on the buckling behavior of FGM thick-walled cylindrical shell are investigated. The results showed that by increasing the FGM volume fraction power in the shell structure, the critical buckling load increases and the location of the ring support has the significant effect on the critical buckling load. The results presented can be used as an important benchmark for researchers to validate their numerical and analytical methods.

The free vibration of cylindrical composite shell with internal liquid is studied in this paper. The shell composed of several layers and stiffeners which are rings and stringers. The first order shear theory was used for shell and stiffeners. Stiffeners were used in equations as discrete elements. The Raily-Ritz method was used for solving the problem. This method is based on minimum potential energy principle. The potential and kinetic energy of shell and each stiffeners and kinetic energy of liquid are subsituted in the functional of energy. The section shape of each stiffener is rectangle. The liquid is ideal and sloshing was neglected. For caching the best and the biggest natural base frequencies, shell and stiffeners were optimized by genetic algorithm. With use of genetic algorithm the best fiber angles of each layer of composite were obtained to reach the maximum base frequency, also best ratio of height to width was obtained and in last the number of rings and stringers and theirs height to width ratio were obtained to reach the optimized stiffened shell with highest base frequency.

Fine-blanking is an effective and economical shearing process which offers a precise and clean cutting edge finish, eliminates unnecessary secondary operations and increases quality. Fine-blanking process utilizes triple-action tools: a punch, a stripper with an indented V-ring and a Counter punch (ejector) to generate a highly compressive stress state. The deformation is more violent and localized than that of any other metal forming operations. Therefore it is difficult to fully understand the mechanism of the process. This study investigates the effect of V-ring indenter, clearance of die, Force of holder and Counter punch, etc on state of stress, quality and accuracy of production. Some parameters have both positive and negative effect on quality of production and the life of the tool. Utilizing V-Ring indenter in Die will increase quality of production and life of the tool. Also Artificial Neural Networks was used to simulate Fine-Blanking process. It has been shown that booth of FEM and ANN is suitable for simulating and forecast of effect of the parameters on production.

In this paper a study on the vibration of thin cylindrical shells with ring supports and made of functionally graded materials (FGMs) composed of stainless steel and nickel is presented. The properties are graded in the thickness direction according to a volume fraction power-law distribution.The cylindrical shells with ring supports which are arbitrarily placed along the shell and impose zero lateral deflections. The study is carried out based on third order shear deformation shell theory (T.S.D.T). The analysis is carried out using Hamilton’s principle. The governing equations of motion of FGM cylindrical shells are derived based on shear deformation theory. Results are presented on the frequency characteristics, influence of ring support position and the influence of
clamed-clamped boundary conditions.

Electro Discharge Machining (EDM) is a very efficient machining process widely used in manufacturing components of complicated geometry. Based on its nature, i.e. material removal by electric discharge, the process induces thermal stresses that in turn result in generation of wide spread micro-cracks on the surface of the machined part. In this paper the influence of EDM characteristic parameters on the surface microstructure in CK45 alloy steel which is suitable for manufacturing of forging dies has been extensively investigated. An extensive experimental programme has been carried out to explore the role of various EDM parameters on the quality of the machined surface. The relation of EDM parameters has been evaluated quantitatively using the test results and regression analysis. Predicting the impact of EDM parameters on the surface quality as the outcome of this study provides means to appropriately decide on the adjustment of parameters to their optimum values and achieve the desired die surface quality at reasonable manufacturing time and cost.