Dental implants restorations basically include four parts: implant, abutment, metal framework, and crown. In this common kind of restoration, crown is cemented to metal framework. However, in this research a novel method of design of dental implant is presented which includes only two components: Integrated implant, and Crown. The new designed is based on an integrated implant which enables dentist to fit the crown by a snap-fit ring instantly. In order to carry out stress analysis, the finite element method (FEM) is applied on implant and bones to verify different loading conditions. The results of FEM are presented and proved to satisfy different loading conditions successfully. تفاصيل المقالة

In this paper, multi-stage optimum design of composite pressure vessels is presented. The design variables for composite vessels include the head shape, the winding angle, the layer thickness, the number of layers, and the stacking sequence. A parameter called modified shape factor is introduced as an objective function. This parameter takes into account the effects of the internal pressure and volume, the vessel weight, and the composite material properties. The proposed algorithm uses genetic algorithm and finite element analysis to optimize the design parameters. As a few examples, this procedure is implemented on geodesic and ellipsoidal heads. The results show that for the given vessel conditions, the geodesic head shape with helical winding angle of nine degrees has the better performance. تفاصيل المقالة

Automobile body plays crucial role in preventing the collision energy transfer in severe accidents to the passengers. If the collision energy is dissipated or saved in bumper or chassis, the amount of damage to the occupants would be minimized. Using novel laminated panel (Fiber Metal Laminate) in auto body, and considering the characteristics such as high energy absorption, strength, high dent resistance, and very light weight, has caused significant reduction in injury to the car passengers. One of the major plans in auto industry is to lessen emission and fuel consumption using light weight material in auto body, which is recently achievable by replacing multi light layers with single metal layer panels, in auto body. These panels are usually made of two thin metal layers surrounding the core composite. The first point regarding panels is their strength against depression which is so called Dent Resistance. Weight reduction of panels should not sacrifice dent resistance of panels. The purpose of this paper is to investigate fiber metal laminate panels, dent resistance analysis and the amount of energy absorption of these panels, in order to implement in auto body. Strength, high dent resistance, and very light weight of such panels may lead into substantial reduction in crash injuries during car accidents. تفاصيل المقالة

An interface part is used between clutch pedal and clutch cable in Peugeot, Samand, RD and Peugeot pars. This part is consisted of two pieces. The Main body is made of polyamide 6.6 and the second part is made of CK45.Due to the fact that the two pieces are made of different assembling geometry with respect to each other, therefore, has caused performance problems which may result in clutch cable failure. Thus, a new interface part is designed in such a way that has a better assembling geometry and has overcome the previous problems and improved part functionality. تفاصيل المقالة

Successful development, evaluation, and qualification of propulsion systems such as turbojet and turbofan engines and rocket motors require the measurement of the performance and reliability of these systems. Thrust stands or testers are instruments for solid and liquid motors test. These apparatuses extract the characteristics of motors such as temperature, pressure, force and torque. In this paper, the dynamic design principles of a typical thrust stand have been detailed and methods to improve dynamic response have been developed. A thrust stand should be affected by random vibrations of solid motors as slightly as possible during firing. At first some Power Spectral Density (PSD) of three kinds of solid motors has been calculated by MATLAB codes. Then a number of tester structures by Solidworks have been designed and their dynamic responses have been determined by ANSYS codes. An attempt has been made to improve dynamic responses through changing the structure. Results showed that just some models could be improved. Increase of natural frequencies protects the structure from motors random vibrations. Truss structure is a good choice for testers. Decrease of mass, using different types of tube sections and short members are effective methods for improving dynamic responses. تفاصيل المقالة

Abstract: The lifetime of a cutting tool is an important and determinant parameter for evaluating its performance. The amount of tool abrasion affects seriously dimensions and surface quality of the working piece so that one of the main factors to determine the lifetime of a tool is the level of its wearing. For this purpose, an abrasion standard is defined for each particular tool above which the tool is not applicable any more. In the current paper, studies are concentrated on the machining of PH-hardened Austenitic-ferritic (Duplex) stainless steel (330HRC) to analyze the effect of tool wear on the lifetime of the ceramic cutting tool with Alumina base (aluminum oxide). Abrasion tool parameters like Flank wear, Crater wear, and Notch wear have been considered. To develop the mathematical models for the parameters considered in tool wear, the experimental results are applied in multi regression analysis (MRA) and the results obtained by these models are considered and analyzed by the analysis of variance (ANOVA). تفاصيل المقالة

In designing the landing gear of an airplane, one of the most important factors to consider, is the effect of landing airplane on body, and the role of shock absorber as an energy absorber resulting from landing. In this thesis, the landing gear of airplane has been analyzed using two approaches namely theoretical and simulation software. First, dynamic equations of landing airplane were investigated in six degrees of freedom and then, these equations were converted into space state and consequently solved using MATLAB software. In second approach, the airplane was modeled in ADAMS and different states of landing such as landing with two wheels, landing with three wheels, passing over a bump and taxi were compared and analyzed. Finally, using the above approaches velocity and displacement of airplane mass center were investigated, discussed and compared. تفاصيل المقالة

Stereolithography process limits wider applications due to low dimensional accuracy comparing with CNC. To improve accuracy and reduce part distortion, understanding the physics involved in the relationship between the setup input parameters and the part dimensional accuracy is prerequisite. In this paper, a model is proposed to find and optimize important parameters to achieve a high accuracy and also, to prediction dimensional accuracy with various values of parameters. For this purpose, the result of a previous study is used. It is found in Stereolithography these factors, respectively, have a most impact on dimensional accuracy in parts built SLA: layer thickness, hatch style, hatch spacing, hatch fill cure depth and hatch overcure. The proposed neural network model in this paper is able to predict dimensional accuracy with about 6 percents error. تفاصيل المقالة