Sharif Digital Repository

All humanare subject to a physiligical phenomenon known as tremor, which introduces unintended, relatively high frequency movments into various limbs. This involuntary movment is main reason of human disability in doing of precision tasks. Precision surgery like eye surgery is among them that surgeons must have very ittle tremor to enable them to oprate on the small anatomy of the eye. In this reaearch by emphasizing on reduction of muscle fatigue in precision surgery, weight balancing mechanism designed and analyzed. Fatigue is most important cause of tremor, thus we expected tremor amplitude reduce by reduction of muscle fatigue. Purpose mechanism is passive mechanism that balances the... 

Typical Numerical Control Machines, mainly are made a mechanism with axes perpendicular to each other. Because of lower weight, the parallel mechanisms are focused by CNC manufacturers. the Hexaglide mechanism is popular in parallel mechanisms used in CNC.Today, software of Solid modelling, generate G-Codes but this Codes works for conventional Numerical Control machines. for use of this G-Code for Parallel Mechanism CNC, a new controller should be designed to convert the standard G-Code motion command for Hexaglide CNC.The End of this project, is design and manufacture a controller for Hexaglide CNC that convert conventional G-Code for that and initiate drivers.Finally, the controller is... 

In this study, an equivalent homogenous material model is proposed for Al6061-T6/Al2O3 metal matrix composite using the hierarchical multi-scale modeling, and the capability of this model in simulation of machining process of this composite is investigated. Molecular dynamic study of the Al/Al2O3 interface is used to obtain the effect of crystallographic orientations and terminations on the tensile and shear strengths at the interface. The Reaxff potential function is employed to estimate the traction-separation relations at Al/Al_2 O_3 interface at temperatures of 300, 400, and 500 K. Next, a cohesive zone model is used at the micro-scale to simulate the interface between the matrix and... 

This paper presents a surface generation model for sculptured surface productions using the ball end milling process. Dimensional measurement using a coordinate measuring machine (CMM) has been commonly adapted in advanced manufacturing environment to ensure that manufacturing products have high quality and reliability. To conduct dimensional inspection efficiency in a computer integrated manufacturing (CIM) environment, there is an urgent need to derive a sampling strategy which can be used to specify a set of measuring points that lead to accurate sampling while minimizing the sampling time and cost. Owing to the variations in characteristics of geometric feature and manufacturing process,... 

Nowadays, with a constant increase in life expectancy, joints pain and deficiencies have become a major problem and the use of prosthesis is increasing. One of the most important joint in human body is the hip joint which bear a major share of forces in daily activities. Hip joint is a cup-sphere joint with 3 degrees of freedom (DOF). Therefore, design and manufacturing of such prosthesis is very important. The objective of this thesis is to develop the know how for manufacturing of a standard hip prosthesis by hot forging of Ti6Al4V alloy. First a review of kinematics of bones and joints and forces on hip joint is presented, then the proper process for manufacturing of the hip prosthesis... 

Modal analysis is very important in determining the physical properties of structures and mechanisms. This field is divided into two general parts: Experimental Modal Analysis (EMA) and Operational Modal Analysis (OMA). In the operational modal analysis, there are more challenges for the analyst due to the lack of inputs to identify the system. Many of the mechanical structures can not be analyzed experimentally and under specific loadings, but should be identified under actual operating conditions and in situations where the inputs of the system are not measurable. For this purpose, a modal analysis method called "Random Sub-Space Identification" (SSI) is intoduced, which uses only output... 

In recent years, additive manufacturing has been widely used in prototyping and production of industrial-commercial pieces. Additive manufacturing or three-dimensional (3D) printing is able to easily produce any piece for initial prototyping, no matter how complex it is. The fused deposition modeling (FDM) is a type of additive manufacturing process that produces the piece with the mechanism of feeding the PLA filament, then the molten polymer extrusion and depositing the fluid layer by layer with a high viscosity. Since the thickness of the layers is directly proportional to the diameter of the nozzle and the diameter of the used nozzles cannot be in the micron range (lower than 100...