Sharif Digital Repository

Wide applications of elastomeric (rubber-like) materials have led to significant interest of researchers to these materials. Elastomers as a great category of polymeric materials,posses specific properties such as large elastic deformations and energy absorption which make them suitable for aerospace and automotive applications as well as shock and vibration absorbers.In this thesis, an exponential strain energy function (SEF) has been proposed for elastomers which well reproduces the mechanical behavior of these materials and also the material parameters are related to the physical parameters of the material molecular network. This SEF has been concluded from a relation proposed for the... 

Today because of increasing use of fuel, environmental problems and problems due to heavy structures in different industries it is important to use structures with high specific strength. Using different materials in structures like polymers accompanying aluminum could be useful. Polymers are light, heat insulating and have a high corrosion resistance. Polypropylene is one of the useful polymers which can have high impact energy and strength via adding Elastomer and Talc powder, relatively. One of the common ways in joining metal to polymer uses adhesive. It has variety of benefits such as low distortion in joining, different materials joints and having joints with complex geometry. Welding... 

The current research was conducted to investigate the sealing behavior of single-string and dual-string completion Packer. In order to transfer the oil from reservoir located underground to the surface, the string of tubings is used which is called oil well completion string. A typical completion string not only consists of tubings but also the other facilities such as safety valve, traveling joint, sliding side door and Packer as well. Some reasons including: the cost of drilling and challenges in setting wellhead equipment at some geographical situations, producing more oil and gas lead to extraction oil form more than one zone in the oil well. In addition, taking into the account that,... 

In this thesis, the mechanical properties of collagen hydrogels were characterized using Finite Element method and the collagen content effect on the mechanical properties of hydrogels were investigated. Hydrogels samples with different collagen content were assessed which caused diverse mechanical behaviors. Due to the nonlinear behavior of hydrogels, using numerical methods and simulation softwars can be helpful to determine the mechanical properties of these material and save agreat deal of time. Finite Viscoelaticity theory was exploited for a UMAT Subroutine in Abaqus and an special Starin Energy Function was selected to extract the formulations. The agreement between simulation results... 

Vibration control is one of the most critical aspects of designing space structures, as it can significantly impact the performance and operational lifespan of satellites. The launch phase is the most sensitive and critical stage in the satellite mission lifecycle, as intense vibrations are generated and transmitted to the satellite during this phase. To mitigate the severity of these transmitted vibrations, vibration isolators are employed. The objective of this study is to design and model a vibration isolator to control the vibrations transmitted from the launcher to the satellite during launch. To achieve this, an extensive investigation into vibration isolators used in the space...