Sharif Digital Repository

This study is devoted to the analysis and design of a recently proposed steel-FRP deck system. A methodology is being proposed to analysis the elastic behavior of the proposed deck. In this method the deck is modeled as an equivalent orthotropic plate which is constrained by rotational springs along its edges. An analytical model of the proposed deck is derived by using Rayleigh-Ritz method where the primary Rayleigh-Ritz shape functions are generated from orthonormal polynomials by using Gram-Schmidt procedure. The results of the proposed methodology show good agreement with finite element analysis results. In order to test the applicability of the proposed deck as buildings flooring... 

Recently, to improve the dynamic behavior of Reinforced Concrete (RC) slabs under impact load, the methods of externally bonding Glass Fiber Reinforced Polymer (GFRP) sheets to slab and internally reinforcing concrete by steel fibers have been proposed. Nevertheless, it is required to investigate the comparison between these two methods on response of RC slabs under impact loads. In this study, the influence of volume fraction of steel fibers, the number of GFRP sheet layers (one or two) and the arrangement of GFRP sheets (covering the whole or parts of surface), are examined. Performance of fourteen mm concrete slabs including one plain slab, one steel RC slab, three steel RC slabs... 

This project has been carried out to investigate the feasibility of using thermoplastic materials in constructing large wind turbine blades made of composite materials. By proving the similarity of the mechanical behavior of blades made of thermoplastic and thermosetting composite materials, the possibility of using these materials with better recycling capabilities has been studied. By studying different thermosetting and thermoplastic resins and checking the Processing methods and mechanical properties of thermoplastic resins, the materials for blades have been selected. The suitable manufacturing method for producing large blades with dimensions above 30 meters is the vacuum-assisted... 

Recently, corrugated steel plate shear walls (CSPSWs) have been shown to be an efficient lateral force resisting system for building structures. Corrugated plates have higher out-of-plane stiffness and improved buckling stability in comparison with flat plates which result in improved hysteretic behavior. The application of CSPSWs in tall buildings requires a wide range of thicknesses for the infill plates. Yet, the available range of thicknesses of corrugated plates is limited because of the restrictions associated with the process of cold forming. One solution to this problem is to use two corrugated plates as an infill plate. In this research, the cyclic performance of double corrugated... 

The purpose of this research is to study the behavior of some kind of conventional and retrofitted Khorjini connections, such as stress and strain concentration and eventually strain-jumping phenomenon. Thus the software ABAQUS 2019 was used to fabricate the FEM models of the connections with experimental prototypes. In analytical studies, 21 specimens with different sizes of the connection components were analyzed. True stress-strain curves for steel and weld materials were used and damage initiation and revolution were considered in the weld material. Also cracking of the welds was considered by a micromechanical method. The main defects of the connection are severe initial stiffness... 

For the sake of decrease in energy and force of earthquake, seismic isolators are used. Regular seismic isolators are too heavy and damaged by chemical materials, therefore in this research a new approach is used that steel shim plates replaced by carbon and polyamide fibers. The aim of this research is to obtain the dynamic and mechanical properties of carbon and polyamide fiber reinforced isolators in comparison with steel reinforced isolators. In this approach, firstly some specimens have been designed and manufactured, then compresional and cyclic shear tests were carried out on them. All three type isolators are cylindrical and have identical diameter and height. The steel, carbon fiber... 

Thin film solar cells have low efficiency compared to crystalline silicon solar cells; however, they are low-cost and flexible. In manufacturing these solar cells, thin films are deposited at high temperatures (higher than 200℃) on a thick metal, plastic, or glass substrate using sputtering and plasma enhanced chemical vapor deposition (PECVD) methods. Since the thin films and substrate have different thermal expansion coefficients, cooling the system from deposition temperature to room temperature induces thermal residual stresses in both the films and substrate. In addition, these stresses, especially those induced in the amorphous silicon layer can change the carrier mobility and band gap... 

This research evaluates the effect of external corrosion geometry and bending moment on the burst pressure of pipes. In recent decades, the use of natural resources of offshore oil and gas has increased, as a result, the use of offshore pipelines for transferring products has grown dramatically. At the same time, numerous accidents and explosions in offshore pipelines and its economic and environmental consequences indicates the importance of ensuring safe operation. Pipeline Integrity Management has been developed to ensure safe and efficient operation of pipelines. Integrity management includes planning, inspection, evaluation and repair. This cycle is checked continuously. The importance... 

Geomechanics has an immense impact on petroleum engineering and applies to the most aspects of petroleum extraction, from exploration and drilling to production and even reservoir abandonment. Studying the mechanical behavior of rocks in hydrocarbon reservoirs and overburden layers will lead to better characterization of mechanical state of the environment. Therefore, a solid understanding of rock mechanical behavior can play a crucial role in reducing operational issues of oil and gas extraction in different phases and prevent extra cost and time consumption. To illustrate, studies of wellbore stability and integrity, casing burst and collapse, drilling optimization, sand production,... 

In this paper, a machine learning-based atomistic-continuum multi-scale scheme is introduced to model the materials' geometrically and materially nonlinear behavior. The kinematic and energetic consistency principles are employed to link the atomistic and continuum scales. In order to establish the kinematic consistency principle, the periodic boundary condition is implemented for the atomistic RVE. The Ni-based superalloy, including 0 to 3% porosity, is considered for the models. Several parameter analysis is done to distinguish the proper atomistic RVE to be used in multi-scale models. The data set, including the stress-strain samples, is generated through molecular dynamics analysis... 

Varus-valgus deformity is the improper alignment of lower extremities, which results in the increment of the local stress within the cartilage and the consequent alteration of the performance mechanism of the soft tissues around the knee joint. This accounts for changes within the movement pattern and thus further deformities, which, when continued, can lead to more serious damage in the form of osteoarthritis. The aforementioned cycle can be prevented through the conduction ofosteotomy; a surgical procedure in which the addition or removal of a bone wedge can correct the improper alignment. The correct design and conduction of osteotomy in terms of the location, angle, and size of the... 

Internal corrosion is one of the most common defects in pipelines. In recent decades, the use of offshore natural oil and gas resources has increased dramatically, followed by the use of offshore pipelines to transport products. At the same time, numerous accidents and explosions in offshore pipelines and their economic and environmental consequences underscore the importance of ensuring safe operation. Pipeline integrity management has been developed to ensure the safe and correct operation of pipelines. Integrity management starts with planning, then leads to inspection, then evaluation, and finally to corrective action, and this loop is repeated regularly. In this loop, the importance of... 

Understanding mechanical behavior of engineering materials plays an important role in prediction of material response and helps to analysis and design of engineering structures. In this thesis, behavior of polymer concrete (PC) with three different epoxy resin ratios, ordinary cement concrete (OCC), lightweight concrete (LWC), lime mortar soil (LMS), four various types of sandstone and granite was investigated under uniaxial and triaxial compression. In order to predict the mechanical behavior of aforementioned brittle materials, their behavior was simulated in terms of axial stress and volumetric strain versus axial strain. For computation of volumetric deformation and softening behavior,... 

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... 

Resolvers, due to their robust structure, are widely used in automation systems. Among the types of resolvers, the accuracy of the Wound Rotor (WR) resolver in the occurrence of common mechanical errors is higher than other types of resolvers. therefore, in this thesis, an AFWRR is studied to improve the performance. Increasing the number of poles in WR resolvers is a good solution for increasing the accuracy of these electromagnetic position sensors. However, high-speed WR resolvers due to employing fractional slot windings suffer from rich sub-harmonics in the induced voltages. A common solution for suppressing the undesirable sub-harmonics is using multi-layer winding with appropriate... 

Eye and vision are the most important tools and the perceptual sense of human. This important vital member is one of the most vulnerable organs of human body. For example in the United States 1.9 million eye surgery are being done yearly which include 9 thousand globe rupture and 30 thousand blindness due to impacts on the eye. Eye traumas could have occurred as mechanical, radiation, thermal, chemical, etc. among these, the damages related to the airbag impact which is subset of mechanical damages, take a significant percentage. Presenting a model of human eye in car airbag blunt impacts during accident could be effective for receiving helpful information from damage of the internal parts... 

Nowadays, Eye injuries caused by blunt impacts are considered among the major causes of blindness and vision problems; therefore, studying the existence of possible damages can be quite useful and effective. One of the quickest and most suitable methods in identifying damage parameters is finite-element modeling of the human eye. In this regard, in the current study, first a geometrical design was created by incorporating CT-Scan images of the eye into Mimics and later Solid works software. Afterwards, the most suitable mechanical properties for the constituents of the eye were extracted from the literature. The mechanical properties of vitreous and Sclera were obtained by experimental... 

Additive manufacturing enables fabricating lattice structures with tailored mechanical responses based on lattice materials. Full exploitation of such a possibility requires reliable and efficient mechanical analysis tools to be explored by topology optimization algorithms for designing the interior architecture of the structures to meet the desired mechanical behavior. However, detailed mechanical analysis of lattice-based structures using the conventional finite element approach is prohibitively expensive due to lattices’ complex and fine features that demand adopting very fine space discretization. As an alternative, equivalent models based on the homogenization principle have widely been... 

So far many systems have been proposed to withstand the lateral loads. For example in a concrete structure, the two concrete moment frame and moment frame with shear wall are commonly used.in the latter case, the shear walls are used to bear a large part of lateral forces.one of the disadvantages of this system is the high consumption of materials and lack of maneuver on their shape. The curved concrete shear wall is a new seismic system that, due to the curvature on the plan, will have the ability to provide the hardness, strength, and ductility required to withstand lateral loads. The goal of this project is to investigate the seismic performance of these types of walls against cyclic... 

This study presents an experimental and numerical investigation on the compressive behavior of a new type of composite column which consists of both solid and hollow concrete-filled UPVC tube with and without GFRP wraps.Composite construction has been often more economical than traditional concrete construction, because this system realizes the most effective use of concrete, and composite members in the structural system.The enormous potential of using plastic tubes in composite systems will be illustrated by this research. It is an economical type of column in construction.This research aims to study the behavior of UPVC-confined columns under axial compression. A sum of 132 specimens are...