Sharif Digital Repository

This study presents delamination in fiber-reinforced composite laminates by using multiscale modeling. The meso modeling is used to derive the relationship between microcrack density and damage parameters. Next the selected failure model is applied to analyze the macroscale modeling. The progress of failure terms and the reduction of fiber and matrix properties implemented into ABAQUS/Standard, which enables an individual to create a new material behavior through the user subroutine UMAT. In the following, the contours associated with each of the damage parameters are obtained in each of the damage mode. Then for a specific material, the relationship between microcrack density and damage... 

In many cases, oil and gas extraction from reservoirs due to damage and permeability reduction near wellbore is lower than optimum level and reduces the flow of oil into the well. In fact, formation damage is the collapse of natural condition of reservoirs, In addition to delaying production and increasing costs, it causes early desertification of wells. Well stimulation methods are used to solve this problem and increase production. One of the most effective ways to increase the production of wells is well acidizing. In this study, the acid performance of the fractured carbonate reservoirs has been investigated. In this type of reservoirs, due to the existence of high permeable paths of the... 

The present thesis deals with the effect of matrix shear deformation on energy released due to debonding at fiber/matrix interface during fiber pull out test, which is modeled using two concentric cylinders representing fiber and matrix. Tensile on fiber causes a shear stress at the interface. When this stress exceeds the tensile strength of the interface, debonding occurs at the interface and grows as a crack along the interface. This debonding causes a relative axial displacement between fiber and matrix along the debonded interface, which varies along the debond crack. How fiber/matrix relative displacement changes along the debond region is not known. Thus, the fiber/matrix interface is... 

The daily development of societies and the advancement of various industries have led civil engineering to save on and use of environmentally friendly materials. Urban development and population concentration In some areas, Encourages engineers To use materials with more efficiency to design High-rise structures that have more lifetime or maintain them using modern methods. Concrete in most structures has a significant percentage of consumable materials, but it has limited tensile strength and flexibility. Fiber can be used to control the growth of cracks, prolonging useful life, controlling permeability and corrosion. Different types of fibers are used in concrete.In this study, we have... 

The daily development of societies and the advancement of various industries have led civil engineering to save on and use of environmentally friendly materials. Urban development and population concentration In some areas, Encourages engineers To use materials with more efficiency to design High-rise structures that have more lifetime or maintain them using modern methods. Concrete in most structures has a significant percentage of consumable materials, but it has limited tensile strength and flexibility. Fiber can be used to control the growth of cracks, prolonging useful life, controlling permeability and corrosion. Different types of fibers are used in concrete. In this study, we have... 

Despite major environmental and economic benefits of cold recycled asphalt mixtures, many agencies have not yet made widespread use of this technology due to its so-called poor field performance and lack of accurate information on mechanical properties of cold recycled mixtures. Fiber is one the additives that is sometimes used to enhance asphalt mixture properties. Using fibers to improve the performance of cold recycled asphalt mixture has been studied by a few researchers with somehow contradictory results. In this research, the effects of adding four synthetic fibers (Polypropylene, A-glass, Para-Aramid, and Polyester) and two waste fibers (Waste Polyester and Waste Nylon) with different... 

This article investigates the production of a novel nerve regeneration scaffold by using biodegradable and biocompatible components. In this research, we have provided different methods like electrospinning and PE hydrogels to fabricate it. Electrospun fibers are made of PLLA and CS/Gel combinations. ZnO nanoparticles were used as the piezoelectric agent. Piezoelectricity plays an important part in the strcture of neurons giving them the ability to transfer electrical messages throughout the body. NPs were completely dispersed in the PLLA solution. ZnO particles could increase produced voltages as the concentration increases. PLLA is biodegradable and provide good mechanical properties....