Experimental and numerical modeling of uplift behavior of rectangular plates in cohesionless soil

Niroumand, Hamed,Kassim, Khairul Anuar Techno-Press 2014 Geomechanics & engineering Vol.6 No.4

Uplift response of rectangular anchor plates has been investigated in physical model tests and numerical simulation using Plaxis. The behavior of rectangular plates during uplift test was studied by experimental data and finite element analyses in cohesionless soil. Validation of the analysis model was also carried out with 200 mm and 300 mm diameter of rectangular plates in sand. Agreement between the uplift responses from the physical model tests and finite element modeling using PLAXIS 2D, based on 200 mm and 300 mm computed maximum displacements were excellent for rectangular anchor plates. Numerical analysis using rectangular anchor plates was conducted based on hardening soil model (HSM). The research has showed that the finite element results gives higher than the experimental findings in dense and loose packing of cohesionless soil.

Uplift response of circular plates as symmetrical anchor plates in loose sand

Niroumand, Hamed,Kassim, Khairul Anuar Techno-Press 2014 Geomechanics & engineering Vol.6 No.4

Uplift response of symmetrical circular anchor plates has been evaluated in physical model tests and numerical simulation using Plaxis. The behavior of circular anchor plates during uplift test was studied by experimental data and finite element analyses in loose sand. Validation of the analysis model was also carried out with 50 mm, 75 mm and 100 mm diameter of circular plates in loose sand. Agreement between the uplift responses from the physical model tests and finite element modeling using PLAXIS 2D, based on 100 mm computed maximum displacements was excellent for circular anchor plates. Numerical analysis using circular anchor plates was conducted based on hardening soil model (HSM). The research has showed that the finite element results gives higher than the experimental findings in the loose sand.

Application of mesh-free smoothed particle hydrodynamics (SPH) for study of soil behavior

Niroumand, Hamed,Mehrizi, Mohammad Emad Mahmoudi,Saaly, Maryam Techno-Press 2016 Geomechanics & engineering Vol.11 No.1

The finite element method (FEM), discrete element method (DEM), and Discontinuous deformation analysis (DDA) are among the standard numerical techniques applied in computational geo-mechanics. However, in some cases there no possibility for modelling by traditional finite analytical techniques or other mesh-based techniques. The solution presented in the current study as a completely Lagrangian and mesh-free technique is smoothed particle hydrodynamics (SPH). This method was basically applied for simulation of fluid flow by dividing the fluid into several particles. However, several researchers attempted to simulate soil-water interaction, landslides, and failure of soil by SPH method. In fact, this method is able to deal with behavior and interaction of different states of materials (liquid and solid) and multiphase soil models and their large deformations. Soil indicates different behaviors when interacting with water, structure, instrumentations, or different layers. Thus, study into these interactions using the mesh based grids has been facilitated by mesh-less SPH technique in this work. It has been revealed that the fast development, computational sophistication, and emerge of mesh-less particle modeling techniques offer solutions for problems which are not modeled by the traditional mesh-based techniques. Also it has been found that the smoothed particle hydrodynamic provides advanced techniques for simulation of soil materials as compared to the current traditional numerical methods. Besides, findings indicate that the advantages of applying this method are its high power, simplicity of concept, relative simplicity in combination of modern physics, and particularly its potential in study of large deformations and failures.

A review on uplift response of symmetrical anchor plates embedded in reinforced sand

Niroumand, Hamed,Kassim, Khairul Anuar Techno-Press 2013 Geomechanics & engineering Vol.5 No.3

The most soil anchor works have been concerned with the uplift problem on embedded in non-reinforced soils under pullout test. Symmetrical anchor plates are a foundation system that can be resisting tensile load with the support of around soil in which symmetrical anchor plate is embedded. Engineers and authors proved that the uplift response can be improved by grouping the symmetrical anchor plates, increasing the unit weight, embedment ratio and the size of symmetrical anchor plates. Innovation of geosynthetics in the field of geotechnical engineering as reinforcement materials found to be possible solution in symmetrical anchor plate responses. Unfortunately the importance of reinforcement in submergence has received very little attention by researchers. In this paper, provision of tensile reinforcement under embedded conditions has been studied through uplift experiments on symmetrical anchor plates by few researchers. From the test results it has been showed that the provision of geogrid reinforcement system enhances the uplift response substantially under uplift test although other results are such as increase the ultimate uplift response of symmetrical anchor plate embedded using geosynthetic and Grid Fixed Reinforced (GFR) and symmetrical anchor plate improvement is very dependent on geosynthetic layer length and increases significantly until the amount of beyond that further increase in the layer length does not show a significant contribution in the anchor response.

Square plates as symmetrical anchor plates under uplift test in loose sand

Niroumand, Hamed,Kassim, Khairul Anuar Techno-Press 2014 Geomechanics & engineering Vol.6 No.6

The uplift response of symmetrical square anchor plates has been evaluated in physical model tests and numerical simulations using Plaxis. The behavior of square anchor plates during uplift test was studied by experimental data and finite element analyses in loose sand. Validation of the analysis model was also carried out with 50 mm, 75 mm and 100 mm Length square plates in loose sand. Agreement between the uplift responses from the physical model tests and finite element modeling using PLAXIS 2D, based on 100 mm computed maximum displacements was excellent for square anchor plates. Numerical analysis using square anchor plates was conducted based on the hardening soil model (HSM). The research has shown that the finite element results are higher than the experimental findings in loose sand.

Design of A New Hot Tearing Test Apparatus and Modification of Its Operation

M. R. Nasresfahani,B. Niroumand 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.1

This study introduces a new apparatus for quantitative assessment of hot tearing tendency in casting alloys. In this method, molten metal is cast in a T-shaped mold cavity. Each arm of the T-shaped casting is hooked onto a rigid flask which restrains its free contraction during solidification. One of the hooks connects to a load cell which enables the real-time measurement of the contraction load during the solidification process as well as the load-time curve of each experiment. Temperature-time curves are also plotted using K-type thermocouples placed in the casting hot spot and connected to a data-acquisition system. Through the use of this set up, it is possible to estimate the solid fraction at which hot tearing occurs. Experiments were conducted with Al-9 %Si alloy to investigate the accuracy of the apparatus and modify its operation. The influence of the mold thermal gradient on the load-time curve and the hot tearing severity were investigated. Microscopic study of the observed hot tear regions was also performed to characterize the hot tearing characteristics.

Production of Al-Si-SiCp Cast Composites by Injection of Low-Energy Ball-Milled Al-SiCp Powder into the Melt

Mohsen Ghahremanian,Behzad Niroumand,Masoud Panjepour 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.1

Al-7wt%Si-10wt%SiCp composite with uniformly distributed reinforcement particles with the average size of about 3 microns was produced by a special compocasting method in which the reinforcement was injected into the melt in the form of particulate Al-SiCp composite powder instead of SiCp. The effects of the rein-forcement addition form, the solid fraction of primary alpha-aluminum particles at pouring, and stirring speed on the incorporation of reinforcement particles into the matrix were investigated. Injection of particulate Al-SiCp composite led to improved incorporation and dispersion and reduced size of SiCp. Casting from the semisolid state significantly improved the incorporation of SiCp into the matrix. The optimal solid fraction of primary alpha-aluminum particles to achieve a reasonable combination of reinforcement incorporation and fluidity of the composite slurry was recognized to be about 0.1. The incorporation of SiCp was improved by increasing the stirring speed up to 500 rpm and then gradually decreased.

Electroless Ni-P-CNT Composite Coating on Aluminum Powder

Benyamin Abbasipour,Sayed Mahmoud Monirvaghefi,Behzad Niroumand 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.6

Ni-P-CNT composite coatings were deposited on micro-sized aluminum particles using electroless plating technique and the effect of different process parameters on the microstructural characteristics of the produced composite coatings were investigated. The results showed that a uniform Ni-P-CNT composite coating could be successfully deposited on the aluminum particles provided the electroless processing parameters were adjusted carefully. The most favorable coating quality was achieved at bath temperature of 80 °C,bath pH of 5.5 and CNT concentration of 1.25 g/lit. While a higher CNT concentration resulted in increased CNT agglomeration and poor CNT distribution in the Ni-P matrix, a lower CNT concentration resulted in fewer incorporated CNTs. Higher bath temperatures intensified the hydrogen gas evolution during the process and resulted in poor uniformity and presence of porosity in the coating. Low bath pH resulted in poor CNT incorporation and distribution in the Ni-P matrix and clustering of a large part of CNTs out of the coating.