Andres Peratta - Academia.edu (original) (raw)
Papers by Andres Peratta
Corrosion, 2016
Structures subject to corrosion damage are likely to develop stress concentrations on the damaged... more Structures subject to corrosion damage are likely to develop stress concentrations on the damaged surfaces, and these stress concentrations may lead to initiation of cracks and possible crack growth. If dissimilar materials are present, it is likely that areas will exist where anodic current flows from a structural surface into the electrolyte, so causing mass loss from the surface. The magnitude of the anodic current density is directly proportional to the rate of mass loss from the surface, and can be used to determine surface shape change. Such shape change generally results in indentations, which from a stress analysis point of view act as stress-raisers. Simulation to determine magnitude of the stress concentration can identify most likely sites for crack initiation. The possibility of crack growth, and the time taken for the growth, can be determined using fracture and crack growth simulation. This paper explores the combined use of galvanic simulation and fracture/crack growt...
The paper deals with the assessment of human exposure to extremely low frequency electric fields ... more The paper deals with the assessment of human exposure to extremely low frequency electric fields using sophisticated numerical tools.
The aim of this work is to develop and validate a computational model for simulating galvanic cor... more The aim of this work is to develop and validate a computational model for simulating galvanic corrosion in macroscopic samples for further application in typical case scenarios appearing in an aircraft environment. The case study involved in this paper consists of a co-planar bimetallic pair composed of Aluminium AA 2024 and carbon fibre reinforced polymer (CFRP) immersed in saline solution. The computational approach, based on the Boundary Element Method (BEM), aims at solving current density and electric potential in the electrolyte and active electrode surfaces. The obtained BEM based numerical simulation tool is validated with experimental measurements in a controlled environment. The modelling approach as well as the experimental methodology for characterising the material properties used as input in the simulation and for validating the results is described throughout this paper. The experimental measurements of potential at different points in the electrolyte and total curren...
The application of corrosion modeling to aircraft structural components can provide significant v... more The application of corrosion modeling to aircraft structural components can provide significant value with regard to reducing fleet maintenance and the life-cycle corrosion cost of an aircraft. A computational modeling framework (corrosion service life model) is being developed to support the prediction of corrosion damage in aircraft structures. This framework includes easy-to-use software tools to predict corrosion rates based on implementation of analytical curve crossing techniques, and more sophisticated approaches, based on the creation of computational models that represent the actual component geometry. The analytical curve crossing technique has been developed to support new requirements being considered in the revised MIL-STD-889. A key aspect of this revision is that galvanic current, created when joining materials, is an important consideration for galvanic compatibility decision making. The more involved computational modeling approach expands on this and provides capab...
The boundary element analysis of the human body exposed to extremely low frequency (ELF) electric... more The boundary element analysis of the human body exposed to extremely low frequency (ELF) electric fields is presented in this work. The human being is represented by a multidomain inhomogeneous body of revolution. The formulation of the problem is based on the quasi-static approximation and the related Laplace equation form of the continuity equation. This Laplace equation has been solved by the boundary element method (BEM). Solving the resulting Laplace equation for the electric scalar potential, the induced current density inside the human body is obtained. This quantity is the fundamental parameter in further analysis of possible biological effects of ELF exposures. An illustrated computational example of the human body exposed to the electric field generated by an overhead power line is also presented.
Journal of Communications Software and Systems, 2007
Aluminium Alloy Corrosion of Aircraft Structures, 2012
Mesh Reduction Methods, 2009
Boundary Elements and Other Mesh Reduction Methods XXX, 2008
WIT Transactions on Modelling and Simulation, 2010
Simulation of Electrochemical Processes III, 2009
Advanced Computational Methods and Experiments in Heat Transfer XI, 2010
Disposal of hazardous chemical waste in abandoned underground mines is believed to be an achievab... more Disposal of hazardous chemical waste in abandoned underground mines is believed to be an achievable, low risk and relatively cheap way of disposal of hazardous waste. The objective of the FP5 EC project Low Risk Disposal Technology (LowRiskDT) was to investigate the prerequisites for using this alternative, to outline suitable design and construction technology and to make a performance assessment with special respect to environmental safety and cost. Calculations were made of the isolating capacity of reference repositories in terms of the concentration of hazardous ion species appearing in the far-field groundwater. Relevant flow and dispersion models were applied to the reference cases representing different rock structures and flow path patterns. The release and migration of dissolved hazardous chemical species with special respect to groundwater protection are determined for the worst-case scenario. A numerical tool has been developed that can be used for analysis of transport ...
Thermal analysis of human expoure to base station antennas radiation is presented in this work. T... more Thermal analysis of human expoure to base station antennas radiation is presented in this work. The formulation is based on a simplified cylindrical representation of the human body. Knowing the internal electric field and related total absorbed power in the human body, a resulting thermal response of the body due to the exposure to high frequency (HF) radiation can be determined. The temperature rise in the body exposed to base stations antenna radiation is determined by solving the bio-heat transfer equation via both the dual reciprocity boundary element method (DR-BEM) and finite element method (FEM). The temperature rise in the body is found to be rather negligible.
Analytical modeling of the human body exposed to extremely low frequency electromagnetic radiatio... more Analytical modeling of the human body exposed to extremely low frequency electromagnetic radiation is presented in this article, which contribution is based on the comparison between different approximations. Cylindrical approximation is based on a theory of receiving antenna and presentation of the human body as a parasitic antenna exposed to an incident electric field. Through cylindrical approximation, the induced current inside the human body is calculated. This current is used for evaluating adverse health effects that electric field has on the human body. Different cases of exposure are considered, taking into account insulation between human body and the earth. Ellipsoidal approximation is used as a comparison to cylindrical. Finally, the comparison with the numerical model is made. Numerical model is based on Boundary Element Method (BEM) and the results obtained are shown to be in very good agreement.
This work is focused on the simulation of the type of ICCP system in which a grid of anode ribbon... more This work is focused on the simulation of the type of ICCP system in which a grid of anode ribbons and distribution bars, buried below the base of a tank, is supplied with power from a transformer rectifier unit. Current flows from the anode ribbons through the wet sand in which they are embedded, to the base of the tank, and then back to the TRU. The ICCP system is represented mathematically as a circuit including the TRU, distribution cables connecting it to a number of distribution bars, an array of anode ribbons welded to the distribution bars, and the return cable connecting the tank base to the return of the TRU. The electrical circuit equations are solved to determine current flow and electrical potential throughout the grid of anode ribbons and distribution bars. Current flow from the surfaces of the anode ribbons into the surrounding electrolyte, and from the electrolyte into the surface of the tank base, is described using polarization curves, which encapsulate the non-lin...
Prestressed Concrete Cylinder Pipe (PCCP) is a rigid pipe designed to take optimum advantage of t... more Prestressed Concrete Cylinder Pipe (PCCP) is a rigid pipe designed to take optimum advantage of the tensile strength of steel and of the compressive strength and corrosion inhibiting properties of concrete and is frequently used for water transmission. PCCP consists of a steel cylinder embedded in a concrete core, which is helically wrapped with high-strength, hard-drawn wire after curing. The wire is embedded in thick cement slurry and coated with a dense cement mortar. While the cement mortar and additional coatings usually protect the prestressing wires from corrosion, in certain circumstances chlorides can diffuse into the mortar and reach the wires. Therefore PCCP transmission pipelines can also be protected by CP systems to mitigate the risk of corrosion damage when chlorides are high in the soil. This paper describes a computer modeling study which was designed to determine the protection provided by a CP system, to evaluate different design options, and to optimize the desig...
Corrosion, 2016
Structures subject to corrosion damage are likely to develop stress concentrations on the damaged... more Structures subject to corrosion damage are likely to develop stress concentrations on the damaged surfaces, and these stress concentrations may lead to initiation of cracks and possible crack growth. If dissimilar materials are present, it is likely that areas will exist where anodic current flows from a structural surface into the electrolyte, so causing mass loss from the surface. The magnitude of the anodic current density is directly proportional to the rate of mass loss from the surface, and can be used to determine surface shape change. Such shape change generally results in indentations, which from a stress analysis point of view act as stress-raisers. Simulation to determine magnitude of the stress concentration can identify most likely sites for crack initiation. The possibility of crack growth, and the time taken for the growth, can be determined using fracture and crack growth simulation. This paper explores the combined use of galvanic simulation and fracture/crack growt...
The paper deals with the assessment of human exposure to extremely low frequency electric fields ... more The paper deals with the assessment of human exposure to extremely low frequency electric fields using sophisticated numerical tools.
The aim of this work is to develop and validate a computational model for simulating galvanic cor... more The aim of this work is to develop and validate a computational model for simulating galvanic corrosion in macroscopic samples for further application in typical case scenarios appearing in an aircraft environment. The case study involved in this paper consists of a co-planar bimetallic pair composed of Aluminium AA 2024 and carbon fibre reinforced polymer (CFRP) immersed in saline solution. The computational approach, based on the Boundary Element Method (BEM), aims at solving current density and electric potential in the electrolyte and active electrode surfaces. The obtained BEM based numerical simulation tool is validated with experimental measurements in a controlled environment. The modelling approach as well as the experimental methodology for characterising the material properties used as input in the simulation and for validating the results is described throughout this paper. The experimental measurements of potential at different points in the electrolyte and total curren...
The application of corrosion modeling to aircraft structural components can provide significant v... more The application of corrosion modeling to aircraft structural components can provide significant value with regard to reducing fleet maintenance and the life-cycle corrosion cost of an aircraft. A computational modeling framework (corrosion service life model) is being developed to support the prediction of corrosion damage in aircraft structures. This framework includes easy-to-use software tools to predict corrosion rates based on implementation of analytical curve crossing techniques, and more sophisticated approaches, based on the creation of computational models that represent the actual component geometry. The analytical curve crossing technique has been developed to support new requirements being considered in the revised MIL-STD-889. A key aspect of this revision is that galvanic current, created when joining materials, is an important consideration for galvanic compatibility decision making. The more involved computational modeling approach expands on this and provides capab...
The boundary element analysis of the human body exposed to extremely low frequency (ELF) electric... more The boundary element analysis of the human body exposed to extremely low frequency (ELF) electric fields is presented in this work. The human being is represented by a multidomain inhomogeneous body of revolution. The formulation of the problem is based on the quasi-static approximation and the related Laplace equation form of the continuity equation. This Laplace equation has been solved by the boundary element method (BEM). Solving the resulting Laplace equation for the electric scalar potential, the induced current density inside the human body is obtained. This quantity is the fundamental parameter in further analysis of possible biological effects of ELF exposures. An illustrated computational example of the human body exposed to the electric field generated by an overhead power line is also presented.
Journal of Communications Software and Systems, 2007
Aluminium Alloy Corrosion of Aircraft Structures, 2012
Mesh Reduction Methods, 2009
Boundary Elements and Other Mesh Reduction Methods XXX, 2008
WIT Transactions on Modelling and Simulation, 2010
Simulation of Electrochemical Processes III, 2009
Advanced Computational Methods and Experiments in Heat Transfer XI, 2010
Disposal of hazardous chemical waste in abandoned underground mines is believed to be an achievab... more Disposal of hazardous chemical waste in abandoned underground mines is believed to be an achievable, low risk and relatively cheap way of disposal of hazardous waste. The objective of the FP5 EC project Low Risk Disposal Technology (LowRiskDT) was to investigate the prerequisites for using this alternative, to outline suitable design and construction technology and to make a performance assessment with special respect to environmental safety and cost. Calculations were made of the isolating capacity of reference repositories in terms of the concentration of hazardous ion species appearing in the far-field groundwater. Relevant flow and dispersion models were applied to the reference cases representing different rock structures and flow path patterns. The release and migration of dissolved hazardous chemical species with special respect to groundwater protection are determined for the worst-case scenario. A numerical tool has been developed that can be used for analysis of transport ...
Thermal analysis of human expoure to base station antennas radiation is presented in this work. T... more Thermal analysis of human expoure to base station antennas radiation is presented in this work. The formulation is based on a simplified cylindrical representation of the human body. Knowing the internal electric field and related total absorbed power in the human body, a resulting thermal response of the body due to the exposure to high frequency (HF) radiation can be determined. The temperature rise in the body exposed to base stations antenna radiation is determined by solving the bio-heat transfer equation via both the dual reciprocity boundary element method (DR-BEM) and finite element method (FEM). The temperature rise in the body is found to be rather negligible.
Analytical modeling of the human body exposed to extremely low frequency electromagnetic radiatio... more Analytical modeling of the human body exposed to extremely low frequency electromagnetic radiation is presented in this article, which contribution is based on the comparison between different approximations. Cylindrical approximation is based on a theory of receiving antenna and presentation of the human body as a parasitic antenna exposed to an incident electric field. Through cylindrical approximation, the induced current inside the human body is calculated. This current is used for evaluating adverse health effects that electric field has on the human body. Different cases of exposure are considered, taking into account insulation between human body and the earth. Ellipsoidal approximation is used as a comparison to cylindrical. Finally, the comparison with the numerical model is made. Numerical model is based on Boundary Element Method (BEM) and the results obtained are shown to be in very good agreement.
This work is focused on the simulation of the type of ICCP system in which a grid of anode ribbon... more This work is focused on the simulation of the type of ICCP system in which a grid of anode ribbons and distribution bars, buried below the base of a tank, is supplied with power from a transformer rectifier unit. Current flows from the anode ribbons through the wet sand in which they are embedded, to the base of the tank, and then back to the TRU. The ICCP system is represented mathematically as a circuit including the TRU, distribution cables connecting it to a number of distribution bars, an array of anode ribbons welded to the distribution bars, and the return cable connecting the tank base to the return of the TRU. The electrical circuit equations are solved to determine current flow and electrical potential throughout the grid of anode ribbons and distribution bars. Current flow from the surfaces of the anode ribbons into the surrounding electrolyte, and from the electrolyte into the surface of the tank base, is described using polarization curves, which encapsulate the non-lin...
Prestressed Concrete Cylinder Pipe (PCCP) is a rigid pipe designed to take optimum advantage of t... more Prestressed Concrete Cylinder Pipe (PCCP) is a rigid pipe designed to take optimum advantage of the tensile strength of steel and of the compressive strength and corrosion inhibiting properties of concrete and is frequently used for water transmission. PCCP consists of a steel cylinder embedded in a concrete core, which is helically wrapped with high-strength, hard-drawn wire after curing. The wire is embedded in thick cement slurry and coated with a dense cement mortar. While the cement mortar and additional coatings usually protect the prestressing wires from corrosion, in certain circumstances chlorides can diffuse into the mortar and reach the wires. Therefore PCCP transmission pipelines can also be protected by CP systems to mitigate the risk of corrosion damage when chlorides are high in the soil. This paper describes a computer modeling study which was designed to determine the protection provided by a CP system, to evaluate different design options, and to optimize the desig...