Dr. Ahmad Barari is a graduate of The University of Western Ontario (PhD in Mechanical Engineering), Sharif University of Technology (MSc in Mechanical Engineering) and Amirkabir University of Technology (BSc in Mechanical Engineering/Manufacturing). He is currently an assistant professor at the University of Ontario Institute of Technology (UOIT). Since the mid 1990’s he has been primarily involved in research and teaching in engineering design and manufacturing. He has contributed to several industrial/academic projects in auto industries,CAD/CAM applications, coordinate metrology and inspection, machine tool calibration, rapid prototyping and additive manufacturing. Address: http://www.ahmadbarari.com/
There is a widely accepted consensus that component manufacturing precision is directly correlate... more There is a widely accepted consensus that component manufacturing precision is directly correlated with improved functional performance. However, this increase in precision comes at the expense of higher manufacturing costs, resulting in a trade-off between quality and affordability. In light of this opposing behavior, low-cost products typically exhibit lower quality, whereas high-quality products tend to be more expensive. This study introduces a novel approach for optimizing the dimensional tolerances of mechanical assembly components, taking into account both their manufacturing requirements and the associated costs of non-quality. Furthermore, the method considers the functional constraints imposed by interrelated tolerance chains within the product. Instead of relying on an exact mathematical solution, the proposed solution employs a heuristic approach through a simple and flexible algorithm. This enables practical implementation, as different cost-tolerance functions can be s...
Abstract Machining accuracy is affected by varying kinematic properties and singularities of para... more Abstract Machining accuracy is affected by varying kinematic properties and singularities of parallel mechanisms inside their workspace. In this research an asymmetrical four degree of freedom parallel kinematic machine tool with rotational capability around one of its horizontal axis, developed for milling processes is investigated for its machining capability. Surface roughness of Al5083 alloy is analysed after machining on various domains of available workspace. Linear interpolation was used in creating tool paths to avoid kinematic non linearity of parallel mechanisms and experiments are conducted using Response Surface Methodology (RSM) and gathered data is modelled by linear regression. Surface roughness results demonstrated the high machining performance of the mechanism inside available workspace.
Given its layer-based nature, additive manufacturing is known as a family of highly capable proce... more Given its layer-based nature, additive manufacturing is known as a family of highly capable processes for fabricating complex 3D geometries designed by means of evolutionary topology optimization. However, the required support structures for the overhanging features of these complex geometries can be concerningly wasteful. This article presents an approach for studying the manufacturability of the topology-optimized complex 3D parts required for additive manufacturing and finding the optimum corresponding build direction for the fabrication process. The developed methodology uses the density gradient of the design matrix created during the evolutionary topology optimization of the 3D domains to determine the optimal build orientation for additive manufacturing with the objective of minimizing the need for support structures. Highly satisfactory results are obtained by implementing the developed methodology in analytical and experimental studies, which demonstrate potential additive ...
Digital Twins are essential in establishing intelligent asset management for an asset or machine.... more Digital Twins are essential in establishing intelligent asset management for an asset or machine. They can be described as the bidirectional communication between a cyber representation and a physical asset. Predictive Maintenance is dependent on the existence of three data sets: Fault history, Maintenance/Repair History, and Machine Conditions. Current Digital Twin solutions can fail to simulate the behaviour of a faulty asset. These solutions also prove to be difficult to implement when an asset’s fault history is incomplete. This paper presents the novel methodology, LIVE Digital Twin, to develop Digital Twins with the focus of Predictive Maintenance. The four phases, Learn, Identify, Verify, and Extend are discussed. A case study analyzes the relationship of component stiffness and vibration in detecting the health of various components. The Learning phase is implemented to demonstrate the process of locating a preliminary sensor network and develop the faulty history of a Sand ...
On-line data collection from the manufactured parts is an essential element in Industry 4.0 to mo... more On-line data collection from the manufactured parts is an essential element in Industry 4.0 to monitor the production’s health, which required strong data analytics. The optical metrology-based inspection of highly reflective parts in a production line, such as parts with metallic surfaces, is a difficult challenge. As many on-line inspection paradigms require the use of optical sensors, this reflectivity can lead to large amounts of noise, rendering the scan inaccurate. This paper discusses a method for noise reduction and removal in datapoints resulting from scanning the reflective planar surfaces. Utilizing a global statistic-based iterative approach, noise is gradually removed from the dataset at increasing percentages. The change in the standard deviation of point-plane distances is examined, and an optimal amount of noisy data is removed to reduce uncertainty in representing the workpiece. The developed algorithm provides a fast and efficient method for noise reduction in opti...
This paper represents how typical advanced engineering design can be structured using a set of pa... more This paper represents how typical advanced engineering design can be structured using a set of parameters and objective functions corresponding to the nature of the problem. The set of parameters can be in different types, including integer, real, cyclic, combinatorial, interval, etc. Similarly, the objective function can be presented in various types including integer (discrete), float, and interval. The simulated annealing with crystallization heuristic can deal with all these combinations of parameters and objective functions when the crystallization heuristic presents a sensibility for real parameters. Herein, simulated annealing with the crystallization heuristic is enhanced by combining Bates and Gaussian distributions and by incorporating feedback strategies to emphasize exploration or refinement, or a combination of the two. The problems that are studied include solving an electrical impedance tomography problem with float parameters and a partially evaluated objective funct...
Anais do Congresso Brasileiro de Automática 2020, 2020
A análise de vídeos de futebol é uma área de recente interesse, particularmente a reconstrução 3D... more A análise de vídeos de futebol é uma área de recente interesse, particularmente a reconstrução 3D de partidas de futebol a partir de vídeos televisionados. São propostos três algoritmos que combinados suportarão esta reconstrução 3D de modo automático. Inicialmente, a região do jogo é determinada, que corresponde à região da imagem onde está a bola, o juiz e os jogadores. Posteriormente, as linhas do campo são determinadas utilizando a transformada de Hough, filtros de cor de geométricos são utilizados para remover falso-positivos. As intersecções entre as linhas determinam pontos invariantes que são mapeados a pontos do modelo do campo. O correto mapeamento permite corrigir a distorção perspectiva. Para determinar o mapeamento correto são realizadas combinações de correspondência entre os pontos invariantes e pontos no modelo do campo. O mapeamento do plano do gol também é determinado.
This paper presents the multiobjective optimization of the aerodynamic shape of an airfoil in vis... more This paper presents the multiobjective optimization of the aerodynamic shape of an airfoil in viscous and non-viscous flows by using the continuous adjoint optimization method. Different solvers have been developed to solve the flow and adjoint equations. The designed adjoint equations solver is capable of inverse designing the shape of the airfoil and the flap as well as optimizing their shape according to design parameters and constraints considered. The method of adjoint equations is a gradient-based method that requires the calculation of the design variables sensitivities in order to evaluate the optimal amounts for lift and drag coefficients. The main feature of this method is the ability to calculate sensitivities by solving the “adjoint equation”. In this research, the Navier-Stokes equations are discretized using continuous adjoint optimization, extracting the necessary equations for the adjoint optimization code. Resumo: Este artigo apresenta a otimização multiobjetivo da ...
Volume 1A: 35th Computers and Information in Engineering Conference, 2015
The final dimensional and geometric inaccuracies, and the resulting high surface roughness of the... more The final dimensional and geometric inaccuracies, and the resulting high surface roughness of the products have been the major problems in employing Additive Manufacturing (AM) technologies. Most of commonly used Additive manufacturing (AM) technologies are developed based on a layer-based manufacturing process to fabricate 3D models. The main critical issue in AM which reduces the surface integrity of the final products is the stair case error which happens due to layer by layer manufacturing process. A new method is presented to model the surface roughness of FDM parts based on considering a new geometry for the cusps. Variety of observations were conducted to model the exact geometry of the cusp. Considering that cusp geometry affects the surface roughness directly, the new geometry was used to predict the surface roughness distribution as a function of layer thickness and surface angle of the final FDM products. The model was validated by designing a set of experiments using 3D ...
Heavy vehicles service brakes are subject to severe loading conditions that can exceed the design... more Heavy vehicles service brakes are subject to severe loading conditions that can exceed the design conditions of safe operating performance in critical situations. Materials are prone to lose their design properties at high temperatures. Since the function of brakes is to convert the vehicle kinetic energy into heat by friction, temperature is the main variable to be considered, due to the fade of the linings composite material and cast iron drum deformation. The intent of this work is to evaluate the thermal loads of brake drums, when subjected to severe service conditions, in order to allow further analyses, mainly related to their dimensional and form variation. A case study is described, showing the possibility of the development of high temperatures and consequent risk of accidents in a real long downhill descent. Experimental data were preferably used to assure higher accuracy to the analysis. In the authors’ further work, a FEA simulation will be conducted with the data suppli...
This paper presents an experimental platform which is used to study the effect of DLC coating on ... more This paper presents an experimental platform which is used to study the effect of DLC coating on surface roughness. Variety of experiments is conducted and the effect of variation of the coating process parameters and type and combination of sub layers on the surface roughness of the coated part is discussed.
The traditional input to almost all commercially available Additive Manufacturing (AM) systems is... more The traditional input to almost all commercially available Additive Manufacturing (AM) systems is in STL (Standard Tessellation Language) format, which represents a solid model by its tessellated surfaces. This does not allow transferring the entire information of a solid model to the additive manufacturing preprocessing system. However, in some recent applications such as additive manufacturing preprocessing simulation, closed-loop of topology optimization and additive manufacturing process planning, and AM-based design optimization the full access to the solid model information is necessary. Slicing of the finite element model directly is introduced in this paper. The presented approach enables access to the entire solid model information during the AM preprocessing tasks with a focus on coupling the topology optimization in the design process with the actual manufacturing constraints.
There is a widely accepted consensus that component manufacturing precision is directly correlate... more There is a widely accepted consensus that component manufacturing precision is directly correlated with improved functional performance. However, this increase in precision comes at the expense of higher manufacturing costs, resulting in a trade-off between quality and affordability. In light of this opposing behavior, low-cost products typically exhibit lower quality, whereas high-quality products tend to be more expensive. This study introduces a novel approach for optimizing the dimensional tolerances of mechanical assembly components, taking into account both their manufacturing requirements and the associated costs of non-quality. Furthermore, the method considers the functional constraints imposed by interrelated tolerance chains within the product. Instead of relying on an exact mathematical solution, the proposed solution employs a heuristic approach through a simple and flexible algorithm. This enables practical implementation, as different cost-tolerance functions can be s...
Abstract Machining accuracy is affected by varying kinematic properties and singularities of para... more Abstract Machining accuracy is affected by varying kinematic properties and singularities of parallel mechanisms inside their workspace. In this research an asymmetrical four degree of freedom parallel kinematic machine tool with rotational capability around one of its horizontal axis, developed for milling processes is investigated for its machining capability. Surface roughness of Al5083 alloy is analysed after machining on various domains of available workspace. Linear interpolation was used in creating tool paths to avoid kinematic non linearity of parallel mechanisms and experiments are conducted using Response Surface Methodology (RSM) and gathered data is modelled by linear regression. Surface roughness results demonstrated the high machining performance of the mechanism inside available workspace.
Given its layer-based nature, additive manufacturing is known as a family of highly capable proce... more Given its layer-based nature, additive manufacturing is known as a family of highly capable processes for fabricating complex 3D geometries designed by means of evolutionary topology optimization. However, the required support structures for the overhanging features of these complex geometries can be concerningly wasteful. This article presents an approach for studying the manufacturability of the topology-optimized complex 3D parts required for additive manufacturing and finding the optimum corresponding build direction for the fabrication process. The developed methodology uses the density gradient of the design matrix created during the evolutionary topology optimization of the 3D domains to determine the optimal build orientation for additive manufacturing with the objective of minimizing the need for support structures. Highly satisfactory results are obtained by implementing the developed methodology in analytical and experimental studies, which demonstrate potential additive ...
Digital Twins are essential in establishing intelligent asset management for an asset or machine.... more Digital Twins are essential in establishing intelligent asset management for an asset or machine. They can be described as the bidirectional communication between a cyber representation and a physical asset. Predictive Maintenance is dependent on the existence of three data sets: Fault history, Maintenance/Repair History, and Machine Conditions. Current Digital Twin solutions can fail to simulate the behaviour of a faulty asset. These solutions also prove to be difficult to implement when an asset’s fault history is incomplete. This paper presents the novel methodology, LIVE Digital Twin, to develop Digital Twins with the focus of Predictive Maintenance. The four phases, Learn, Identify, Verify, and Extend are discussed. A case study analyzes the relationship of component stiffness and vibration in detecting the health of various components. The Learning phase is implemented to demonstrate the process of locating a preliminary sensor network and develop the faulty history of a Sand ...
On-line data collection from the manufactured parts is an essential element in Industry 4.0 to mo... more On-line data collection from the manufactured parts is an essential element in Industry 4.0 to monitor the production’s health, which required strong data analytics. The optical metrology-based inspection of highly reflective parts in a production line, such as parts with metallic surfaces, is a difficult challenge. As many on-line inspection paradigms require the use of optical sensors, this reflectivity can lead to large amounts of noise, rendering the scan inaccurate. This paper discusses a method for noise reduction and removal in datapoints resulting from scanning the reflective planar surfaces. Utilizing a global statistic-based iterative approach, noise is gradually removed from the dataset at increasing percentages. The change in the standard deviation of point-plane distances is examined, and an optimal amount of noisy data is removed to reduce uncertainty in representing the workpiece. The developed algorithm provides a fast and efficient method for noise reduction in opti...
This paper represents how typical advanced engineering design can be structured using a set of pa... more This paper represents how typical advanced engineering design can be structured using a set of parameters and objective functions corresponding to the nature of the problem. The set of parameters can be in different types, including integer, real, cyclic, combinatorial, interval, etc. Similarly, the objective function can be presented in various types including integer (discrete), float, and interval. The simulated annealing with crystallization heuristic can deal with all these combinations of parameters and objective functions when the crystallization heuristic presents a sensibility for real parameters. Herein, simulated annealing with the crystallization heuristic is enhanced by combining Bates and Gaussian distributions and by incorporating feedback strategies to emphasize exploration or refinement, or a combination of the two. The problems that are studied include solving an electrical impedance tomography problem with float parameters and a partially evaluated objective funct...
Anais do Congresso Brasileiro de Automática 2020, 2020
A análise de vídeos de futebol é uma área de recente interesse, particularmente a reconstrução 3D... more A análise de vídeos de futebol é uma área de recente interesse, particularmente a reconstrução 3D de partidas de futebol a partir de vídeos televisionados. São propostos três algoritmos que combinados suportarão esta reconstrução 3D de modo automático. Inicialmente, a região do jogo é determinada, que corresponde à região da imagem onde está a bola, o juiz e os jogadores. Posteriormente, as linhas do campo são determinadas utilizando a transformada de Hough, filtros de cor de geométricos são utilizados para remover falso-positivos. As intersecções entre as linhas determinam pontos invariantes que são mapeados a pontos do modelo do campo. O correto mapeamento permite corrigir a distorção perspectiva. Para determinar o mapeamento correto são realizadas combinações de correspondência entre os pontos invariantes e pontos no modelo do campo. O mapeamento do plano do gol também é determinado.
This paper presents the multiobjective optimization of the aerodynamic shape of an airfoil in vis... more This paper presents the multiobjective optimization of the aerodynamic shape of an airfoil in viscous and non-viscous flows by using the continuous adjoint optimization method. Different solvers have been developed to solve the flow and adjoint equations. The designed adjoint equations solver is capable of inverse designing the shape of the airfoil and the flap as well as optimizing their shape according to design parameters and constraints considered. The method of adjoint equations is a gradient-based method that requires the calculation of the design variables sensitivities in order to evaluate the optimal amounts for lift and drag coefficients. The main feature of this method is the ability to calculate sensitivities by solving the “adjoint equation”. In this research, the Navier-Stokes equations are discretized using continuous adjoint optimization, extracting the necessary equations for the adjoint optimization code. Resumo: Este artigo apresenta a otimização multiobjetivo da ...
Volume 1A: 35th Computers and Information in Engineering Conference, 2015
The final dimensional and geometric inaccuracies, and the resulting high surface roughness of the... more The final dimensional and geometric inaccuracies, and the resulting high surface roughness of the products have been the major problems in employing Additive Manufacturing (AM) technologies. Most of commonly used Additive manufacturing (AM) technologies are developed based on a layer-based manufacturing process to fabricate 3D models. The main critical issue in AM which reduces the surface integrity of the final products is the stair case error which happens due to layer by layer manufacturing process. A new method is presented to model the surface roughness of FDM parts based on considering a new geometry for the cusps. Variety of observations were conducted to model the exact geometry of the cusp. Considering that cusp geometry affects the surface roughness directly, the new geometry was used to predict the surface roughness distribution as a function of layer thickness and surface angle of the final FDM products. The model was validated by designing a set of experiments using 3D ...
Heavy vehicles service brakes are subject to severe loading conditions that can exceed the design... more Heavy vehicles service brakes are subject to severe loading conditions that can exceed the design conditions of safe operating performance in critical situations. Materials are prone to lose their design properties at high temperatures. Since the function of brakes is to convert the vehicle kinetic energy into heat by friction, temperature is the main variable to be considered, due to the fade of the linings composite material and cast iron drum deformation. The intent of this work is to evaluate the thermal loads of brake drums, when subjected to severe service conditions, in order to allow further analyses, mainly related to their dimensional and form variation. A case study is described, showing the possibility of the development of high temperatures and consequent risk of accidents in a real long downhill descent. Experimental data were preferably used to assure higher accuracy to the analysis. In the authors’ further work, a FEA simulation will be conducted with the data suppli...
This paper presents an experimental platform which is used to study the effect of DLC coating on ... more This paper presents an experimental platform which is used to study the effect of DLC coating on surface roughness. Variety of experiments is conducted and the effect of variation of the coating process parameters and type and combination of sub layers on the surface roughness of the coated part is discussed.
The traditional input to almost all commercially available Additive Manufacturing (AM) systems is... more The traditional input to almost all commercially available Additive Manufacturing (AM) systems is in STL (Standard Tessellation Language) format, which represents a solid model by its tessellated surfaces. This does not allow transferring the entire information of a solid model to the additive manufacturing preprocessing system. However, in some recent applications such as additive manufacturing preprocessing simulation, closed-loop of topology optimization and additive manufacturing process planning, and AM-based design optimization the full access to the solid model information is necessary. Slicing of the finite element model directly is introduced in this paper. The presented approach enables access to the entire solid model information during the AM preprocessing tasks with a focus on coupling the topology optimization in the design process with the actual manufacturing constraints.
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Papers by Ahmad Barari