Eduardo Gaertner - Academia.edu (original) (raw)
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Papers by Eduardo Gaertner
Key Engineering Materials, 2015
The fretting is responsible for many failures of components in the industry. It is present in ass... more The fretting is responsible for many failures of components in the industry. It is present in assemblies like rivet and screw fixture, dovetailjoint, shaft and hub with key, and all connections of two bodies with a contact force and a small induced relative displacement. Topic of studies for decades, the researchers perform experimental tests with some simplification in order to accelerate the phenomenon, some times using standard devices or creating dedicated machines for better representing the behavior of the desired components. There are a few studies with thin sheets, in which the fretting fatigue has more impact because a small reduction of the cross section due to the wear of crack results in a significant increase of stress and rate of crack propatation, decresing the number of cycles until failure. In this work, it wasbuild a device to generate the fretting fatigue with two different shape of contact pad. The specimen is a stainless steel sheet thickness 0.152mm, which fractures and surfaces were analyzed using the SEM and white light interferometer to understand the fractures.
In this work, aspects of discretization errors associated with finite volume (FV) and equivalent ... more In this work, aspects of discretization errors associated with finite volume (FV) and equivalent finite element (FE) modelling strategies are discussed within the framework of polymer melt flow. The computational approaches are based on the generalized Newtonian model in conjunction with Cross constitutive equation. The numerical examples illustrate one and two-dimensional fluid flows, in which the latter is discretized using structured quadrilateral elements / volumes. A study on the best strategy to compute non-linear viscosities at control volume boundaries is also presented for FV. Based on well established a posteriori error estimation techniques, it is demonstrated that, in this class of problems, FV discretization errors and differences between FE and FV solutions are greatly affected by the scheme used to compute the FV non-linear coefficients at the control volume surfaces. Simulations for rectangular channels show that FE yields smaller global errors then FV for velocity a...
Finite element analysis (FEA) is a common tool used within many areas of engineering to indicate ... more Finite element analysis (FEA) is a common tool used within many areas of engineering to indicate the behavior of a component before production. However, results for most analyses only contemplate the nominal geometry, and do not take product variation during manufacturing and assembly into consideration. These differences can have a significant effect on the structural response and thus not reach the desired performance. To eliminate these doubts, it is possible to exchange the deterministic model for a robust design. Robust design is an analytical method of evaluating the range of product variation due to the uncertainties in the model. Based on a probabilistic characterization, this technique is helpful in determining product quality, predicting its behavior and deviation, not just when everything is in nominal case. It also indicates the design variables responsible for most of the result variations, important for achieving a particular probabilistic level. The present work deals with the case study of a discharge tube structural response, considering the variation of some dimensions. As a result, it will be apparent which dimensions have the greatest influence on the design specification and which tolerances can be increased in order to reduce manufacturing costs, while maintaining the balance between performance and cost.
A linear elastic model is often not appropriate for numerical simulations of conformed mechanical... more A linear elastic model is often not appropriate for numerical simulations of conformed mechanical components. Such processes have large permanent deformations, and require material models that account for the relationship between stress and strain, along with the influence of temperature and strain rate.. Important parameters are mesh quality, solver type, contact behavior, boundary conditions and the material model. Also, when the properties are unknown and the data available in the literature is inadequate, lab tests are indispensable. The easiest and most common test is the tension test. It provides information, such as stress-strain curve, Young modulus, yield and ultimate stress. This work proposes to analyze numerical results using MISO and BISO models, with experimental data from a tension test. This problem involves compressing a cylinder against two flat surfaces. It is validated with actual tests, where the load versus axial and radial displacement are measured during load...
Accuracy analysis is fundamental to ascertain the reliability of a numerical solution of any indu... more Accuracy analysis is fundamental to ascertain the reliability of a numerical solution of any industrial operation. The analysis is often complex due to different error sources. In this work, two strategies to assess the discretization errors is discussed: (i) Richardson extrapolation and (ii) a posteriori error estimation based on projecting/smoothing techniques. The former utilises three nested meshes whereas the latter is based on the post-processing of the problem solution over only one mesh. The model accounts for the full interaction between the thermal effects caused by viscous heating and the momentum diffusion effects dictated by a shear rate and temperature-dependent viscosity.
Considering the current market environment, where competition can not be denied and the developme... more Considering the current market environment, where competition can not be denied and the development time must be even short than ever, the use of advanced engineering tools is mandatory. New products must reach the market as soon as possible otherwise the opportunity will be left for the competitors. Furthermore, the cost reduction approach during the design is a mandatory effort and must be considered. Concerning those issues, advanced CAE tools have important duty to accomplish this requirement. Using virtual models created by CAD system and commercial or inhouse engineering software (CAE), mainly Finite Element Method (FEM), it is possible to simulate the structural behavior of a mechanical component before its prototyping. Prototypes have high cost in terms of money, time and production. The objective of this work is to present some FEM applications on compressor components, showing its importance and power in the development of this kind of product.
Finite element analysis (FEA) is a common tool used within many areas of engineering to indicate ... more Finite element analysis (FEA) is a common tool used within many areas of engineering to indicate the behavior of a component before production. However, results for most analyses only contemplate the nominal geometry, and do not take product variation during manufacturing and assembly into consideration. These differences can have a significant effect on the structural response and thus not reach the desired performance. To eliminate these doubts, it is possible to exchange the deterministic model for a robust design. Robust design is an analytical method of evaluating the range of product variation due to the uncertainties in the model. Based on a probabilistic characterization, this technique is helpful in determining product quality, predicting its behavior and deviation, not just when everything is in nominal case. It also indicates the design variables responsible for most of the result variations, important for achieving a particular probabilistic level. The present work deals with the case study of a discharge tube structural response, considering the variation of some dimensions. As a result, it will be apparent which dimensions have the greatest influence on the design specification and which tolerances can be increased in order to reduce manufacturing costs, while maintaining the balance between performance and cost.
Communications in Numerical Methods in Engineering, 2006
This work aims at evaluating the discretization errors associated to the ÿnite volume and ÿnite e... more This work aims at evaluating the discretization errors associated to the ÿnite volume and ÿnite element methods of polymer melt ow in closed channels. Two strategies are discussed: (i) Richardson extrapolation and (ii) a posteriori error estimation based on projection=smoothing techniques. The numerical model accounts for the full interaction between the thermal e ects caused by viscous heating and the momentum di usion e ects dictated by a shear rate and temperature-dependent constitutive model. The simulations have been performed for the commercial polymer Polyacetal POM-M90-44.
Key Engineering Materials, 2015
The fretting is responsible for many failures of components in the industry. It is present in ass... more The fretting is responsible for many failures of components in the industry. It is present in assemblies like rivet and screw fixture, dovetailjoint, shaft and hub with key, and all connections of two bodies with a contact force and a small induced relative displacement. Topic of studies for decades, the researchers perform experimental tests with some simplification in order to accelerate the phenomenon, some times using standard devices or creating dedicated machines for better representing the behavior of the desired components. There are a few studies with thin sheets, in which the fretting fatigue has more impact because a small reduction of the cross section due to the wear of crack results in a significant increase of stress and rate of crack propatation, decresing the number of cycles until failure. In this work, it wasbuild a device to generate the fretting fatigue with two different shape of contact pad. The specimen is a stainless steel sheet thickness 0.152mm, which fractures and surfaces were analyzed using the SEM and white light interferometer to understand the fractures.
In this work, aspects of discretization errors associated with finite volume (FV) and equivalent ... more In this work, aspects of discretization errors associated with finite volume (FV) and equivalent finite element (FE) modelling strategies are discussed within the framework of polymer melt flow. The computational approaches are based on the generalized Newtonian model in conjunction with Cross constitutive equation. The numerical examples illustrate one and two-dimensional fluid flows, in which the latter is discretized using structured quadrilateral elements / volumes. A study on the best strategy to compute non-linear viscosities at control volume boundaries is also presented for FV. Based on well established a posteriori error estimation techniques, it is demonstrated that, in this class of problems, FV discretization errors and differences between FE and FV solutions are greatly affected by the scheme used to compute the FV non-linear coefficients at the control volume surfaces. Simulations for rectangular channels show that FE yields smaller global errors then FV for velocity a...
Finite element analysis (FEA) is a common tool used within many areas of engineering to indicate ... more Finite element analysis (FEA) is a common tool used within many areas of engineering to indicate the behavior of a component before production. However, results for most analyses only contemplate the nominal geometry, and do not take product variation during manufacturing and assembly into consideration. These differences can have a significant effect on the structural response and thus not reach the desired performance. To eliminate these doubts, it is possible to exchange the deterministic model for a robust design. Robust design is an analytical method of evaluating the range of product variation due to the uncertainties in the model. Based on a probabilistic characterization, this technique is helpful in determining product quality, predicting its behavior and deviation, not just when everything is in nominal case. It also indicates the design variables responsible for most of the result variations, important for achieving a particular probabilistic level. The present work deals with the case study of a discharge tube structural response, considering the variation of some dimensions. As a result, it will be apparent which dimensions have the greatest influence on the design specification and which tolerances can be increased in order to reduce manufacturing costs, while maintaining the balance between performance and cost.
A linear elastic model is often not appropriate for numerical simulations of conformed mechanical... more A linear elastic model is often not appropriate for numerical simulations of conformed mechanical components. Such processes have large permanent deformations, and require material models that account for the relationship between stress and strain, along with the influence of temperature and strain rate.. Important parameters are mesh quality, solver type, contact behavior, boundary conditions and the material model. Also, when the properties are unknown and the data available in the literature is inadequate, lab tests are indispensable. The easiest and most common test is the tension test. It provides information, such as stress-strain curve, Young modulus, yield and ultimate stress. This work proposes to analyze numerical results using MISO and BISO models, with experimental data from a tension test. This problem involves compressing a cylinder against two flat surfaces. It is validated with actual tests, where the load versus axial and radial displacement are measured during load...
Accuracy analysis is fundamental to ascertain the reliability of a numerical solution of any indu... more Accuracy analysis is fundamental to ascertain the reliability of a numerical solution of any industrial operation. The analysis is often complex due to different error sources. In this work, two strategies to assess the discretization errors is discussed: (i) Richardson extrapolation and (ii) a posteriori error estimation based on projecting/smoothing techniques. The former utilises three nested meshes whereas the latter is based on the post-processing of the problem solution over only one mesh. The model accounts for the full interaction between the thermal effects caused by viscous heating and the momentum diffusion effects dictated by a shear rate and temperature-dependent viscosity.
Considering the current market environment, where competition can not be denied and the developme... more Considering the current market environment, where competition can not be denied and the development time must be even short than ever, the use of advanced engineering tools is mandatory. New products must reach the market as soon as possible otherwise the opportunity will be left for the competitors. Furthermore, the cost reduction approach during the design is a mandatory effort and must be considered. Concerning those issues, advanced CAE tools have important duty to accomplish this requirement. Using virtual models created by CAD system and commercial or inhouse engineering software (CAE), mainly Finite Element Method (FEM), it is possible to simulate the structural behavior of a mechanical component before its prototyping. Prototypes have high cost in terms of money, time and production. The objective of this work is to present some FEM applications on compressor components, showing its importance and power in the development of this kind of product.
Finite element analysis (FEA) is a common tool used within many areas of engineering to indicate ... more Finite element analysis (FEA) is a common tool used within many areas of engineering to indicate the behavior of a component before production. However, results for most analyses only contemplate the nominal geometry, and do not take product variation during manufacturing and assembly into consideration. These differences can have a significant effect on the structural response and thus not reach the desired performance. To eliminate these doubts, it is possible to exchange the deterministic model for a robust design. Robust design is an analytical method of evaluating the range of product variation due to the uncertainties in the model. Based on a probabilistic characterization, this technique is helpful in determining product quality, predicting its behavior and deviation, not just when everything is in nominal case. It also indicates the design variables responsible for most of the result variations, important for achieving a particular probabilistic level. The present work deals with the case study of a discharge tube structural response, considering the variation of some dimensions. As a result, it will be apparent which dimensions have the greatest influence on the design specification and which tolerances can be increased in order to reduce manufacturing costs, while maintaining the balance between performance and cost.
Communications in Numerical Methods in Engineering, 2006
This work aims at evaluating the discretization errors associated to the ÿnite volume and ÿnite e... more This work aims at evaluating the discretization errors associated to the ÿnite volume and ÿnite element methods of polymer melt ow in closed channels. Two strategies are discussed: (i) Richardson extrapolation and (ii) a posteriori error estimation based on projection=smoothing techniques. The numerical model accounts for the full interaction between the thermal e ects caused by viscous heating and the momentum di usion e ects dictated by a shear rate and temperature-dependent constitutive model. The simulations have been performed for the commercial polymer Polyacetal POM-M90-44.