The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
Marion Merklein - One of the best experts on this subject based on the ideXlab platform.
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comprehensive approach for process modeling and optimization in cold forging considering interactions between process tool and press
Journal of Materials Processing Technology, 2013Co-Authors: T Krois, U Engel, Marion MerkleinAbstract:Abstract In this paper a comprehensive approach is presented for the consideration of the interactions between process, tool and machine during the design of cold forging tools and processes by simulation. The interactions occur due to the high forming loads in cold forging and yield considerable Deflections of press and tooling system. These, in turn, influence the workpiece dimensions. The entire approach comprises an efficient determination of the Deflection Characteristic of stroke-controlled press and tooling system and its condensed modeling in combination with the FE simulation of a cold forging process. Building on that, an analytic process model is developed that is based on a set of variant simulations. It permits an optimization of the values of influencing parameters to achieve high workpiece accuracy without subsequent adjusting effort. Initially, the analytic process model required a high number of variant simulations. By acquiring knowledge on the specific process behavior in an analysis of effects and interactions a considerable reduction of simulation runs by a factor of almost 12 was achieved in the case study on full forward extrusion. The approach is supplemented by an analytic model of the die load. In addition, scatter and uncertainties of target values depending on the ones of the influencing parameters can be estimated by applying the Monte Carlo method to the analytic process model.
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process modeling in cold forging considering the process tool machine interactions
NUMIFORM 2010: Proceedings of the 10th International Conference on Numerical Methods in Industrial Forming Processes Dedicated to Professor O. C. Zien, 2010Co-Authors: Thomas Kroiss, U Engel, Marion MerkleinAbstract:In this paper, a methodic approach is presented for the determination and modeling of the axial Deflection Characteristic for the whole system of stroke‐controlled press and tooling system. This is realized by a combination of experiment and FE simulation. The press Characteristic is uniquely measured in experiment. The tooling system Characteristic is determined in FE simulation to avoid experimental investigations on various tooling systems. The stiffnesses of press and tooling system are combined to a substitute stiffness that is integrated into the FE process simulation as a spring element. Non‐linear initial effects of the press are modeled with a constant shift factor. The approach was applied to a full forward extrusion process on a press with C‐frame. A comparison between experiments and results of the integrated FE simulation model showed a high accuracy of the FE model. The simulation model with integrated Deflection Characteristic represents the entire process behavior and can be used for the calculation of a mathematical process model based on variant simulations and response surfaces. In a subsequent optimization step, an adjusted process and tool design can be determined, that compensates the influence of the Deflections on the workpiece dimensions leading to high workpiece accuracy. Using knowledge on the process behavior, the required number of variant simulations was reduced.
U Engel - One of the best experts on this subject based on the ideXlab platform.
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comprehensive approach for process modeling and optimization in cold forging considering interactions between process tool and press
Journal of Materials Processing Technology, 2013Co-Authors: T Krois, U Engel, Marion MerkleinAbstract:Abstract In this paper a comprehensive approach is presented for the consideration of the interactions between process, tool and machine during the design of cold forging tools and processes by simulation. The interactions occur due to the high forming loads in cold forging and yield considerable Deflections of press and tooling system. These, in turn, influence the workpiece dimensions. The entire approach comprises an efficient determination of the Deflection Characteristic of stroke-controlled press and tooling system and its condensed modeling in combination with the FE simulation of a cold forging process. Building on that, an analytic process model is developed that is based on a set of variant simulations. It permits an optimization of the values of influencing parameters to achieve high workpiece accuracy without subsequent adjusting effort. Initially, the analytic process model required a high number of variant simulations. By acquiring knowledge on the specific process behavior in an analysis of effects and interactions a considerable reduction of simulation runs by a factor of almost 12 was achieved in the case study on full forward extrusion. The approach is supplemented by an analytic model of the die load. In addition, scatter and uncertainties of target values depending on the ones of the influencing parameters can be estimated by applying the Monte Carlo method to the analytic process model.
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optimization of tool and process design for the cold forging of net shape parts by simulation
2013Co-Authors: T Krois, U EngelAbstract:As a result of the research work in this project, a comprehensive approach is presented for the consideration of the interactions between process, tool and machine in the FE-based design of cold forging tools and processes: The approach comprises an efficient determination of the Deflection Characteristic of press and tooling system and its subsequent condensed modeling in combination with the FE simulation of a cold forging process. Then, based on a set of simulations, a parametric process model is developed. It permits an optimization of the values of influencing parameters to achieve high workpiece accuracy considering the interactions. By acquiring and, afterwards, applying knowledge on the process behavior, the required number of simulations for the parametric process model and the optimization can be reduced considerably. The approach can be completed by using the parametric process model for estimating scatter and uncertainties of target values depending on those of the influencing parameters.
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process modeling in cold forging considering the process tool machine interactions
NUMIFORM 2010: Proceedings of the 10th International Conference on Numerical Methods in Industrial Forming Processes Dedicated to Professor O. C. Zien, 2010Co-Authors: Thomas Kroiss, U Engel, Marion MerkleinAbstract:In this paper, a methodic approach is presented for the determination and modeling of the axial Deflection Characteristic for the whole system of stroke‐controlled press and tooling system. This is realized by a combination of experiment and FE simulation. The press Characteristic is uniquely measured in experiment. The tooling system Characteristic is determined in FE simulation to avoid experimental investigations on various tooling systems. The stiffnesses of press and tooling system are combined to a substitute stiffness that is integrated into the FE process simulation as a spring element. Non‐linear initial effects of the press are modeled with a constant shift factor. The approach was applied to a full forward extrusion process on a press with C‐frame. A comparison between experiments and results of the integrated FE simulation model showed a high accuracy of the FE model. The simulation model with integrated Deflection Characteristic represents the entire process behavior and can be used for the calculation of a mathematical process model based on variant simulations and response surfaces. In a subsequent optimization step, an adjusted process and tool design can be determined, that compensates the influence of the Deflections on the workpiece dimensions leading to high workpiece accuracy. Using knowledge on the process behavior, the required number of variant simulations was reduced.
T Krois - One of the best experts on this subject based on the ideXlab platform.
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comprehensive approach for process modeling and optimization in cold forging considering interactions between process tool and press
Journal of Materials Processing Technology, 2013Co-Authors: T Krois, U Engel, Marion MerkleinAbstract:Abstract In this paper a comprehensive approach is presented for the consideration of the interactions between process, tool and machine during the design of cold forging tools and processes by simulation. The interactions occur due to the high forming loads in cold forging and yield considerable Deflections of press and tooling system. These, in turn, influence the workpiece dimensions. The entire approach comprises an efficient determination of the Deflection Characteristic of stroke-controlled press and tooling system and its condensed modeling in combination with the FE simulation of a cold forging process. Building on that, an analytic process model is developed that is based on a set of variant simulations. It permits an optimization of the values of influencing parameters to achieve high workpiece accuracy without subsequent adjusting effort. Initially, the analytic process model required a high number of variant simulations. By acquiring knowledge on the specific process behavior in an analysis of effects and interactions a considerable reduction of simulation runs by a factor of almost 12 was achieved in the case study on full forward extrusion. The approach is supplemented by an analytic model of the die load. In addition, scatter and uncertainties of target values depending on the ones of the influencing parameters can be estimated by applying the Monte Carlo method to the analytic process model.
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optimization of tool and process design for the cold forging of net shape parts by simulation
2013Co-Authors: T Krois, U EngelAbstract:As a result of the research work in this project, a comprehensive approach is presented for the consideration of the interactions between process, tool and machine in the FE-based design of cold forging tools and processes: The approach comprises an efficient determination of the Deflection Characteristic of press and tooling system and its subsequent condensed modeling in combination with the FE simulation of a cold forging process. Then, based on a set of simulations, a parametric process model is developed. It permits an optimization of the values of influencing parameters to achieve high workpiece accuracy considering the interactions. By acquiring and, afterwards, applying knowledge on the process behavior, the required number of simulations for the parametric process model and the optimization can be reduced considerably. The approach can be completed by using the parametric process model for estimating scatter and uncertainties of target values depending on those of the influencing parameters.
Michael J T Thompson - One of the best experts on this subject based on the ideXlab platform.
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shock sensitivity in shell like structures with simulations of spherical shell buckling
International Journal of Bifurcation and Chaos, 2016Co-Authors: Michael J T Thompson, Jan SieberAbstract:Under increasing compression, an unbuckled shell is in a metastable state which becomes increasingly precarious as the buckling load is approached. So to induce premature buckling, a lateral disturbance will have to overcome a decreasing energy barrier which reaches zero at buckling. Two archetypal problems that exhibit a severe form of this behavior are the axially-compressed cylindrical shell and the externally pressurized spherical shell. Focusing on the cylinder, a nondestructive technique was recently proposed to estimate the “shock-sensitivity” of a laboratory specimen using a lateral probe to measure the nonlinear load-Deflection Characteristic. If a symmetry-breaking bifurcation is encountered on the path, computer simulations showed how this can be suppressed by a controlled secondary probe. Here, we extend our understanding by assessing in general terms how a single control can capture remote saddle solutions: in particular, how a symmetric probe could locate an asymmetric solution. Then, more s...
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shock sensitivity in shell like structures with simulations of spherical shell buckling
arXiv: Soft Condensed Matter, 2015Co-Authors: Michael J T Thompson, Jan SieberAbstract:Under increasing compression, an unbuckled shell is in a metastable state which becomes increasingly precarious as the buckling load is approached. So to induce premature buckling a lateral disturbance will have to overcome a decreasing energy barrier which reaches zero at buckling. Two archetypal problems that exhibit a severe form of this behaviour are the axially-compressed cylindrical shell and the externally pressurized spherical shell. Focussing on the cylinder, a non-destructive technique was recently proposed to estimate the 'shock sensitivity' of a laboratory specimen using a lateral probe to measure the nonlinear load-Deflection Characteristic. If a symmetry-breaking bifurcation is encountered on the path, computer simulations showed how this can be suppressed by a controlled secondary probe. Here, we extend our understanding by assessing in general terms how a single control can capture remote saddle solutions: in particular how a symmetric probe could locate an asymmetric solution. Then, more specifically, we analyse the spherical shell with point and ring probes, to test the procedure under challenging conditions to assess its range of applicability. Rather than a bifurcation, the spherical shell offers the challenge of a de-stabilizing fold (limit point) under the rigid control of the probe.
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advances in shell buckling theory and experiments
arXiv: Pattern Formation and Solitons, 2014Co-Authors: Michael J T ThompsonAbstract:In a recent feature article in this journal, co-authored by Gert van der Heijden, I described the static-dynamic analogy and its role in understanding the localized post-buckling of shell-like structures, looking exclusively at integrable systems. We showed the true significance of the Maxwell energy criterion load in predicting the sudden onset of 'shock sensitivity' to lateral disturbances. The present paper extends the survey to cover non-integrable systems, such as thin compressed shells. These exhibit spatial chaos, generating a multiplicity of localized paths (and escape routes) with complex snaking and laddering phenomena. The final theoretical contribution shows how these concepts relate to the response and energy barriers of an axially compressed cylindrical shell. After surveying NASA's current shell-testing programme, a new non-destructive technique is proposed to estimate the 'shock sensitivity' of a laboratory specimen that is in a compressed meta-stable state before buckling. A probe is used to measure the nonlinear load-Deflection Characteristic under a rigidly applied lateral displacement. Sensing the passive resisting force, it can be plotted in real time against the displacement, displaying an equilibrium path along which the force rises to a maximum and then decreases to zero: having reached the free state of the shell that forms a mountain-pass in the potential energy. The area under this graph gives the energy barrier against lateral shocks. The test is repeated at different levels of the overall compression. If a symmetry-breaking bifurcation is encountered on the path, computer simulations show how this can be supressed by a controlled secondary probe tuned to deliver zero force on the shell.
Jan Sieber - One of the best experts on this subject based on the ideXlab platform.
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shock sensitivity in shell like structures with simulations of spherical shell buckling
International Journal of Bifurcation and Chaos, 2016Co-Authors: Michael J T Thompson, Jan SieberAbstract:Under increasing compression, an unbuckled shell is in a metastable state which becomes increasingly precarious as the buckling load is approached. So to induce premature buckling, a lateral disturbance will have to overcome a decreasing energy barrier which reaches zero at buckling. Two archetypal problems that exhibit a severe form of this behavior are the axially-compressed cylindrical shell and the externally pressurized spherical shell. Focusing on the cylinder, a nondestructive technique was recently proposed to estimate the “shock-sensitivity” of a laboratory specimen using a lateral probe to measure the nonlinear load-Deflection Characteristic. If a symmetry-breaking bifurcation is encountered on the path, computer simulations showed how this can be suppressed by a controlled secondary probe. Here, we extend our understanding by assessing in general terms how a single control can capture remote saddle solutions: in particular, how a symmetric probe could locate an asymmetric solution. Then, more s...
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shock sensitivity in shell like structures with simulations of spherical shell buckling
arXiv: Soft Condensed Matter, 2015Co-Authors: Michael J T Thompson, Jan SieberAbstract:Under increasing compression, an unbuckled shell is in a metastable state which becomes increasingly precarious as the buckling load is approached. So to induce premature buckling a lateral disturbance will have to overcome a decreasing energy barrier which reaches zero at buckling. Two archetypal problems that exhibit a severe form of this behaviour are the axially-compressed cylindrical shell and the externally pressurized spherical shell. Focussing on the cylinder, a non-destructive technique was recently proposed to estimate the 'shock sensitivity' of a laboratory specimen using a lateral probe to measure the nonlinear load-Deflection Characteristic. If a symmetry-breaking bifurcation is encountered on the path, computer simulations showed how this can be suppressed by a controlled secondary probe. Here, we extend our understanding by assessing in general terms how a single control can capture remote saddle solutions: in particular how a symmetric probe could locate an asymmetric solution. Then, more specifically, we analyse the spherical shell with point and ring probes, to test the procedure under challenging conditions to assess its range of applicability. Rather than a bifurcation, the spherical shell offers the challenge of a de-stabilizing fold (limit point) under the rigid control of the probe.