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1.
Analysis of a strain rate field in cold formed material using the visioplasticity method
Leo Gusel, Rebeka Rudolf, Borut Kosec, 2009, short scientific article

Abstract: In this paper the visioplasticity method is used to find the complete velocity and strain rate distributions from the experimental data, using the finite-difference method. The data about values of strain rates in plastic re- gion of the material is very important for calculating stresses and the prediction of product quality. Specimens of copper alloy were extruded with different lubricants and different coefficients of friction and then the strain rate distributions were analysed and compared. Significant differences in velocity and strain rate distributions were obtained in some regions at the exit of the deformed zone.
Keywords: forward extrusion, copper alloy, visioplasticity, strain rate, lubrication
Published: 03.07.2017; Views: 328; Downloads: 73
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Dependence of material characteristics on lubrication in bulk forming process
Leo Gusel, 2009, published scientific conference contribution

Abstract: In the paper the influence of coefficient of friction (lubricant) on different properties of cold formed material has been examined. Tensile tests, hardness measurements and electrical conductivity measurements were performed.In the frame of the experimental work the process of cold forward extrusion of a cylinder made from copper alloy was investigated. The specimens were extruded at four different lubricants coefficients of friction. The results have shown that use of different lubricators with different coefficients of friction can have effects on the material properties during and after cold forming process.
Keywords: lubrication, cold forming, copper alloy, mechanical properties
Published: 31.05.2012; Views: 1169; Downloads: 14
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4.
Modeling of impact toughness of cold formed material by genetic programming
Leo Gusel, Miran Brezočnik, 2006, original scientific article

Abstract: In the paper, an approach completely different from the conventional methods for determination of accurate models for the change of properties of cold formed material, is presented. This approach is genetic programming (GP) method which is based on imitation of natural evolution of living organisms. The main characteristic of GP is its non-deterministic way of computing. No assumptions about the form and size of expressions were made in advance, but they were left to the self organization and intelligence of evolutionary process. First, copper alloy rods were cold drawn under different conditions and then impact toughness of cold drawn specimens was determined by Charpy tests. The values of independent variables (effective strain, coefficient of friction) influence the value of the dependent variable, impact toughness. On the basis of training data, different prediction models for impact toughness were developed by GP. Only the best models, gained by genetic programming were presented in the paper. Accuracy of the best models was proved with the testing data set. The comparison between deviation of genetic model results and regression model results concerning the experimental results has showed that genetic models are more precise and more varied then regression models.
Keywords: metal forming, genetic programming, evolutionary computing, impact toughness, copper alloy, modelling
Published: 30.05.2012; Views: 1688; Downloads: 89
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