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Relation between shakedown and shape memory of metallic materials considering their mesoscale and atomic scale substructures

Kafka V., Vokoun D.

Archives of Mechanics

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2009

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Vol. 61, nr 6

445-458

EN

Shakedown (SD) and shape memory (SM) - generally looked upon as two different phenomena - are shown to have close relations from the point of view of their mechanisms, if considering the respective mesoscale processes on the one hand and the atomic scale processes on the other hand. With the use of the general mesomechanical concept of the first author, their constitutive equations are formulated using the same basic formulae, but with different meanings of the symbols. Constitutive equations are based on the description of internal stresses, in the case of SD on the mesoscale, in the case of SM on the atomic scale. Whereas in the case of SD, plastic deformation means shifting of atomic blocks and changing atomic neighbors, in the case of a diffusionless SM the atomic neighbors are maintained, what simplifies the analysis.

2

Use of technical and economic analysis in production of liquid metal in foundries

Kafka V., Figala V., Nykodýmowá V., Herzán M., Pelucha B.

Archives of Foundry Engineering

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2008

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Vol. 8, iss. 2

71-76

EN

The paper in its introduction describes main principles of technical and economic analysis the application of which leads to determination of potential costs savings and subsequently to costs reduction. The application of the method is illustrated by an example of production of three types of steel grades for cast steel produced in five tons electric arc furnace. With the aid of the calculation model, incomplete costs of selective complex of the melts were determined (30 melts within the first phase and 260 in the second one). Incomplete costs and selected physical indicators (e.g. melting time, electrical energy consumption etc.) were subsequently compiled with the aid of statistical analysis. After that, the individual selective complexes were compared with each other (according to melters; first and second melt on the shift; melting with one or more charge basket; days in a week). The detailed analysis of these outcomes resulted in many particular recommendations how to reduce the costs in the foundry. The final recommendation for the melting shop is a proposal to introduce continuous monitoring of costs.

3

Control of cost heftiness of castings production with improvement of PROJECTS

Kafka V., Nykodýmowá V., Szmek V., Lána I., Doupovec D., Knirsch V., Martinák R., Fošum J., Novobílský M., Jochim R.

Archives of Foundry Engineering

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2008

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Vol. 8, iss. 2

77-80

EN

The Specialized Commission for Economy of Czech Foundrymen Society in the Czech Republic systematically follows a solution of particular phases of castings production from iron and non-ferrous metals already for eighth years. These separate studies are uniformly aimed at cost analysis of chosen phases of castings production. The analysis of cost heftiness and recommendations for concrete remedies for particular foundries are the results. The contribution is aimed at transparent description of topics of the PROJECTS I - VII. Further on it describes in more details the PROJECT VIII, especially the costs of preparation of moulding mixtures. The team solving this problem gathers the results of costs comparison of preparation of fifteen moulding mixtures in five Czech foundries in this project. The inquiry topics are bentonite moulding mixtures (unit, pattern, and heap), further on the self-setting mixtures (with waterglass and furane). The inquiry is closed with Cold-Box-Amine core mixture. The evaluation is aimed both at own cost comparison, and at prediction of moulding mixture costs resulting from knowledge of their structure. Further on it deals with the future growth of waste costs. Subsequently, the possibilities of costs specification concerning to power consumption are viewed. Very interesting results are described for studying the relations of costs of moulding mixtures and particular castings. Questions of determining the price of used return moulding mixture are remarkable too. The way to achieve another costs reduction is also the investigation of costs changeableness for mixing the mixtures. The work ends with summary suggestion of next progress.