Materials and machining trends in terms of the existing axioms of the machining theory

The paper provides new insight into existing axioms of theory of machining. The existing theory of metalworking was based on the development of cutting materials during the 20^th century. In particular, the improvement of cutting materials, the new special materials and progressive technologies and the trends to increase cutting speed call for a review of existing definitions and relations. Appling previously defined relations between cutting conditions and results of machining, the inaccuracies occur and this may lead to an incorrect choice of cutting conditions in the specific conditions of machining. The paper analyses existing well‐known equations used in practice and on the basis of extensive experimental analysis it modifies them. Furthermore, the paper concerns the evaluation of physical and technological parameters, such as chips compression, machined surface roughness, cutting forces, cutting tool‐wear and tool‐life.     

Influence of cooling rates on temperatures phase transitions and on microstructure of aluminium alloy EN AW‐5083

The casting of different forms and dimensions of aluminium alloy EN WA‐5083 test samples and the usage of different types of mould materials resulted in achieving different cooling rates of samples. The methods used were simple thermal analysis, using casting into a measuring cell made by the Croning process and using casting into a cone‐shaped measuring cell, as well as simultaneous thermal analysis using the method of differential scanning calorimetry. Significant temperature phase transitions and times of solidification were determined, and the dependence model of the solidification time on the sample cooling rate was obtained. Determining the mean number of grains per unit area on samples after having performed the simple thermal analysis and differential scanning calorimetry makes it possible to develop a dependence model of the mean number of grains per unit area on the cooling rate. These models are the basis for carrying out numerical simulations of solidification and microstructure development in the cone‐shaped measuring cell, and the comparison of the distribution of the mean number of grains per unit area obtained by simulation with the one obtained experimentally. The obtained results represent a part of the preliminary tests of the microstructure development of industrially cast ingots of EN AW‐5083 alloy depending on the local ingot cooling rate.     

Kontinuierliche faseroptische Dehnungsmessung im Stahlbetonbau

Distributed fiber‐optic strain measurement – application in reinforced concrete members Distributed fiber optic measurement based on Rayleigh scattering is a technique with new possibilities in the field of analysis and interpretation of experiments. However, the application is challenging and requires a lot of experience and practice. The measurement technique will be briefly described and subsequently the authors will show and explain the potential as well as challenges and limits of application based on two small experiments.     

Ein neuer Ansatz zur Charakterisierung der Flüssigphasenadsorption an Aktivkohlen

Activated carbons are widely applicable in industrial adsorption processes. However, characterization of their surface properties is problematic due to the number of different source materials and variations in production processes. Here, a model of the carbon surface derived that is based on the knowledge of fundamental molecular interactions on carbon surfaces. Adsorption isotherms of selected probe molecules are measured on different activated carbons and discussed how the model can be applied in the characterization of the surface properties of activated carbons.