Dynamische Steifigkeit und Dämpfung von Pfahlgruppen

Dynamic stiffness and damping properties of pile groups. The dynamic stiffness and damping properties of pile‐groups have been investigated in this paper. Also, the substantial influence of these properties on an economic structure and foundation design is demonstrated. The analysis has been carried out using the “Thin‐Layer‐Method”, which is a very efficient and powerful analysis procedure in frequency domain.     

Evaluation of acoustic and dynamic behaviour of ethylene vinyl acetate panels

Ethylene vinyl acetate panels, with high vinyl acetate content and a closed‐cell structure, were studied through various experimental techniques as a first approach to evaluate the vibrational and acoustic behaviour of ethylene vinyl acetate panels for building applications. Test specimens, with a variety of densities and thicknesses were tested to evaluate the influence of these two parameters on acoustic impedance, sound transmission loss, dynamic stiffness and attenuation of vibrations. The results obtained shows sound transmission loss values for frequencies up to 2500 Hz with a maximum of about 63.7 dB, the dynamic stiffness results presented a wide range, with a maximum value of 350 MN/m³ and a minimum value of 23.3 MN/m³.On the other hand the lack of pore in the surface produce a high acoustic impedance. It can be concluded that ethylene vinyl acetate presents appropriate characteristics, mainly as an acoustic and vibration isolating material, for floorings and light partitions.     

Concept of energy efficient technological system: Machine tool – cutting tool – workpiece

This study deals with the concept of increasing energy efficiency by means of decreasing the energetic losses by using advanced composite machine tool components and interfaces characterized by low friction, and high wear resistance. Moreover, this study provides experimental results of damping property measurements and characteristic time domain curves of the fibre, particle, and sandwich composites, underlining the advantages of such composite types in terms of dynamic loading. Furthermore, it provides an analysis on the usage of thin films (coatings) and energy consumption in terms of cutting conditions. The study analyses the cutting tool geometry and shape of cutting edge that positively affect the cutting forces and chip flow direction, and avoid the energy-intensive restricted cutting effect. Respecting the results of the analyses of mentioned effects contributes to increasing the energy efficiency of the machine tool-cutting tool-workpiece system.     

Polymer Bonded Ferrite Materials as EMC Components

Polymer bonded ferrites composed of a mixture of Mn‐Zn ferrites or Ni‐Zn ferrites in a polymer binder (PE, PA) were prepared and tested as electromagnetic‐wave absorbing materials. Test samples and cases were prepared by hot or injection molding. Permeability spectra show loss contributions in the frequency range 100‐1000 MHz. Absorption measurements of injection molded polymer‐ferrite cases display a 3‐5 dB better attenuation characteristics compared to graphite‐loaded polyamide housings.