An interest in vehicle efficiency improvement drives a need for research in the field of light metal alloys. Current industrially-available technologies do not include warm-forming of metal alloy sheet materials. The obstacles to the technology may be potentially overcome with granular media, which could be used as an alternative force transfer medium. However, some granular material properties like force chain formation require further investigation before forming technology using granular media may be developed. Throughout the course of this study, a direct shear cell instrument was designed and fabricated. This instrument was used to measure the basic mechanical properties of granular media. A 3D CAD model of the direct shear cell instrument and operating procedures are presented in this study. Different granular materials, such as steel bearing balls and sand, were tested under conditions simulating granular media flow behavior expected for the working medium in warm-forming of metal alloys sheet materials. The experiments were conducted under both static and oscillating normal loads. The static load experiments were conducted for various normal loads and shear rates, and oscillating normal load experiments were conducted under various oscillation frequencies, average normal loads and load amplitudes. During dense-packed spherical granular media flow experiments, shear stress oscillations were observed. These are attributed to the force-chain jamming behavior occurring within the granular media structure. It was also observed that granular media flow properties can be controlled by an oscillating normal load applied to the granular media. From the experimental and simulation studies it may be concluded that normal load oscillations should enhance granular media flow, which could be a great advantage for using granular media as working fluid for sheet metal forming. / text

Ce travail a pour objectifs d’évaluer le potentiel d'une technique spécifique de caractérisation des propriétés d'écoulement des poudres : le rhéomètre à poudre FT4. L'objectif est de pouvoir mettre en place une analyse complète sur les avantages, les inconvénients et les limites d'utilisation des tests, l'impact de la cohésion des poudres et la répétabilité des mesures. Tout d'abord, des efforts sont faits pour explorer les différences entre la consolidation test de FT4 et le tap-tap. Les résultats indiquent que la consolidation test de FT4 a une bonne répétabilité, mais il peut sous-estimer la compressibilité des poudres. Cette méthode peut être optimisée en améliorant sa procédure d'initialisation pour donner des résultats cohérents en tant que le tap-tap. Deuxièmement, le cisaillement test de FT4 est comparé avec Schulze Ring Shear Tester et Evolution Powder Tester. Cette comparaison indique que le cisaillement test de FT4 peut sous-estimer la cohésion des poudres. Par conséquent, les dimensions des accessoires doivent être optimisées. Enfin, une nouvelle technique de caractérisation a été mise au point. Dans cette méthode, les poudres présentent des mouvements périodiques et la période correspondant peut être liée aux propriétés d'écoulement des poudres. Cette méthode a une très bonne capacité à identifier et à catégorier les propriétés d'écoulement de la poudre dans les conditions de faible contrainte. / This research has been dedicated to evaluate the reliability of the FT4 and to improve the current tests for a better and convenient powder characterization. Firstly, efforts are made to explore the differences between the compaction test provided by the FT4 and the traditional tapped density measurement. Results indicate that the FT4 compaction test has good repetability but it may underestimate powder compressibility. This method can be optimized by improving its initialization procedure to give consistent results as the tapped density measurement. Secondly, the shear tests provided by the FT4 are evaluated by comparing with the methodologies provided by Schulze Ring Shear Tester and Evolution Powder Tester. This comparison indicates that the FT4 shear cell test may underestimate powder strength, especially when a cohesive powder sample is measured, which may cause blockage when using the FT4 method to design a silo. To overcome this shortage, the dimensions of the shear accessories should be optimized. Most importantly, a new characterization technique has been developed. ln this method, powder materials present periodic motions and the cycle time of the periodic flow can be linked to the powder flow properties. This method has very good capability to identify and classify powder flow properties under low stress conditions.

This thesis focuses on particular materials and their flow properties. Handling of powder materials has an impact on technologic processes like storage, transport or dosage. In pharmacy flow properties are used for tabletting process of pills. For a correctly designed technologic process it is necessary to know the flow behaviour of powder materials. Measuring is the best way to study flow properties. The most commonly used instrument for measuring flowability are described in this thesis. Two different devices (Jenike shear device and Freeman FT4) were used to perform the experiments for the comparison of results. The tested materials were particular materials used in pharmacy. To further expand upon the research and to represent the importance of flowability, enclose to this work is a report regarding the examination of pyrolysis coke analyse from MOL Slovnaft.