Analytical and experimental investigations of the vibrations of a hollow blade model of turbines

The practice of using air-cooled blades for the increased efficiency of turbine stage is a recent feature with advanced aero-engines. The objective of the present paper is to describe the results of numerical and experimental investigation of the dynamical behaviour of hollow cross-sectioned blades. The analytical method consists in modelling the blades by means of a finite-element method to determine the natural frequencies and normal modes of a hollow cross-sectioned blade model. Numerical results are compared with experimental values obtained from holographic tests.     

Helmut Bettman verstorben

Ohne Zusammenfassung     

Sliding friction behaviour of polymer-polymer material combinations

The intermolecular bonding energies of polymeric materials can be employed in the evaluation of sliding under conditions determined predominantly by adhesion. The effect at the interface of these energies can be evaluated by reference to the surface energy and to its polar and dispersion-related components. Wetting angle measurements were used to determine the work of adhesion for a group of polymer-polymer material combinations. An exponential relationship exists between the work of adhesion and the coefficients of friction of these combinations, these coefficients of friction being determined primarily by adhesion.     

Prozeßsystemtechnik — Gedanken zu Notwendigkeit und Inhalt einer akademischen Lehre

Process System Engineering. Thoughts on the need for and curriculum of an academic course of instruction . The raw material, energy, and environmental situation, international competition, and the decline in product innovation are increasingly casting doubts on conventional processes and their realization. Hence, in the future-training of chemical engineers a reasonable amount of time should be devoted to the study of system facets, i. e. to thinking and acting in complex systems of interrelationships. Under the general leading ?Process System Engineering”? those activities are discussed which are relevant to the design and planning of chemical engineering systems (process synthesis) and the mathematical analysis of a given system (process analysis). Process synthesis is the creative facet of project planning involving several methodologies. Process analysis embraces steady-state and non-steady state mass- and energy-balancing and the mathematical evaluation of various process alternatives on the basis of operating costs and investment as well as the simulation of operational behaviour and optimization of process configurations using mathematical models. The following article discusses a selection of points which should play an important part in the teaching of process synthesis and process analysis and considers some examples by way of illustration.     

Delaminationsbruch von warmgewalztem,mikrolegiertem Baustahl

Beschreibung der Brucherscheinung. Gefügeuntersuchung an einem mikrolegierten Baustahl mit rd. 0,05% Nb und 0,1% V nach unterschiedlicher thermomechanischer Behandlung zur Ermittlung der Bruchursachen. Deutung der Bruchursachen durch Ausscheidungsvorgänge bei der thermomechanischen Behandlung.