Das totaldehnungskontrollierte Wechselverformungsverhalten unlegierter Stähle im normalisierten Zustand bei Raumtemperatur

In total strain-controlled tests without mean strain the cyclic deformation behaviour of unalloyed normalized steels with carbon contents 0,1 ≤ C ≤ 1,05 (wt.-%) is characterized by pronounced softening and slight hardening processes. With increasing carbon content the cyclic deformation curves are shifted to higher stress amplitudes. Cyclic stress strain curves of unalloyed steels determined in tests without mean load are independent of the testing procedure. With increasing carbon content the number of cycles for ε_a,e = ε_a,p (transition point) of strain-controlled SN-curves is shifted to smaller values.     

Zyklisches Kriechen des Vergütungsstahles 42 CrMo4 unter mittelspannungs-behafteter Zug-Druck-Wechselbeanspruchung bei Raumtemperatur

Kraftkontrollierte Zug-Druck-Wechselversuche an vergütetem Stahl 42 CrMo4. Ermittlung von Wechselverformungs- und Mitteldehnungskurven bei unterschiedlichen Kombinationen von Mittelspannung und Spannungsamplitude unter Raumtemperaturbedingungen. Konsequenzen für übliche Dauerfestigkeitsschaubilder.     

Residual Stress State of Brazed Ceramic/Metal Compounds, Determined by Analytical Methods and X-ray Residual Stress Measurements

The residual stress state of brazed ceramic/metal compounds is described by means of X-ray residual stress determinations and analytical calculations using a model of three elastic infinite plates. It is shown that the residual stress state of the soldered compound depends on the materials combination and on the geometrical conditions. The combination of X-ray residual stress measurements and analytical calculations allows decisions on whether the assumption of a linear elastic model, based on elementary bending theory, is valid for the particular compounds.     

The E3 architecture: enabling future cellular networks with cognitive and self‐x capabilities

Future mobile networks are expected to be complex heterogeneous systems. On the one hand this will enable users to take advantage of a number of different access technologies. On the other hand it will seriously affect network management procedures since more extensive operations and decisions will have to be dealt with. To tackle these challenges a number of new dynamic mechanisms need to be designed. It is imperative that certain network management tasks have to be performed without human intervention to reduce the OPEX costs and achieve faster responses in different events. To achieve this goal, the introduction of self‐x functionalities, combined with cognitive mechanisms and the ability to reconfigure network entities and terminals, is required. Moreover, the introduction of a new pilot channel needs to be considered to assist the terminals in selecting the most suitable radio access technology according to their requirements. We present the functional architecture of an evolved network that was designed in the context of the EU‐funded IP project ‘E³: End‐to‐End Efficiency’. This architecture aims to enhance existing procedures usually performed in traditional operation and maintenance systems (e.g. spectrum management, network planning, configuration actions). We explain the rationale of our design and provide specific examples to illustrate the role of the different functional entities and their interfaces. A considerable part of this architecture has recently been approved as a feasibility study by the ETSI Committee Reconfigurable Radio System. Copyright © 2010 John Wiley & Sons, Ltd.     

Einfluß positiver und negativer Mittelspannungen auf das zyklische Spannungs-Dehnungsverhalten von normalisiertem Ck 45

Influence of Positive and Negative Mean Stresses on the Cyclic Stress-Strain Behaviour of Normalized Steel SAE 1045 In technical parts cyclic loads are often superimposed by static load components. In such cases, mean stresses influence the cyclic deformation behaviour and produce cyclic creep effects. Single step push-pull fatigue tests were carried out with normalized specimens of the steel SAE 1045. Using cyclic deformation curves and cyclic creep curves, the influence of different mean stresses will be discussed.     

Zum Wechselverformungsverhalten von vergütetem 42 CrMo 4 bei zweistufiger Zug-Druck-Beanspruchung

Cyclic deformation behaviour of quenched and tempered 42 CrMo 4 (AISI 4140)at two-block push-pull-loading The behaviour of steels in the course of two- and multi-block cyclic loading has been investigated up to now almost exclusively regarding the fatigue life. According to this, only a few papers exist, dealing with the cyclic deformation behaviour at two- and multi-block-push-pull-loading. Therefore, in stress- and total strain-controlled experiments with a single change of the amplitude (two-block-experiments) and multiple changes between two blocks of different lengths and amplitudes (multi-block-experiments) the cyclic deformation processes have been investigated for the quenched and tempered steel grade 42 CrMo 4 (equivalent to AISI 4140). Using the data of stress- and strain-Wöhler-curves determined in usual fatigue tests, damages defined according to Miner's rule were adjoined to the blocks. The Miner-damages at failure observed in the two-black-experiments with changes from high to low amplitudes were smaller than one and at inverse changes of amplitudes larger that one. In contrast to this, in multi-block-experiments no universally valid correlations were observed between the Miner-damages at failure and the test-parameters applied. At all tests cyclic work-softening was observed as in single-step-experiments. However, work-softening processes at high amplitude loadings yield to much larger plastic strain amplitudes after changing to smaller amplitudes than in single-step tests. Contrarily, in multi-block-tests work-softening at higher amplitude loadings reduces with decreasing block-length and increasing portion of the blocks with the smaller amplitude. This is attributed to effects of static strain-ageing. Total-strain-controlled two-block cyclic deformation experiments yield to similar effects as in stress-controlled tests. However, the behaviour at high strain-amplitudes was influenced by distinct work-softening in the first cycles and by self-unloading due to the applied strain-control, which promotes quasi-stabilization-effects.