Niedrig-Lastwechsel-Ermüdung - Ein Kritischer Überblick

Low Cycle Fatigue - A Critical Survey After describing and defining the field of Low Cycle Fatigue, the most important life-time prediction methods are presented and their applications discussed. It is assumed that lifetime to crack initiation is significantly influenced by the local cyclic plastic deformation in the critical area of the component. – At the present time no reliable life-time prediction is possible for service load sequences (variable amplitudes, hold-times). In many practical cases however, the calculation can be based on simplified load sequences.     

Ermüdungslebensdauerbewertung von Warmumformwerkzeugen – Ein Überblick über den Stand der Forschung und Anwendung

Hot work tools are subjected to complex thermal and mechanical loads during hot forming processes. Locally, the stresses can exceed the material's yield strength in highly loaded areas. During mass production, this leads to cyclic plastic deformations and thermomechanical fatigue of the tools, which can be a major lifetime limiting factor. However, established concepts for thermomechanical fatigue life assessment of hot work tools do not exist, since this aspect first reached attention in the last years with the needs for higher resource and energy efficiency as well as optimized manufacturing processes (e. g. in the frame of Industrie 4.0). Hence, in this paper, the contemporary industrially used concepts for dimensioning hot forming tools regarding the tooling fatigue life are presented. Furthermore an overview of existing plasticity and lifetime models is given. The models are divided in phenomenological and mechanism based models. The review shows that further research is essential in this field.     

Modifikation von Titan durch Ionenimplantation-Ein Überblick

Modification of Titanium by Ion Implantation-A Review This paper reviews investigations concerning the effect of ion implantation on the properties of titanium alloys. The correlations between the process parameters and the phase formation in implanted layers, the wear and strength properties as well as the corrosion and oxidation behaviour are described. The application for joint prostheses is mentioned.     

Schadensakkumulationshypothesen zur Lebensdauervorhersage bei schwingender Beanspruchung. Teil 2. – Ein kritischer Überblick—

Cumulative Damage Theories for the Prediction of Fatigue Life . Most fatigue data are determined in constant stress amplitude tests. Therefore they are not applicable directly for the prediction of fatigue life under service loads: A “cumulative damage theory” is necessary. For about 350 program test series (blocked 8 stress level tests) the cumulative damage sum Σ n_i/N_i at failure is calculated. The mean value of this ratio is near 1,0 and thus agrees with Miner's rule; however the scatter is extremely high. Tests in bending give significantly lower damage sums than tests under axial loads. Furthermore about 130 random and flight by flight tests are analysed. Next, modified linear damage theories are discussed and it shows that only theories which take residual stresses into account will improve the accuracy. A relative fatigue life estimation is proposed, where one test under service conditions is the basis and Miner's rule is used as a transfer function.     

Schadensakkumulationshypothesen zur Lebensdauervorhersage bei schwingender Beanspruchung. Teil 1. – Ein kritischer Überblick—

Cumulative Damage Theories for the Prediction of Fatigue Life . Most fatigue data are determined in constant stress amplitude tests. Therefore they are not applicable directly for the prediction of fatigue life under service loads: A ?cumulative damage theory”? is necessary. For about 350 program test series (blocked 8 stress level tests) the cumulative damage sum Σ n_i/N_i at failure is calculated. The mean value of this ratio is near 1,0 and thus agrees with Miner's rule; however the scatter is extremely high. Tests in bending give significantly lower damage sums than tests under axial loads. Furthermore about 130 random and flight by flight tests are analysed. Next, modified linear damage theories are discussed and it shows that only theories which take residual stresses into account will improve the accuracy. A relative fatigue life estimation is proposed, where one test under service conditions is the basis and Miner's rule is used as a transfer function.     

Plasmapolymerisation — Ein Verfahren für viele Anwendungen

Plasma Polymerization is a new technology that allows to produce thin coatings with manifold properties. It enables especially the coating of plastics because of its low thermal heating effect. The technology will be described in this paper by explanation of microwave Plasma Polymerization. Plasma, process and equipment are described. A survey of some applications shows, how many different technical domains are affected. Details concerning industrial use, like coated area, process time, and economy, are discussed.     

OR-Modelle zur Planung flexibler Fertigungssysteme Ein Überblick

Zusammenfassung In diesem Beitrag wird ein Überblic über die Probleme vermittelt, die sich bei der Konfiguration und dem Betrieb eines flexiblen Fertigungssystems stellen. Die zur Behandlung der wichtigsten Problemtypen verfügbaren Modellierungsansätze werden systematisch beschrieben und auf ihren möglichen Einsatz zur Entscheidungsunterstützung für die betriebliche Praxis hin untersucht.