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Modelling of Fatigue Behaviour of Hard Multilayer Nanocoating System in Nanoimpact Test

The chapter presents the basis of the nanoimpact test and the idea of prediction of fracture occurrence, especially fatigue behaviour of nanoimpacted materials. The example of typical nanoimpact test is illustrated. The first part of the investigation is focused on the development of the finite element (FE) model, which is applied to identification of the material model of hard nanocoating in the multilayer system. Beyond this, the model is used to describe the friction contact between die and specimen, the shape of the die, the critical and required number of layers and dimension of investigated domain. Searching for the answers on formulated topics is realized using the inverse and the sensitivity analysis. Selected results indicating the problems with computing time in simulation of nanotests for the multilayer systems are presented in the chapter, as well. The FE model of the test with optimized parameters was developed and the results of chosen macrocrack criterion are shown. In the second part of the work the new approach to analysis of fracture phenomena is introduced as the fatigue criteria, which are used in simulation of nanoimpact test. The review of known fatigue criteria and analysis of fatigue behaviour are presented next and the selection of four of the criteria is justified. Finally, the results of simulations with the fatigue criteria implemented into the FE code for the analysed problem are shown and commented.

Identification of ductile fracture criterion on basis of experimental data

Abstract Development of a new fracture criterion in metal forming was the general objective of the paper. The emphasis was put on accounting for temperature and strain rate in a proposed criterion. Compression tests and strain induced crack opening (SICO) tests for the Inconel alloy were performed and applied for identification and validation of fracture criterion. Analysis of correlation and sensitivity analysis were applied to select the parameters, which are strongly influencing the conventional criteria. This part of the work showed that temperature and strain rate should be implemented into these criteria. Various criterion functions were analysed and that giving the minimum of the error in the identification was selected. The new criterion was validated by comparison its predictions with the SICO test results. Validation confirmed good qualitative predictive capability of the developed criterion. Further numerical tests were performed and probability of fracture during forging of blades process was predicted. L’objectif général de cet article consistait à développer un nouveau critère de rupture dans le travail des métaux. On a mis l’emphase sur la température et la vitesse de déformation pour le critère proposé. On a effectué et appliqué des essais de compression et ouverture de fissure induite par deformation (SICO) sur l’alliage Inconel, pour l’identification et la validation du critère de rupture. On a appliqué une analyse de corrélation et une analyse de sensitivité afin de choisir les paramètres, qui influencent fortement les critères conventionnels. Cette partie du travail a montré que l’on devrait implémenter la température et la vitesse de déformation dans ces critères. On a analysé diverses fonctions du critère et l’on a choisi celle qui produisait l’erreur minimale d’identification. On a validé le nouveau critère en comparant ses prédictions avec les résultats de l’essai SICO. La validation a confirmé une bonne capacité de prédiction qualitative du critère développé. On a effectué des essais numériques additionnels et l’on a prédit la probabilité de rupture lors du procédé de forgeage de pales.

Numerical Analysis of the Microstructure and Mechanical Properties Evolution during Equal Channel Angular Pressing

The development of the new technology for manufacturing of multi layer aluminium based materials for heat radiators is the subject of this work. Modern aluminium alloys can be specially processed in a controlled manner to obtain nano(mikro) structures. These ultra fine grained structures play a significant role because they provide a possibility to obtain final product that is characterized by elevated strength properties and, at the same time, good anticorrosion and soldering properties. A detailed understanding of these ultra fined structures using a combination of numerical modelling and experimental analysis is presented in this paper. Particular attention is put on implementation of the microstructure evolution model into the finite element software to simulate Equal Channel Angular Pressing (ECAP) process. Examples of the obtained results are presented and discussed.

Monitoring of WS-Based applications

The paper presents a Java-related monitoring platform for distributed applications which are oriented towards the use of Web Services (WS). We focus on the building a monitoring platform based on a well-defined interface (OMIS) between a monitoring system organized as middleware and tools that use the facilities provided by the monitoring middleware for WS-based applications. We aim at the observation and analysis of SOAP messages (data) exchanged with a Web Service (requests and responses). Our system is intended to monitor the characteristics of the remote call, especially: request time, transport time, cache access time, response time.