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Brinckmann S.,Max Planck Institute Fur Eisenforschung | Volker B.,KAI Kompetenzzentrum Automobil und Industrie Elektronik GmbH | Dehm G.,Max Planck Institute Fur Eisenforschung
International Journal of Fracture | Year: 2014

Four-point bending experiments are conceptually the method of choice when investigating the delamination strength of multi-layered components, which are of particular interest for semiconductor applications. However, experimental studies have shown that the crack continues as mode-I crack in most cases while delamination is rarely observed, thus making the four-point bending method useless. This study uses the finite element method with cohesive zones to study crack propagation and the likelihood of turning the initial mode-I crack into a delamination crack in a multi-layered structure. We close with a conclusion which can help to increase the delamination probability and thereby help to determine the delamination strengths of layered structures. © 2014, Springer Science+Business Media Dordrecht. Source


Dastmalchi B.,Johannes Kepler University | Kheradmand R.,University of Tabriz | Kheradmand R.,Institute for Research in Fundamental Sciences | Hamidipour A.,Johannes Kepler University | And 4 more authors.
Progress In Electromagnetics Research B | Year: 2010

Recently, we have introduced a numerical method for calculating local dispersion of arbitrary shaped optical waveguides, which is based on the Finite-Difference Time-domain and filter diagonalization technique. In this paper we present a study of photonic crystal waveguides at interfaces and double hetero-structure waveguides. We have studied the waveguide stretching effect, which is the change in lattice constant of photonic crystals along waveguiding direction. Hybrid modes at photonic crystal heterostructure interfaces are observed, which are the results of superposition of existing modes in adjacent waveguides. The dispersion at the interfaces of a double hetero-structure waveguide tends to the dispersion of outer waveguides. The effective area still holding the dispersion of the middle waveguide is shorter than the geometrical length of the middle waveguide. The results of this study present a clear picture of dispersion at interfaces and the transmission in photonic crystal hetero-structures. Source


Best J.P.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Zechner J.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Zechner J.,KAI Kompetenzzentrum Automobil und Industrie Elektronik GmbH | Shorubalko I.,Empa - Swiss Federal Laboratories for Materials Science and Technology | And 4 more authors.
Scripta Materialia | Year: 2016

While small-scale fracture toughness measurements provide an extremely useful material parameter, notch preparation and ion-beam damage continue to be contentious issues. Herein we utilize a conventional gallium source for notching ceramic cantilevers, and compare against notches fabricated using xenon and helium ions from commercial focused ion microscopes. This is the first time ions other than gallium have been used for notches in such measurements. We observe some statistical dependence of the measured toughness on the utilized notching ion, bringing into question the influence of ion-material interactions in creating residual stresses or embrittlement in the small volumes around the notch root. © 2015 Elsevier Ltd. All rights reserved. Source


Krivec S.,KAI Kompetenzzentrum Automobil und Industrie Elektronik GmbH | Krivec S.,Vienna University of Technology | Detzel T.,Infineon Technologies | Buchmayr M.,Infineon Technologies | Hutter H.,Vienna University of Technology
Applied Surface Science | Year: 2010

The detection of Na in insulating samples by means of time of flight-secondary ion mass spectrometry (ToF-SIMS) depth profiling has always been a challenge. In particular the use of O2 + as sputter species causes a severe artifact in the Na depth distribution due to Na migration under the influence of an internal electrical filed. In this paper we address the influence of the sample temperature on this artifact. It is shown that the transport of Na is a dynamic process in concordance with the proceeding sputter front. Low temperatures mitigated the migration process by reducing the Na mobility in the target. In the course of this work two sample types have been investigated: (i) A Na doped PMMA layer, deposited on a thin SiO 2 film. Here, the incorporation behavior of Na into SiO2 during depth profiling is demonstrated. (ii) Na implanted into a thin SiO 2 film. By this sample type the migration behavior could be examined when defects, originating from the implantation process, are present in the SiO2 target. In addition, we propose an approach for the evaluation of an implanted Na profile, which is unaffected by the migration process. © 2010 Elsevier B.V. All rights reserved. Source


Kolednik O.,Austrian Academy of Sciences | Zechner J.,Austrian Academy of Sciences | Zechner J.,Materials Center Leoben Forschung | Zechner J.,KAI Kompetenzzentrum Automobil und Industrie Elektronik GmbH | Predan J.,University of Maribor
Scripta Materialia | Year: 2016

Retardation of fatigue crack growth rate due to the introduction of thin, compliant and/or soft interlayers is investigated. The mechanism is the reduction of the crack driving force in the interlayer. Fatigue tests are conducted on composites made of high-strength aluminum alloy as matrix and technically pure aluminum or adhesive as interlayer material. The adhesive interlayer causes an increase in fatigue life by a factor 20 or more, whereas the aluminum interlayer yields only a moderate improvement. Numerical simulations based on the configurational force concept are utilized for understanding. The results show new possibilities for the design of fatigue-resistant materials. © 2015 Elsevier Ltd. All rights reserved. Source

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