@article{Staat2000, author = {Staat, Manfred}, title = {Basis Reduction for the Shakedown Problem for Bounded Kinematic Hardening Material}, year = {2000}, abstract = {Limit and shakedown analysis are effective methods for assessing the load carrying capacity of a given structure. The elasto-plastic behavior of the structure subjected to loads varying in a given load domain is characterized by the shakedown load factor, defined as the maximum factor which satisfies the sufficient conditions stated in the corresponding static shakedown theorem. The finite element dicretization of the problem may lead to very large convex optimization. For the effective solution a basis reduction method has been developed that makes use of the special problem structure for perfectly plastic material. The paper proposes a modified basis reduction method for direct application to the two-surface plasticity model of bounded kinematic hardening material. The considered numerical examples show an enlargement of the load carrying capacity due to bounded hardening.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{Lohr2001, author = {Lohr, J{\"u}rgen}, title = {Content-Management f{\"u}r die Verteilung von Multimedia-Diensten}, year = {2001}, abstract = {In: Unterrichtsbl{\"a}tter / Deutsche Telekom AG. 54. 2001. 7. S. 410-420 (11 S. ) Angesichts der zunehmenden Globalisierung von Informationen und Informationsdiensten k{\"o}nnen Inhalte (Contents) f{\"u}r mehrere unterschiedliche Dienste genutzt und auf verschiedenen Endger{\"a}ten ausgegeben werden. Hier setzt ein Content-Management-System (CMS) an, welches sowohl f{\"u}r die Kunden als auch f{\"u}r die Anbieter der unterschiedlich distribuierten Dienste Synergien und somit Einsparpotenziale bietet. Dar{\"u}ber hinaus werden f{\"u}r die Anbieter dieser Dienste durch die allgemeine Definition von Leistungstools und die Definition von Wertsch{\"o}pfungsketten k{\"u}nftige Produktentwicklungen vereinheitlicht und optimiert werden. Mit der Entwicklung und Vertriebsfreigabe immer weiterer Informationsdienste, die von verschiedenen Dienste-Providern betrieben werden, ist der Bedarf an einer Koordinierung der Entwicklungen und Investitionen im Bereich der Content-Akquisition und des Content-Management (CM) bedeutend angestiegen. Neben Akquisition, lizenzrechtlichen Fragen und Verwaltung des im Rahmen von Diensten angebotenen Content r{\"u}cken vor allem auch Fragen der Gestaltung von Content-Management-Plattformen (CMP) immer st{\"a}rker in den Blickpunkt. Der Beitrag stellt die globalen Ergebnisse dar, die in einem Forschungs- und Entwicklungsauftrag des Zentralbereichs Innovationsmanagement der Deutschen Telekom zu diesem Thema ermittelt wurden. Es werden die Kernmodule f{\"u}r eine Content- Management-Plattform beschrieben, die die Anforderungen an die Bereitstellung vielf{\"a}ltiger Content-Angebote erf{\"u}llt. Die folgenden Themen werden behandelt: + Begriffsbestimmung, + Content- und Dienste-Portfolio, + Standard Content-Prozess, + synergetische Content-Plattform (sCP), + Modelle der sCP, + Aspekte beim Betrieb und + Nutzen eines Content-Management.}, subject = {Content Management}, language = {de} } @article{Staat2001, author = {Staat, Manfred}, title = {Cyclic plastic deformation tests to verify FEM-based shakedown analyses}, year = {2001}, abstract = {Fatigue analyses are conducted with the aim of verifying that thermal ratcheting is limited. To this end it is important to make a clear distintion between the shakedown range and the ratcheting range (continuing deformation). As part of an EU-supported research project, experiments were carried out using a 4-bar model. The experiment comprised a water-cooled internal tube, and three insulated heatable outer test bars. The system was subjected to alternating axial forces, superimposed with alternating temperatures at the outer bars. The test parameters were partly selected on the basis of previous shakedown analyses. During the test, temperatures and strains were measured as a function of time. The loads and the resulting stresses were confirmed on an ongoing basis during performance of the test, and after it. Different material models were applied for this incremental elasto-plastic analysis using the ANSYS program. The results of the simulation are used to verify the FEM-based shakedown analysis.}, subject = {Materialerm{\"u}dung}, language = {en} } @article{Staat2001, author = {Staat, Manfred}, title = {LISA - a European project for FEM-based limit and shakedown analysis}, year = {2001}, abstract = {The load-carrying capacity or the safety against plastic limit states are the central questions in the design of structures and passive components in the apparatus engineering. A precise answer is most simply given by limit and shakedown analysis. These methods can be based on static and kinematic theorems for lower and upper bound analysis. Both may be formulated as optimization problems for finite element discretizations of structures. The problems of large-scale analysis and the extension towards realistic material modelling will be solved in a European research project. Limit and shakedown analyses are briefly demonstrated with illustrative examples.}, subject = {Einspielen }, language = {en} } @article{PicardBrillCasseletal.2002, author = {Picard, Antoni and Brill, Manfred and Cassel, Detlev and Jentsch, Andreas and Rollwa, Markus and K{\"a}mper, Klaus-Peter and Merten, Sabine}, title = {Neue Medien f{\"u}r die praktische MST-Ausbildung}, organization = {FH-Kaiserslautern}, year = {2002}, abstract = {Im Studiengang Mikrosystemtechnik des Fachhochschulstandortes Zweibr{\"u}cken werden zwei neue moderne Anlagen f{\"u}r die Herstellung von mikrotechnischen Komponenten in Betrieb genommen: Ein Oxidationsofen f{\"u}r Herstellung d{\"u}nner Oxidschichten auf Silizium-Einkristallen und eine Belichtungsapparatur f{\"u}r die Fotolithografie - das Besondere an diesen Anlagen: Sie existieren nur virtuell, d.h. als Animationen in einer Computerwelt.}, subject = {Mikrosystemtechnik}, language = {de} } @article{KernKrichel2003, author = {Kern, Alexander and Krichel, Frank}, title = {{\"U}berlegungen zum Blitzschutzkonzept f{\"u}r regenerative Energieanlagen}, year = {2003}, abstract = {Dem Blitzschutz von Anlagen der regenerativen Energien kommt in Zukunft eine steigende Bedeutung zu. Dabei ist es notwendig zu ber{\"u}cksichtigen, dass die Schutzmaßnahmen technisch/wirtschaftlich ausgewogen sind. Erbauer, Besitzer oder Benutzer von netzautarken Hybridanlagen haben zu entscheiden, ob die Anlage einen Schutz braucht oder nicht. Um diese Entscheidung zu f{\"a}llen, ist eine Risikoanalyse als erster Schritt sinnvoll. Diese muss dabei die f{\"u}r die Hybridanlage relevanten Schadenarten und spezifischen Parameter, Werte und Randbedingungen mit einbeziehen. Dazu ist die Hilfe eines Blitzschutzexperten sehr hilfreich.}, subject = {Alternative Energiequelle}, language = {de} } @article{Kern2003, author = {Kern, Alexander}, title = {Risikomanagement f{\"u}r den Blitzschutz - Absch{\"a}tzung des Blitzschadensrisikos nach der neuen Vornorm VDE V 0185 Teil 2 : 2002}, year = {2003}, abstract = {Ein vorausschauendes Risikomanagement beinhaltet, Risiken zu kalkulieren. Es liefert Entscheidungsgrundlagen, um diese Risiken zu begrenzen und es macht transparent,welche Risiken sinnvoll {\"u}ber Versicherungen abgedeckt werden sollten. Bei Unternehmen, die mit umfangreichen elektronischenEinrichtungen produzieren oder Dienstleistungen erbringen (und das sind heutzutage wohl die meisten), muss auch das Risiko durch Blitzeinwirkungen besondere Ber{\"u}cksichtigung finden. Dabei ist zu beachten, dass der Schaden aufgrund der Nichtverf{\"u}gbarkeit der elektronischen Einrichtungen und damit derProduktion bzw. der Dienstleistung und ggf. der Verlust von Daten den Hardwareschaden an der betroffenen Anlage oft bei weitem {\"u}bersteigt.}, language = {de} } @article{BaroudWuBohneretal.2003, author = {Baroud, G. and Wu, J.Z. and Bohner, M and Sponagel, Stefan and Steffen, T.}, title = {How to determine the permeability for cement infiltration into osteoporotic cancellous bone}, series = {Medical Engineering \& Physics. 25 (2003), H. 4}, journal = {Medical Engineering \& Physics. 25 (2003), H. 4}, issn = {1350-4533}, pages = {283 -- 288}, year = {2003}, abstract = {Cement augmentation is an emerging surgical procedure in which bone cement is used to infiltrate and reinforce osteoporotic vertebrae. Although this infiltration procedure has been widely applied, it is performed empirically and little is known about the flow characteristics of cement during the injection process. We present a theoretical and experimental approach to investigate the intertrabecular bone permeability during the infiltration procedure. The cement permeability was considered to be dependent on time, bone porosity, and cement viscosity in our analysis. In order to determine the time-dependent permeability, ten cancellous bone cores were harvested from osteoporotic vertebrae, infiltrated with acrylic cement at a constant flow rate, and the pressure drop across the cores during the infiltration was measured. The viscosity dependence of the permeability was determined based on published experimental data. The theoretical model for the permeability as a function of bone porosity and time was then fit to the testing data. Our findings suggest that the intertrabecular bone permeability depends strongly on time. For instance, the initial permeability (60.89 mm4/N.s) reduced to approximately 63\% of its original value within 18 seconds. This study is the first to analyze cement flow through osteoporotic bone. The theoretical and experimental models provided in this paper are generic. Thus, they can be used to systematically study and optimize the infiltration process for clinical practice.}, subject = {Osteoporose}, language = {en} } @article{KaemperPicardBrilletal.2003, author = {K{\"a}mper, Klaus-Peter and Picard, Antoni and Brill, Manfred and Cassel, Detlev and Jentsch, Andreas and Merten, Sabine and Rollwa, Markus}, title = {The Virtual Clean Room - a new tool in teaching MST process technologies}, year = {2003}, abstract = {The Virtual Clean Room - a new tool in teaching MST process technologies University education in high-technology fields like MST is not complete without intensive laboratory sessions. Students cannot fully grasp the complexity and the special problems related to the manufacturing of microsystems without a thorough hands-on experience in a MST clean room.}, subject = {Virtuelle Maschine}, language = {en} } @article{Staat2003, author = {Staat, Manfred}, title = {Shakedown and ratchetting under tension-torsion loadings: analysis and experiments}, year = {2003}, abstract = {Structural design analyses are conducted with the aim of verifying the exclusion of ratchetting. To this end it is important to make a clear distinction between the shakedown range and the ratchetting range. The performed experiment comprised a hollow tension specimen which was subjected to alternating axial forces, superimposed with constant moments. First, a series of uniaxial tests has been carried out in order to calibrate a bounded kinematic hardening rule. The load parameters have been selected on the basis of previous shakedown analyses with the PERMAS code using a kinematic hardening material model. It is shown that this shakedown analysis gives reasonable agreement between the experimental and the numerical results. A linear and a nonlinear kinematic hardening model of two-surface plasticity are compared in material shakedown analysis.}, subject = {Einspielen }, language = {en} }