@article{Staat2004, author = {Staat, Manfred}, title = {Plastic collapse analysis of longitudinally flawed pipes and vessels}, year = {2004}, abstract = {Improved collapse loads of thick-walled, crack containing pipes and vessels are suggested. Very deep cracks have a residual strength which is better modelled by a global limit load. In all burst tests, the ductility of pressure vessel steels was sufficiently high whereby the burst pressure could be predicted by limit analysis with no need to apply fracture mechanics. The relative prognosis error increases however, for long and deep defects due to uncertainties of geometry and strength data.}, subject = {Druckbeh{\"a}lter}, language = {en} } @article{SchoeningSchubertKloocketal.2002, author = {Sch{\"o}ning, Michael Josef and Schubert, J and Kloock, Joachim P. and Zander, W. and Mourzina, Y. G. and Legin, A. and Vlasov, Y. G. and L{\"u}th, H.}, title = {Innovative thin film techniques for microfabricating electrochemical sensors}, series = {Lecture Notes of the ICB Seminars}, journal = {Lecture Notes of the ICB Seminars}, publisher = {MCB}, address = {Warsaw}, pages = {55 -- 66}, year = {2002}, language = {en} } @article{Schoening2003, author = {Sch{\"o}ning, Michael Josef}, title = {Silicon-based biochemical sensors}, series = {CNI - The Center of Nanoelectronic Systems for Information Technology}, journal = {CNI - The Center of Nanoelectronic Systems for Information Technology}, publisher = {Foschungszentrum J{\"u}lich}, pages = {165 -- 170}, year = {2003}, language = {en} } @article{SchoeningLueth2002, author = {Sch{\"o}ning, Michael Josef and L{\"u}th, H.}, title = {Microfabricated semiconductor structures - Advances in (bio-)chemical sensing}, series = {Coupling of biological and electronic systems : proceedings of the 2nd Caesarium, Bonn, November 1 - 3, 2000 / Karl-Heinz Hoffmann, ed.}, journal = {Coupling of biological and electronic systems : proceedings of the 2nd Caesarium, Bonn, November 1 - 3, 2000 / Karl-Heinz Hoffmann, ed.}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {3-540-43699-5}, pages = {79 -- 92}, year = {2002}, language = {en} } @article{SchoeningSchubertKloocketal.2001, author = {Sch{\"o}ning, Michael Josef and Schubert, Joachim P. and Kloock, Joachim P. and Zander, W. and Mourzina, Y. G. and Legin, A. and Vlasov, Y. G. and L{\"u}th, H.}, title = {Innovative thin film techniques for microfabricating electrochemical sensors}, series = {Biocybernetics and Biomedical Engineering. 21 (2001), H. 4}, journal = {Biocybernetics and Biomedical Engineering. 21 (2001), H. 4}, isbn = {0208-5216}, pages = {107 -- 119}, year = {2001}, language = {en} } @article{SchrothWeissbeckerSchuetzetal.2002, author = {Schroth, P. and Weißbecker, B. and Sch{\"u}tz, S. and Ecken, H. and Yoshinobu, T. and L{\"u}th, H. and Sch{\"o}ning, Michael Josef}, title = {Bioelectronic signal processing - intact chemoreceptors coupled to field-effect devices}, series = {Lecture Notes of the ICB Seminars}, journal = {Lecture Notes of the ICB Seminars}, publisher = {MCB}, address = {Warsaw}, pages = {28 -- 42}, year = {2002}, language = {en} } @article{SchrothWeissbeckerSchuetzetal.2001, author = {Schroth, P. and Weißbecker, B. and Sch{\"u}tz, S. and Ecken, H. and Yoshinobu, T. and L{\"u}th, H. and Sch{\"o}ning, Michael Josef}, title = {Bioelectronic signal processing - intact chemoreceptors coupled to field-effect devices}, series = {Biocybernetics and Biomedical Engineering. 21 (2001), H. 3}, journal = {Biocybernetics and Biomedical Engineering. 21 (2001), H. 3}, isbn = {0208-5216}, pages = {27 -- 42}, year = {2001}, language = {en} } @article{Schoening2002, author = {Sch{\"o}ning, Michael Josef}, title = {Novel approaches to design siliconbased field-effect sensors}, series = {Electrochemical Microsystem Technologies, New Trends in Electrochemistry Vol. 2}, journal = {Electrochemical Microsystem Technologies, New Trends in Electrochemistry Vol. 2}, publisher = {Taylor \& Francis}, address = {London New York}, pages = {384 -- 408}, year = {2002}, language = {en} } @article{SchoeningLueth2001, author = {Sch{\"o}ning, Michael Josef and L{\"u}th, H.}, title = {Novel concepts for silicon-based biosensors}, series = {Physica Status Solidi (A) (2001)}, journal = {Physica Status Solidi (A) (2001)}, isbn = {0031-8965}, pages = {65 -- 77}, year = {2001}, language = {en} } @article{Staat2000, author = {Staat, Manfred}, title = {Direct FEM Limit and Shakedown Analysis with Uncertain Data}, year = {2000}, abstract = {The structural reliability with respect to plastic collapse or to inadaptation is formulated on the basis of the lower bound limit and shakedown theorems. A direct definition of the limit state function is achieved which permits the use of the highly effective first order reliability methods (FORM) is achieved. The theorems are implemented into a general purpose FEM program in a way capable of large-scale analysis. The limit state function and its gradient are obtained from a mathematical optimization problem. This direct approach reduces considerably the necessary knowledge of uncertain technological input data, the computing time, and the numerical error, leading to highly effective and precise reliability analyses.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{VuStaat2004, author = {Vu, Duc-Khoi and Staat, Manfred}, title = {An algorithm for shakedown analysis of structure with temperature dependent yield stress}, year = {2004}, abstract = {This work is an attempt to answer the question: How to use convex programming in shakedown analysis of structures made of materials with temperature-dependent properties. Based on recently established shakedown theorems and formulations, a dual relationship between upper and lower bounds of the shakedown limit load is found, an algorithmfor shakedown analysis is proposed. While the original problem is neither convex nor concave, the algorithm presented here has the advantage of employing convex programming tools.}, subject = {Einspielen }, language = {en} } @article{KuehnHaugnerStaatetal.2004, author = {K{\"u}hn, Raoul-Roman and Haugner, Werner and Staat, Manfred and Sponagel, Stefan}, title = {A Two Phase Mixture Model based on Bone Observation}, year = {2004}, abstract = {An optimization method is developed to describe the mechanical behaviour of the human cancellous bone. The method is based on a mixture theory. A careful observation of the behaviour of the bone material leads to the hypothesis that the bone density is controlled by the principal stress trajectories (Wolff's law). The basic idea of the developed method is the coupling of a scalar value via an eigenvalue problem to the principal stress trajectories. On the one hand this theory will permit a prediction of the reaction of the biological bone structure after the implantation of a prosthesis, on the other hand it may be useful in engineering optimization problems. An analytical example shows its efficiency.}, subject = {Knochen}, language = {en} } @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{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{Staat2005, author = {Staat, Manfred}, title = {Local and global collapse pressure of longitudinally flawed pipes and cylindrical vessels}, year = {2005}, abstract = {Limit loads can be calculated with the finite element method (FEM) for any component, defect geometry, and loading. FEM suggests that published long crack limit formulae for axial defects under-estimate the burst pressure for internal surface defects in thick pipes while limit loads are not conservative for deep cracks and for pressure loaded crack-faces. Very deep cracks have a residual strength, which is modelled by a global collapse load. These observations are combined to derive new analytical local and global collapse loads. The global collapse loads are close to FEM limit analyses for all crack dimensions.}, subject = {Finite-Elemente-Methode}, language = {en} } @article{Staat2005, author = {Staat, Manfred}, title = {Direct finite element route for design-by-analysis of pressure components}, year = {2005}, abstract = {In the new European standard for unfired pressure vessels, EN 13445-3, there are two approaches for carrying out a Design-by-Analysis that cover both the stress categorization method (Annex C) and the direct route method (Annex B) for a check against global plastic deformation and against progressive plastic deformation. This paper presents the direct route in the language of limit and shakedown analysis. This approach leads to an optimization problem. Its solution with Finite Element Analysis is demonstrated for mechanical and thermal actions. One observation from the examples is that the so-called 3f (3Sm) criterion fails to be a reliable check against progressive plastic deformation. Precise conditions are given, which greatly restrict the applicability of the 3f criterion.}, subject = {Einspielen }, 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} } @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{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{BassamArtmannHescheleretal.2011, author = {Bassam, Rasha and Artmann, Gerhard and Hescheler, J{\"u}rgen and Graef, T. and Temiz Artmann, Ayseg{\"u}l and Porst, Dariusz and Linder, Peter and Kayser, Peter and Arinkin, Vladimir and Gossmann, Matthias and Digel, Ilya}, title = {Alterations in human hemoglobin structure related to red blood cell storage}, year = {2011}, abstract = {The importance of the availability of stored blood or blood cells, respectively, for urgent transfusion cannot be overestimated. Nowadays, blood storage becomes even more important since blood products are used for epidemiological studies, bio-technical research or banked for transfusion purposes. Thus blood samples must not only be processed, stored, and shipped to preserve their efficacy and safety, but also all parameters of storage must be recorded and reported for Quality Assurance. Therefore, blood banks and clinical research facilities are seeking more accurate, automated means for blood storage and blood processing.}, subject = {H{\"a}moglobin}, language = {en} }