Article
Refine
Year of publication
Institute
- Fachbereich Medizintechnik und Technomathematik (45) (remove)
Has Fulltext
- yes (45) (remove)
Language
- English (45) (remove)
Document Type
- Article (45) (remove)
Keywords
- Einspielen <Werkstoff> (7)
- FEM (4)
- Finite-Elemente-Methode (4)
- Capacitive field-effect sensor (2)
- Einspielanalyse (2)
- Label-free detection (2)
- Shakedown analysis (2)
- Traglastanalyse (2)
- biosensors (2)
- capacitive field-effect sensors (2)
- shakedown (2)
- shakedown analysis (2)
- Air purification (1)
- Alternating plasticity (1)
- Analysis (1)
- Analytischer Zulaessigkeitsnachweis (1)
- Architectural design (1)
- Axialbelastung (1)
- Axially cracked pipe (1)
- Bacterial cellulose (1)
- Basis Reduktion (1)
- Basis reduction (1)
- Bauingenieurwesen (1)
- Bicharakteristikenverfahren (1)
- Bioabsorbable (1)
- Bioreaktor (1)
- Blutzellenlagerung (1)
- Bone quality and biomechanics (1)
- CAD (1)
- Carbon sources (1)
- Cellulose nanostructure (1)
- Cement infiltration (1)
- Clusterion (1)
- Convex optimization (1)
- Cost-effectiveness (1)
- Culture media (1)
- Deformation (1)
- Design-by-analysis (1)
- Druckbeanspruchung (1)
- Druckbehälter (1)
- Druckbelastung (1)
- Druckgeräte (1)
- E. coli detection (1)
- ELISA (1)
- Einspiel-Analyse (1)
- Einspiel-Kriterium (1)
- Einspielen (1)
- Elastizität (1)
- Enterprise information systems (1)
- Environmental impact (1)
- Enzyme-linked immunosorbent assay (1)
- Epithel (1)
- Experiment (1)
- Fault approximation (1)
- Fault detection (1)
- Fehlerstellen (1)
- Fibroblast (1)
- Fließgrenze (1)
- Geriatric (1)
- German (1)
- Global and local collapse (1)
- Gold nanoparticles (1)
- Grenzwertberechnung (1)
- Harnleiter (1)
- Hemoglobin structure (1)
- Hip fractures (1)
- Hämoglobin (1)
- Hämoglobinstruktur (1)
- Information extraction (1)
- Inverse scattering problem (1)
- Knochen (1)
- Knochenbildung (1)
- Knochenchirugie (1)
- Knochendichte (1)
- Kohlenstofffaser (1)
- Limit analysis (1)
- Lipopolysaccharide (1)
- Luftreiniger (1)
- MCDA (1)
- Master stamp (1)
- Materialermüdung (1)
- Medusomyces gisevi (1)
- Model-driven software engineering (1)
- Multicell (1)
- Multiplexing (1)
- Organkultur (1)
- Osteoporose (1)
- Osteoporosis (1)
- Permeability (1)
- Permeabilität (1)
- Peroxidase (1)
- Pflanzenphysiologie (1)
- Pflanzenscanner (1)
- Pflanzenstress (1)
- Photolithographic mimics (1)
- Plant virus (1)
- Plasmacluster ion technology (1)
- Plastizität (1)
- Polylactide acid (1)
- Pressure loaded crack-face (1)
- Prevention (1)
- Progressive plastic deformation (1)
- Prophylaxis (1)
- Quartz crystal microbalance (1)
- Ratchetting (1)
- Raumluft (1)
- Red blood cell storage (1)
- Resistive temperature detector (1)
- Rohr (1)
- Rohrbruch (1)
- Schwammknochen (1)
- Shakedown (1)
- Shakedown criterion (1)
- Silk fibroin (1)
- Skeletal muscle (1)
- Small Aral Sea (1)
- Software and systems modeling (1)
- Stahl (1)
- Strukturanalyse (1)
- Surface imprinted polymer (1)
- Temperaturabhängigkeit (1)
- Tendons (1)
- Tissue Engineering (1)
- Tobacco mosaic virus (TMV) (1)
- Traglast (1)
- Ultrasound (1)
- Vertebroplastie (1)
- Vertebroplasty (1)
- Viscous flow (1)
- Viskose Strömung (1)
- Viskosität (1)
- Wolff's Law (1)
- Wolffsches Gesetz (1)
- Wundheilung (1)
- Zeta potential (1)
- Zug-Druck Belastung (1)
- acetoin (1)
- acetoin reductase (1)
- alcoholic beverages (1)
- alternierend Verformbarkeit (1)
- amperometric biosensors (1)
- aromatic amines (1)
- atomic layer deposition (1)
- bicharacteristics (1)
- bioburdens (1)
- biocompatible (1)
- biocompatible materials (1)
- biodegradabl (1)
- biodegradable electronic devices (1)
- bone density (1)
- bone structure (1)
- burst pressure (1)
- burst tests (1)
- cancellous bone (1)
- capacitive electrolyte–insulator–semiconductor sensors (1)
- carbon electrodes (1)
- carbonized rice husk (1)
- civil engineering (1)
- direct method (1)
- ecological structure (1)
- elastic solids (1)
- encapsulation materials (1)
- enzymatic biosensor (1)
- epithelization (1)
- fatigue analyses (1)
- fibroin (1)
- flaw (1)
- fortschreitende plastische Deformation (1)
- glucose (1)
- graphene oxide (1)
- human dermal fibroblasts (1)
- konvexe Optimierung (1)
- large language models (1)
- layer-by-layer technique (1)
- limit analysis (1)
- limit load (1)
- lipopolysaccharides (1)
- load limit (1)
- metagenomics (1)
- microbial diversity (1)
- nanomaterials (1)
- nanostructured carbonized plant parts (1)
- nanostrukturierte carbonisierte Pflanzenteile (1)
- naphtols (1)
- pH sensors (1)
- penicillin (1)
- penicillinase (1)
- phenols (1)
- photoelectrochemistry (1)
- pipes (1)
- plant scanner (1)
- plant stress (1)
- polyaniline (1)
- ratchetting (1)
- reliability analysis (1)
- semantic role labeling (1)
- shakedown analyses (1)
- shotgun sequencing (1)
- speaker attribution (1)
- sterility tests (1)
- sterilization efficacy (1)
- sterilization methods (1)
- tension–torsion loading (1)
- thermal ratcheting (1)
- titanium dioxide photoanode (1)
- ultrathin gate insulators (1)
- validation methods (1)
- vessels (1)
- wound healing (1)
- yield stress (1)
Shock waves, explosions, impacts or cavitation bubble collapses may generate stress waves in solids causing cracks or unexpected dammage due to focussing, physical nonlinearity or interaction with existing cracks. There is a growing interest in wave propagation, which poses many novel problems to experimentalists and theorists.
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.
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.
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.
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.
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.
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.
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.