600 Technik, Technologie
Refine
Document Type
- Conference Proceeding (13)
- Article (11)
- Lecture (1)
Language
- English (25) (remove)
Keywords
- Einspielen <Werkstoff> (10)
- FEM (6)
- Blitzschutz (5)
- Finite-Elemente-Methode (5)
- Einspielanalyse (3)
- Elektromagnetischer Schutzschild (3)
- Lightning (3)
- Shakedown (3)
- Traglastanalyse (3)
- shakedown (3)
- shakedown analysis (3)
- Analytischer Zulaessigkeitsnachweis (2)
- Direkter Blitzschlag (2)
- Einspiel-Analyse (2)
- Erneuerbare Energien (2)
- Hybridsystem (2)
- Induzierte Spannungen (2)
- Lightning protection (2)
- Magnetische Felder (2)
- Risikoabwägung (2)
- Shakedown analysis (2)
- Traglast (2)
- electromagnetic shielding (2)
- limit analysis (2)
- limit load (2)
- ratchetting (2)
- reinforced concrete (2)
- Alternating plasticity (1)
- Analysis (1)
- Axialbelastung (1)
- Axially cracked pipe (1)
- Basis Reduktion (1)
- Basis reduction (1)
- Biomedizinische Technik (1)
- Blitz (1)
- Blitzrisiko (1)
- Blitzschlag (1)
- Bruchmechanik (1)
- Cement infiltration (1)
- Convex optimization (1)
- Deformation (1)
- Design-by-analysis (1)
- Direct lightning strike (1)
- Druckbeanspruchung (1)
- Druckbehälter (1)
- Druckbelastung (1)
- Druckgeräte (1)
- Einspiel-Kriterium (1)
- Einspielen (1)
- Elektromagnetische Kopplung (1)
- Experiment (1)
- Fehlerstellen (1)
- Fließgrenze (1)
- Gasturbine (1)
- Global and local collapse (1)
- Grenzwertberechnung (1)
- Industrieanlagen (1)
- Kalkulation (1)
- Knochen (1)
- Knochenbildung (1)
- Knochenchirugie (1)
- Knochendichte (1)
- Kraftwerke (1)
- Lightning Protection (1)
- Lightning Risk (1)
- Lightning protection system (1)
- Limit analysis (1)
- Materialermüdung (1)
- Maßstabsgetreues Modell (1)
- Micro turbine (1)
- Mikrogasturbine (1)
- Nichtlineare Optimierung (1)
- Osteoporose (1)
- Osteoporosis (1)
- Permeability (1)
- Permeabilität (1)
- Photovoltaikanlage (1)
- Plastizität (1)
- Pressure loaded crack-face (1)
- Progressive plastic deformation (1)
- Rapid Prototyping (1)
- Ratcheting (1)
- Ratchetting (1)
- Renewable energy (1)
- Risiko (1)
- Risk (1)
- Risk Assessment (1)
- Risk Management (1)
- Rohr (1)
- Rohrbruch (1)
- Schwammknochen (1)
- Shakedown criterion (1)
- Stahl (1)
- Stahlbeton (1)
- Stahlbetonkonstruktion (1)
- Strukturanalyse (1)
- Temperaturabhängigkeit (1)
- Vertebroplastie (1)
- Vertebroplasty (1)
- Viscous flow (1)
- Viskose Strömung (1)
- Viskosität (1)
- Windenergieanlage (1)
- Wolff's Law (1)
- Wolffsches Gesetz (1)
- Zug-Druck Belastung (1)
- alternierend Verformbarkeit (1)
- bone density (1)
- bone structure (1)
- burst pressure (1)
- burst tests (1)
- calculations (1)
- cancellous bone (1)
- current distribution (1)
- design-by-analysis (1)
- direct method (1)
- electromagnetic coupling (1)
- electromagnetic shield (1)
- fatigue analyses (1)
- finite element analysis (1)
- flaw (1)
- fortschreitende plastische Deformation (1)
- hybrid system (1)
- hybrid-system (1)
- induced voltage (1)
- induced voltages (1)
- konvexe Optimierung (1)
- limit and shakedown analysis (1)
- linear kinematic hardening (1)
- load limit (1)
- lower bound theorem (1)
- magnetic field (1)
- magnetic fields (1)
- material shakedown (1)
- nonlinear kinematic hardening (1)
- nonlinear optimization (1)
- overvoltages (1)
- photovoltaic system (1)
- pipes (1)
- protection measures (1)
- reliability (1)
- reliability analysis (1)
- renewable energy (1)
- risk assessment (1)
- scaled model (1)
- shakedown analyses (1)
- tension–torsion loading (1)
- thermal ratcheting (1)
- vessels (1)
- wind turbine (1)
- yield stress (1)
- Überspannung (1)
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.
The paper deals with the development of the probabilistic approach to the assessment of risk due to lightning. Sources of damage, types of damage and types of loss are defined and, accordingly, the procedure for risk analysis and the way of assessment of different risk components is proposed. The way to evaluate the influence of different protection measures (lightning protection system; shielding of structure, cables and equipment; routing of internal wiring; surge protective device) in reducing such probabilities is considered. The paper has been prepared within the framework of the activity of IEC TC81-WG9/CLC TC81-WG4 directed to prepare the draft IEC 62305-2 Risk Management, in cooperation with the Secretary of IEC/CLC TC81.
Rapid Prototyping Technology: Types of models, rapid prototyping processes, prototyper Fundamentals of rapid prototyping Industrial rapid prototyping technology: Stereolithography, (Selective) laser sintering ((S)LS), Layer laminate manufacturing (LLM), Fused layer modeling (FLM), Three dimensional printing (3DP)
In the paper the results obtained from experiments at a modelled reinforced building in case of a direct lightning strike are compared with calculations. The comparison includes peak values of the magnetic field Hmax, its derivative (dH/dt)max and of induced voltages umax in typical cable routings. The experiments are performed at a 1:6 scaled building and the results are extrapolated using the similarity relations theory. The calculations are based on the approximate formulae given in IEC 62305-4 and have to be supplemented by a rough estimation of the additional shielding effect of a second reinforcement layer. The comparison shows, that the measured peak values of the magnetic field and its derivative are mostly lower than the calculated. The induced voltages are in good agreement. Hence, calculations of the induced voltages based on IEC 62305-4 are a good method for lightning protection studies of buildings, where the reinforcement is used as a grid-like electromagnetic shield.
In the paper a lightning protection design concept for renewable energy hybrid-systems without power mains connection is described. Based on a risk analysis protection measures against direct strikes and overvoltages are shown in an overview. The design concept is realized exemplarily for the hybrid-system VATALI on the Greek island Crete. VATALI, not lightning protected at that time, was a victim of a lightning strike in the year 2000 causing destructions and damages of some mechanical and electrical components with costs of approx. 60.000 €. The hardware costs for the protection measures were about 15.000 €: about 50% of the costs are due to protection measures against direct strikes, 50% are due to overvoltage protection.
Lightning protection design of a renewable energy hybrid-system without power mains connection
(2001)
In the year 2000 a direct lightning strike to the hybridsystem without power mains connection VATALI on the Greek island Crete results in the destruction and damage of some mechanical and electrical components. The hybrid-system VATALI was not lightning protected at that time. The hardware damage costs are approx. 60,000 €. The exposed site of the hybrid-system on top of a mountain was and still is the reason for a high risk of lightning strikes. Also in the future further lightning strikes have to be taken into consideration. In the paper a fundamental lightning protection design concept for renewable energy hybrid-systems without power mains connection and protection measures against direct strikes and overvoltages are shown in detail. The design concept was realized exemplarily for the hybrid-system VATALI. The hardware costs for the protection measures were about 15,000 €. About 50% of the costs are due to protection measures against direct strikes, 50% are due to overvoltage protection. Future extensions, new installations, or modifications have to be included into the lightning protection design concept of the hybrid-system.
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.
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.
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.