Publica
Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. How simulation of failure risk can improve structural reliability  application to pressurized components and pipes
:
Fulltext urn:nbn:de:0011n2592837 (913 KByte PDF) MD5 Fingerprint: f88fa9572e6197859afab036a99e6eb7 Created on: 18.9.2013 
 Boller, Christian (Ed.); Janocha, Hartmut (Ed.) ; Univ. des Saarlandes, Saarbrücken; FraunhoferInstitut für Zerstörungsfreie Prüfverfahren IZFP, Saarbrücken: New trends in smart technologies : 5th ECCOMAS Thematic Conference on Smart Structures and Materials held in Saarbrücken/Germany in the summer of 2011 Stuttgart: Fraunhofer Verlag, 2013 ISBN: 3839605776 ISBN: 9783839605776 pp.6987 
 Thematic Conference on Smart Structures and Materials (SMART) <5, 2011, Saarbrücken> 

 English 
 Conference Paper, Electronic Publication 
 Fraunhofer IZFP () 
Abstract
Probabilistic methods for failure risk assessment are introduced, with reference to load carrying structures, such as pressure vessels (PV) and components of pipes systems. The definition of the failure risk associated with structural integrity is made in the context of the general approach to structural reliability. Sources of risk are summarily outlined with emphasis on variability and uncertainties (V&U) which might be encountered in the analysis. To highlight the problem, in its practical and analysis perspective, a short account is given on the nature of failures encountered in pressure vessels and pipe systems, with essential statistical data of service failure. Two engineering analysis tools are invoked: probabilistic fracture mechanics (PFM) and quantitative nondestructive inspection (QNDI). Probabilistic models for risk estimation, in terms of failure probability, are introduced in the classical view of full distribution approach (convolution integral computation) and direct Monte Carlo random simulation of the governing input variables implied in the failure model. The considered endfailure criterion operates with a performance function derived from the elasticplastic Dugdale crack model, formalized in the failure assessment diagram (FAD) methodology. In the analysis are also integrated probability of detection (POD) models which quantify the chance of flaws/cracks detection by nondestructive inspection, applied intermittently or continuously in a structural health monitoring (SHM) system. he technique of construction of nonparametric confidence intervals on POD vs. crack size rule, by simulated bootstrap resampling is presented, in view of setting, presumably safe initial crack size used in fracture mechanics computations. By merging PFM and QNDI via POD, the benefit of applying nondestructive inspection for the purpose of increasing structural reliability is estimated in terms of the decrease of failure probability. The influence of the quality of nondestructive inspection is reflected by POD rule (model). The quantitative approach, structured as a computer code pvRISK is provided. A case study of failure risk assessment in PVs is presented and discussed in the context of failure risk management by intermittent inspection or by a SHM system. By sensitivity analysis, as concerns the variability of size of cracks that might subsist in the structure the benefit of applying NDI expressed in terms of reducing the probability of failure by fracture is evaluated.