Transfer Project T4

Assessment of Numerical Investigated Robustness of (Textile Reinforced) Structures

Director

Prof. Dr.-Ing. Wolfgang Graf; federführend
Prof. Dr.-Ing. habil. Bernd Möller
Institute of Structural Analysis

Staff

Dipl.-Ing. Stephan Pannier

Partner Institution

DYNAmore GmbH

Contact persons: Dr.-Ing. Thomas Münz, Dipl.-Ing. Marko Thiele

Objectives

The algorithms and models for uncertain numerical simulations, developed in the CRC 528 for textile reinforced concrete structures are transfered to other classes of structures. The stress of the praxis relevant processing tends to the assessment of robustness of structures.

The robustness is an important design criteria for (textile reinforced) structures. It denotes an high independence of the structural responses while changing the structural parameters. A robust structure operates faultless over a defined period of time. The assessment of robustness requires on the one hand the consideration of uncertainty of geometrical, matirial and load parameters and on the other hand an suitable measure of the robustness. GENICHI TAGUCHI defined robustness as follows

Not just strong. Flexible! Idiot Proof! Simple! Efficient! A product/process that produces consistent, high level performance despite being subjected to a wide range of changing client and manufacturing conditions.

The quantification of robustness demands a comprehensive appraisal of uncertainty. The character of uncertainty is not always random describing (textile reinforced) structures. Therefore the utilization of stochastic methods are not always appropriate. Constitutive to the well-founded theory of random variables the basics for the assessment of informal and lexical uncertainty are enhanced in numerous research activaties. A mathematical approach is - beside stochastic - the fuzzy set theory handling interval variables and deterministic values as a special case and fuzzy-randomness containing random variables as s special case. The generalized algorithms and models of uncertainty developed in CRC 528 are transfered to other classes of structures possessing significant data uncertainty, too. The transfer project is to have a share in minimizing the scientific gap between mathematic and engineering science/practice utilizing all kinds of uncertainty models.

The uncertain structural analysis is exemplified for textile reinforced structures in the CRC 528. As a result there are a lot of valid designs, which should be assessed under the aspect of robustness. Therefore a new definition of robustness, based on the SHANNONs entropy, is introduced. Further uncertain measures such as energy measures should be investigated.

Structural analyses close to reality demand the utilization of computational numerical simulations, e.g. finite element methods (FEM). The steady enhancement and the increasing complextiy of the numerical models run up the computational costs. The concept of fuzzy stochastic finite elements (FSFEM) was investigated in CRC 528 (project D2 and project E3). It requires the repeated execution of the deterministic fundamental solution. An application under a practical point of view is limited to the computational cost. The realization demands the utilization of metamodels. In the future the application, enhancement and real world preparation of metamodels has to be a new component of the transfer project.

An further aim of the transfer project is the setup of a data library about manufacturing fluctuations and the development of an interface between data library and uncertain analysis algoritm. This is the basis for the assessment of different structures.

Methods

The realization of the subprojekt is based on scientific mehtods for research and development of numerical computational algorithms. Sources are the theory of fuzzy random variables, the fuzzy set theory, the possibility theory and the stochastic. The utilized concepts base on generalized theoretical approaches of uncertainty.

The algorithms are implemented into the software environment, which is the requirement for numerical test and parameter studies.

Numerical tests require data revtrieval, specification of uncertainty and the interpretation of datas as fuzzy variables and fuzzy random variables respectively. A professional discussion with colleagues about the degree of safety in the codes is the basis for the interpretation of numerical test results. The cooperating partner ensures further professional discussions with structural designers.

Results

The transferproject T4 has been finished in the end of 2008 successfully. In result the methods, developed in CRC 528, are transfered in the engineering application. This is documented by numerous papers and presentations on national and interantional conferences. Due to the success of the transferproject T4 and a great interest for the research results of the CRC 528 a new transferproject T7 together with the partners BMW AG and DYNAmore GmbH are initiated.

A robustness assessment bases on an appropriate description of the input quantitities. The available information/ data are not always objective, but especially in the engineering application characterized subjectively. This call for the application of data analysis methods by the respective expert himself. Under consideration of the requirements in the engineering practice a web portal for data analysis of non-random quantities was set up within this project. The focus for this web portal was set on a practice-oriented usability by means of a graphical user interface. Additionally, the web portal contains an open access database with personalized data management and hierarchic data structure. This enables the administration of research results from the CRC 528.

The fuzzy stochastic finite element method was demonstrated by means of practice-oriented examples of the partner DYNAmore GmbH, in collaboration with Daimler AG (pdf-file). By means of the obtained results it has been shown, that the new developed methods to model data uncertainty for the numerical simulation enable a more realistic description of strucural behavior/ processes.

To assess the robustness of structures/ processes new robustness measures on the basis of energetic formulations are developed and introduced. Based on the results of FSFEM, their appropriateness was demonstrated and compared to the results of traditional robustness measures.

Publications

2009

• Sickert, J.-U.; Graf, W.; Pannier, S.: Entwurf von Textilbetonverstärkungen - computerorientierte Methoden mit verallgemeinerten Unschärfemodellen. In: Curbach, M. (Hrsg.), Jesse, F. (Hrsg.): Textile Reinforced Structures : Proceedings of the 4th Colloquium on Textile Reinforced Structures (CTRS4) und zur 1. Anwendertagung, Dresden, 3.-5.6.2009. SFB 528, Technische Universität Dresden, D–01062 Dresden : Eigenverlag, 2009, S. 313-324 URN: urn:nbn:de:bsz:14-ds-1244047293129-54264
• Piotrov, A.; Liebscher, M.; Pannier, S.; Graf, W.: Grouping detection of uncertain structural processes by means of cluster analysis. In: 7. European LS-DYNA Conference, Salzburg, 2009. Proceedings, S. 128 and CD-ROM (11 S.)
• Sickert, J.-U.; Pannier, S.; Graf, W.; Jenkel, C.: Robustness assessment of structures incorporating generalized uncertainty models. In: Furuta, H.; Frangopol, D.M.; Shinozuka, M. (eds.): Safety, Reliability and Risk of Structures, Infrastructures and Engineering Systems, Proceedings of the 10th International Conference on Structural Safety and Reliability (ICOSSAR2009). London : Taylor & Francis, p. 111, Volltext (8 S.), CD-ROM
• Pannier, S.; Sickert, J.-U.; Graf, W.: Patchwork approximation scheme for reliability assessment and optimization. In: Furuta, H.; Frangopol, D.M.; Shinozuka, M. (eds.): Safety, Reliability and Risk of Structures, Infrastructures and Engineering Systems, Proceedings of the 10th International Conference on Structural Safety and Reliability (ICOSSAR2009). London : Taylor & Francis, p. 531, Volltext (8 S.), CD-ROM
• Möller, B.; Liebscher, M.; Pannier, S.; Graf, W.; Sickert J.-U.: An inverse solution of the lifetime-oriented design problem. In: Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance (2009), online available – doi:10.1080/15732470802658946

2008

• Freitag, S.; Graf, W.; Pannier, S.; Sickert, J.-U.: Reliability of structures under consideration of uncertain time-dependent material behaviour. In: Dubois, D. et al. (eds.): Adcances in Soft Computing 48. Soft Methods for Handling Variability and Imprecision. Berlin : Springer, 2008, pp. 383-390 4th Internat. Conference on Soft Methods in Probability and Statistics, Toulouse, 2008
• Pannier, S.; Sickert, J.-U.; Graf, W.: Optimization under consideration of uncertain input quantities. In: GAMM-Tagung, Bremen, 2008. – CD-ROM
• Sickert, J.-U.; Graf, W.; Pannier, S.: Strengthening with textile reinforced concrete reliability based design with imprecise probability. In: Bondindi, F.; Fangopol, D. (eds.), 1st International Symposium on Life-Cycle Civil Engineering, Varenna. CRC Press, Boca Raton, Taylor & Francis Group : London, 2008, pp. 463-468
• Graf, W.; Pannier, S.; Sickert, J.-U.: Response surfaces models for uncertain structural analysis. In: Schreffler, B.; Perego, U. (eds.): 8th World Congress Computational Mechanics, Venedig, 2008. Abstract, CD-ROM
• Jenkel, C.; Graf, W.; Pannier, S.; Sickert, J.-U.: Structural health monitoring under consideration of uncertain data. In: 7. LS-DYNA Forum 2008, Bamberg. Kap. F-I, pp. 1-10
• Pannier, S.; Sickert, J.-U.; Graf W.: Optimization under consideration of uncertain input quantities. PAMM 8 (2008) pp. 10781-10782 – doi:10.1002/pamm.200810781
• Pannier, S.; Graf, W.; Müllerschön, H.; Liebscher, M.: Simulation of metal forming processes under consideration of imprecise probabilities. In: 7. LS-DYNA Forum 2008, Bamberg. Kap. C-III, pp. 37-48

2007

• E. Mistakidis, R. Apostolska (Petrusevska), D. Dubina, W. Graf, G. Necevska-Cvetanovska, P. Nogueiro, S. Pannier, J.-U. Sickert, L. Simões da Silva, A. Stratan, U. Terzic: Typology of seismic motion and seismic engineering design. In: Urban Habitat Constructions Under catastrophic Events. COST Action C26, WG 2, Proceedings of Workshop, Prag, 2007, pp. 130-158
• M. Liebscher, M. Beer, S. Pannier, M.Thiele, W.Graf: Sampling schemes for crashworthiness investigations in view of robustness and reliability. In: COMPDYN 2007 – Computational Methods in Structural Dynamics and Earthquake Engineering (Thematic Conference of ECCOMAS). 2007
• H. Müllerschön, D. Lorenz, W. Roux, M. Liebscher, S. Pannier, K. Roll: Probabilistic analysis of uncertainties in the manufactureing process of metal forming. In: 6th European LS-DYNA Users´ Conference, Gothenburg. 2007
• B. Möller, W. Graf, M. Liebscher, S. Pannier, J.-U. Sickert: An inverse solution of the lifetime-oriented design problem. In: 3rd International Conference Lifetime-Oriented Design Concepts ICLODC 2007, Bochum. 2007, pp. 21-40
• S. Pannier, M. Liebscher, M. Beer, W. Graf: Fuzzy stochastic simulation of deep drawing processes. In: EUROMECH Colloquium 482 – Efficient Methods for Robust Design and Optimisation, London. 2007, CD-ROM
• S. Pannier, M. Beer, M. Liebscher, W. Graf: Response Surface Simulation – Patchwork Application. In: 6th German LS-DYNA Forum, Frankenthal. 2007

2006

• Freitag, S.; Graf, W.; Hoffmann, A.; Pannier, S.; Sickert, J.-U.; Steinigen, F.: Tragwerke aus Textilbeton – unscharfe numerische Simulation. In: Ruge, P.; Graf, W. (eds.): 10. Dresdner Baustatik-Seminar. Dresden, 2006, S. 123-132 – PDF-Datei, 544 kB
• Liebscher, M.; Pannier, S.; Sickert, J.-U.; Graf, W.: Efficiency Improvement of Stochastic Simulation by Means of Subset Sampling. In: 5th LS-DYNA Forum 2006. Ulm, 2006, p. K-I-41–K-I-56