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Uncertainties in the prediction of CFRP laminate properties in the context of a reliability based design approach
Publikationstyp
Conference Paper
Date Issued
2013
Sprache
English
Author(s)
TORE-URI
Start Page
961
End Page
968
Citation
International Conference on Composite Materials 2013 : (ICCM-19) ; Montreal, Quebec, Canada, 28 July - 2 August 2013 / [organized by Canadian Association for Composite Structures and Materials (CACSMA)]. Ed.: Suong Van Hoa. - Red Hook, NY : Curran. - Vol. 2 (2013), Seite 961-968
Contribution to Conference
Scopus ID
Publisher
Curran
© QinetiQ Ltd 2013. In order to pursue a reliabililty based deseiyg approach, material related uncertainties need to be quantified. For composite structural designers, the evaluation starts at the coupon level where a limited number of layups gets tested. The state of the art stiffness determination process then neglects the non-linear stiffness behavior as well as the spatial variability and aims at conservative estimates. In the present work, a unidirectional laminate is tested in tension and the stiffness is evaluated at different loading points. Monte Carlo simulation technique is used to predict laminate stiffnesses based on this data for two different layups and compared to a similar simulation based on constituent properties. The predictive qualities are checked against measured laminate stiffnesses. Furthermore, polynomial curve fits are generated for each specimen and mean and confidence intervals evaluated for a strain working range of interest and compared to the secant method suggested by the respective Norm. A simple beam problem is used to illustrate the consequences of the different stiffness determination methods. In the considered tension case the maximum computed deviation of a specific stress quantile to the reference stress quantile is around 5%. The evaluation methods investigated lead to significantly higher deviations when comparing the respective deflections, thus suggesting that ultimately a more robust testing and evaluation method needs to be applied. This is especially true since in case of stiffness determined designs the usage of a low estimate of the stiffness is not necessarily a conservative assumption.
Subjects
Design philosophy
Mechanical properties
Reliability
Tension testing
DDC Class
620: Ingenieurwissenschaften