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Keywords: fatigue, fibre-reinforced plastics, layer-based concept, energy-based concept, strength degradation, stiffness degradation, failure mechanisms, sequence effects, composites.

Summary

This paper presents a novel fatigue analysis procedure for fibre-reinforced polymer-composite laminates composed of unidirectional (UD) laminae. It consists mainly of a continuum mechanics approach on the macro scale which has been embedded in the commercial finite element code AbaqusR as a material routine for shell elements.

The present applied fatigue analysis procedure is based on the linear damage accumulation rule according to Miner [1] and does not take the multiphase and complex failure behaviour of fibre-reinforced plastics (FRP) into account, a proposal is made for a failure mode dependent analysis which makes use of Puck's failure mode concept [2]. The present concept combines Puck's concept with continuous stiffness degradations caused by fatigue loading and strength degradations. For general applicability the procedure is a layer-wise approach and overcomes therewith the need for experimentally testing the fatigue behaviour of each laminate lay-up.

In contrast to other published fatigue analysis concepts the present procedure couples strength and stiffness degradation and distinguishes between tensile and compressive loading. In order to determine the fatigue-related continuous degradation an energy-based hypothesis is used, which was originally applied to structures made of reinforced concrete [3]. As a result of the high number of load cycles, structures made of FRPs are usually exposed to, a cycle-by-cycle analysis is avoided and a block-wise approach or a cycle-jump strategy is preferred. The concept concentrates on shell elements since the structures to be investigated are generally shell-like and these elements are computationally efficient.

The current, intermediate state of the concept is already tested and shows promising results. By applying different loading sequences to an open-hole structure interesting sequence effects could be investigated.

References

1: M.A. Miner, "Cumulative damage in fatigue", Journal of Applied Mechanics, 67, A159-A164, 1945.
2: A. Puck, "Festigkeitsanalyse von Faser-Matrix-Laminaten - Modelle für die Praxis", Carl Hanser, München, 1996. also in M. Knops, "Analysis of Failure in Fiber Polymer Laminates: The Theory of Alfred Puck", Springer, Germany, 2008.
3: D. Pfanner, "Zur Degradation von Stahlbetonbauteilen unter Ermüdungsbeanspruchung" ("Degradation of Structures Made of Reinforced Concrete under Fatigue Loading"), PhD-Thesis, Ruhr-Universität Bochum, 2000.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 93 PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping, J.M. Adam, F.J. Pallarés, R. Bru and M.L. Romero Paper 79 A Physically Motivated and Layer-based Fatigue Concept for Fiber-Reinforced Plastics H. Krüger and R. Rolfes Institute of Structural Analysis (ISD), Leibniz Universität Hannover, Germany doi:10.4203/ccp.93.79 purchase the full-text of this paper Full Bibliographic Reference for this paper H. Krüger, R. Rolfes, "A Physically Motivated and Layer-based Fatigue Concept for Fiber-Reinforced Plastics", in B.H.V. Topping, J.M. Adam, F.J. Pallarés, R. Bru, M.L. Romero, (Editors), "Proceedings of the Tenth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 79, 2010. doi:10.4203/ccp.93.79 Keywords: fatigue, fibre-reinforced plastics, layer-based concept, energy-based concept, strength degradation, stiffness degradation, failure mechanisms, sequence effects, composites. Summary This paper presents a novel fatigue analysis procedure for fibre-reinforced polymer-composite laminates composed of unidirectional (UD) laminae. It consists mainly of a continuum mechanics approach on the macro scale which has been embedded in the commercial finite element code AbaqusR as a material routine for shell elements. The present applied fatigue analysis procedure is based on the linear damage accumulation rule according to Miner [1] and does not take the multiphase and complex failure behaviour of fibre-reinforced plastics (FRP) into account, a proposal is made for a failure mode dependent analysis which makes use of Puck's failure mode concept [2]. The present concept combines Puck's concept with continuous stiffness degradations caused by fatigue loading and strength degradations. For general applicability the procedure is a layer-wise approach and overcomes therewith the need for experimentally testing the fatigue behaviour of each laminate lay-up. In contrast to other published fatigue analysis concepts the present procedure couples strength and stiffness degradation and distinguishes between tensile and compressive loading. In order to determine the fatigue-related continuous degradation an energy-based hypothesis is used, which was originally applied to structures made of reinforced concrete [3]. As a result of the high number of load cycles, structures made of FRPs are usually exposed to, a cycle-by-cycle analysis is avoided and a block-wise approach or a cycle-jump strategy is preferred. The concept concentrates on shell elements since the structures to be investigated are generally shell-like and these elements are computationally efficient. The current, intermediate state of the concept is already tested and shows promising results. By applying different loading sequences to an open-hole structure interesting sequence effects could be investigated. References 1 M.A. Miner, "Cumulative damage in fatigue", Journal of Applied Mechanics, 67, A159-A164, 1945. 2 A. Puck, "Festigkeitsanalyse von Faser-Matrix-Laminaten - Modelle für die Praxis", Carl Hanser, München, 1996. also in M. Knops, "Analysis of Failure in Fiber Polymer Laminates: The Theory of Alfred Puck", Springer, Germany, 2008. 3 D. Pfanner, "Zur Degradation von Stahlbetonbauteilen unter Ermüdungsbeanspruchung" ("Degradation of Structures Made of Reinforced Concrete under Fatigue Loading"), PhD-Thesis, Ruhr-Universität Bochum, 2000. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
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