Modelling of the Fracture Mechanical Behaviour of Fibre Reinforced Materials with the Finite Element Method
The work analyses the micromechanical and macromechanical failure behavior of fibre-reinforced materials on hand of two examples.
Subject of the first part is the ‘Curved-Double-Cantilever-Beam’-Test which is used for characterization of delamination toughness of curved thermoplastic composite samples. It is investigated with a finite element model by a macroscopic, fracture mechanics approach. The presented finite element analysis provides a reliable basis for the estimation of the critical debonding energy release rate Gc from the experimental results and is used for the formulation and verification of a simple, empirical data reduction scheme. The theoretical investigation is complemented with an experimental study for glass-fibre/ polyamid 6 samples.
The second example refers to a micro- and fracture mechanical description of fibre-matrix-interface failure in the single-fibre-pull-out-test. The intention was to replace critical interface-shear-strength by a fracture-mechanical debonding criterion. Particularly the initial phase of interface-crack-extension is characterized by dominant and quickly changing mode-I-contributions. Maximum debonding force- as the most significant experimental result- is ob-served in this range. For medium crack lengths the energy release rate G of interface crack extension passes a stationary plateau with only small changes in mixed mode loading state. The value of G can be approximated by that of the free fibre contribution from a very simple analytic expression. The stable crack growth mode should offer more reliable conditions for the experimental estimation and the comparison of interfacial properties from different material systems. As a consequence from the experimental results the effects of interface friction have to be considered in the analysis, which is possible in an approximate way by help of an analytical extension to the FE-results. The experiments confirm the view of interfacial failure, supplied by the model.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
fibre composite materials, fibre-matrix-adhesion, finite element analysis, fracture mechanics, test evaluation, single fibre pull-out test, curved cantilever beam test
Institute / chair: Fachbereich Maschinenwesen der Universität Kaiserslautern
Technical consultant for expert services: Prof. Dr.-Ing. K. Friedrich, PD Dr. rer. nat. habil. B. Lauke
Publication year: 1995
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
About the PhD Dissertation Data Base
In cooperation with the Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK), we provide free access to current dissertations in the field of plastics technology.