تحليل لوله هاي كامپوزيتي تحت خمش با استفاده از معيارهاي شكست لايه هاي كامپوزيتي

چكيده انگليسي :

Composite Tubes analysis under Bending by fracture theories for composite laminates By Mohammad Siahkar msiahkar@yahoo com 2010 Department of mechanical engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisors Hosein Moghbel Dr Mahmoud Farzin farzin@cc iut ac irAbstractDue to light weight and high stiffness in bending composite tubes are increasingly used in automobile printing sport and aerospace industries Modeling and design of these tubes are the goal of this research For thispurpose finite element analyses were performed by ABAQUS software For analyses of these tubes a general knowledge about various failure criteria are required These criteria areintroduced in this thesis and among those Puck criterion which is one of best failure theories of this materials isused Besides this criterion degradation equations have been implemented in UMAT subroutine that leads to anonlinear solution This nonlinear solution gives us a better behavior of composite material based onexperimental parameters Bending stiffness of laminated composite tubes is determined experimentally usingfour point bending test Effects of tube inner radius and stacking sequence and fiber orientation of the walled thickness laminate 0 plylocation and fiber material on bending stiffness and strength of composite tubes are studied This project presents a unique and comprehensive comparison between the predictions of internationallyrecognized failure theories for fiber reinforced polymer composite laminates by the World Wide FailureExercise WWFE Whereby 15 of the leading theories for predicting failure in composite laminates have beentested against experimental evidence It is essential to distinguish between fiber failure and inter fiber failure by separate failure criteria After crackinitiation the stiffnesses of the affected plies degrade gradually with increasing load until fiber fracture in oneply provokes ultimate failure of the laminate Various theories and their originators or their colleagues arecarefully selected to cover a wide range of lay ups materials and in plane loading conditions Whereas FiberFailure FF inevitably leads to total failure of the laminate certain Inter Fiber Failure IFF modes are tolerablefor many applications like for example pressure vessels When IFF occurs in a layer the stiffness of this layer is lowered and part of its load is transferred to other layersof the laminate leading that layer to higher stresses and potentially to further failure This so called gradualfailure process has so far not been considered in stress and strength analysis of Fiber Reinforced Polymer FRP components based on the Classical Laminate Theory CLT This degradation issue is covered in this thesis The comparison has been performed through 14 carefully selected test cases by the World Wide FailureExercise which includes biaxial strength envelopes for a range of unidirectional and multi directional laminates and stress strain curves for a range of multi directional laminates loaded under uniaxial or biaxial conditions The predictions and experimental data have been compared in a systematic and detailed manner to identify thestrengths and weaknesses of each theory together with a ranking of the overall effectiveness of each theory Careful reading of these analyses and study of the figures provided will inform the reader when selecting thePuck failure theory for a given design situation Key wordsComposite material Puck criteria Tube FEA ABAQUS four point bending test subroutine UMAT degradation

سياهكار، محمد

تحليل لوله هاي كامپوزيتي تحت خمش با استفاده از معيارهاي شكست لايه هاي كامپوزيتي

Abaqus , معيار شكست پاك , WWFE , روش كاهش خواص , ساپروتين , UMAT , سختي خمش