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In-plane finite element approach for analyzing manufacturing defects in composite materials

Khattab, Imad Al-din. and Sinapius, Michael and Hartung, Daniel (2010) In-plane finite element approach for analyzing manufacturing defects in composite materials. 16th international conference MECHANICS OF COMPOSITE MATERIALS, 24. - 28. Mai 2010, Riga, Latvia.

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Abstract

Fiber composite materials provide low material weights in combination with high material stiffness and strength. The fiber stiffness and strength characterize mainly the behavior of unidirectional composites plies. The single ply behavior is highly sensitive to variations of fiber orientations, fiber misalignments or the fiber volume content. Critical phenomena for composite structures are defects caused by the manufacturing and processing technologies. It is has been shown by many authors during the last years that the analysis of manufacturing defects in composite structures is a complex problem. Critical defects being often detected are fiber misalignment and elliptical voids caused by porosities due to gas enclosures during the infiltration and curing process. These defects substantially influence the stiffness and strength of composite structures. Therefore it is very important to develop a method which is able to determine critical defects and precisely analyze the effects of these defects. The paper will present an appropriate In-plane finite element model for the analysis of the effects of fiber waviness on the stiffness of unidirectional composites under shear and tensile loading conditions. The ply and roving orientations are considered with a meso-level approach. The element coordinate system is consequently reoriented to the fiber direction according to the curvature of the fibers. The approach uses laminates with different waviness and regular fiber oriented layers. The investigation is also capable to study the effect of in-plane elliptical voids in lamina surrounded with curved fibers on the stiffness. The built-in Hashin failure and damage model in ABAQUS is utilized to model the failure of uniform fiber waviness, graded fiber waviness and the influence of elliptical voids on the strength of a composite ply under pure shear and pure tensile loading conditions along and transverse to the fiber direction. The study enables the validation of the unidirectional fiber stiffness as function of waviness with analytical approaches for two kinds of curved fibers: uniform and graded fibers waviness. Finally, we will present a multi-scale approach via the sub-modeling technique of ABAQUS-CAE. This enables the connectivity of local models in meso-level with macro-level structures and the computation of large structures for industrial purposes.

Document Type:Conference or Workshop Item (Speech)
Title:In-plane finite element approach for analyzing manufacturing defects in composite materials
Authors:
AuthorsInstitution or Email of Authors
Khattab, Imad Al-din.University of Magdeburg, Department of Mechanical Engineering
Sinapius, MichaelUNSPECIFIED
Hartung, DanielUNSPECIFIED
Date:24 May 2010
Refereed publication:Yes
In ISI Web of Science:No
Keywords:Fiber composite materials, defects, finite element model
Event Title:16th international conference MECHANICS OF COMPOSITE MATERIALS
Event Location:Riga, Latvia
Event Type:international Conference
Event Dates:24. - 28. Mai 2010
Organizer:Institute of Polymer Mechanics, University of Latvia
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:other
DLR - Research area:Aeronautics
DLR - Program:L - no assignement
DLR - Research theme (Project):L -- no assignement
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems
Deposited By: Doris Ries
Deposited On:03 Jun 2010 10:39
Last Modified:21 Jun 2010 10:37

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