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Finite Element Approach for Analyzing Manufacturing Defects in Composite Materials

Khattab, Imad Al-din and Sinapius, Michael and Kreikemeier, Janko (2011) Finite Element Approach for Analyzing Manufacturing Defects in Composite Materials. ECCOMAS Thematic Conference “Mechanical Response of Composites”, 21. - 23.09.2011, Hannover, Deutschland.

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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. Critical phenomena for composite structures are defects caused by the manufacturing and processing technologies. One such phenomenon which is often detected is fiber misalignment. The paper presents an appropriate 3D finite element model for the analysis of the effects of in-plane and out-of-plane graded fiber waviness on the stiffness and strength values of a laminate which consists of unidirectional plies under shear and tensile loading conditions. The classical laminate theory (CLT) is utilized as analytical model to predict the unidirectional fiber stiffness as a function of in-plane and out-of-plane fibers waviness. Furthermore the undula-tions of fiber are represented by Fourier series. The 3D linear Hashin failure criterion implemented in ABAQUS is functioned by means of a user subroutine file (i.e. UMAT) to predict the influence of misaligned fibers on the strength of a compos-ite laminate under pure shear and pure tensile loading conditions along and transverse to the fiber direction. In this investigation, parametric studies are carried out on the sensitivity of the effect of fiber misalignment on the stiffness and strength. These parameters are, e.g., material properties, vary-ing degree of fibers and plies waviness, different ply orientation, ply-up of laminate, width and thick-ness of laminate, volume fiber fraction variation with fiber waviness, and mesh size.

Document Type:Conference or Workshop Item (Speech, Paper)
Title:Finite Element Approach for Analyzing Manufacturing Defects in Composite Materials
Authors:
AuthorsInstitution or Email of Authors
Khattab, Imad Al-dinUniversität Magdeburg
Sinapius, MichaelUNSPECIFIED
Kreikemeier, JankoUNSPECIFIED
Date:September 2011
Keywords:cfrp, fibre waviness, classical laminate theory, Hashin criterion
Event Title:ECCOMAS Thematic Conference “Mechanical Response of Composites”
Event Location:Hannover, Deutschland
Event Type:national Conference
Event Dates:21. - 23.09.2011
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation & Validation
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems > Structural Mechanics
Deposited By: Isolde Böhringer-Thelen
Deposited On:06 Oct 2011 15:48
Last Modified:06 Oct 2011 15:48

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