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Analytical Prediction of Failure Strength of Co-cured Composite Skin-Stiffener Joints

IR@NAL: CSIR-National Aerospace Laboratories, Bangalore

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Title Analytical Prediction of Failure Strength of Co-cured Composite Skin-Stiffener Joints
 
Creator Banker, Manisha M
Varughese, Byji
 
Subject Structural Mechanics
 
Description Composite materials are widely appreciated by the engineers for aerospace applications because of their property tailorability, high specific strength, high specific stiffness, less weight and many other advantages. Various technologies are used worldwide for fabrication of these composite structures. One of such state of the art technologies is co-curing, where the primary structure is co-cured along with the secondary structure by eliminating the fasteners and allowing many other benefits of co-curing. The integral structure realized through co-curing approach will result in cost benefits by reducing the part count, fasteners and assembly time. Such type of fabrication is adopted in transport aircraft wing and empennage structures where the substructure members like spars, ribs etc are co-cured with the skin forming co-cured joints. When such joints are present in wing structures they are subjected to direct or in-direct out-of-plane loads caused by pressure generated due to the presence of fuel. The behavior and the strength of these joints under out-of- plane loads are of concern and has been the topic of many analytical and experimental studies. However, only limited information is available in the open literature. For the present study a typical transport aircraft wing, which is made of composites and fabricated using co-curing technology, is considered. The co-cured wing structure with internal fuel pressure imparting out-of-plane loads on joints are addressed in this paper. The joint strength assessment through feature level test by introducing the same level of defect concentration on such joints would be time consuming and expensive. On the other hand Finite Element (FE) analysis using suitable commercial software with appropriate model of the joint would provide a substantial understanding on the strength of the joint. In the present paper attempts are made to understand the structural behavior of typical co-cured composite joints subjected to pull-off load, in presence and absence of a typical manufacturing defect. The authors demonstrate here the approach to predict the failure strength of co-cured joints under contemplation analytically using a polynomial invariant based three dimensional failure theory. The paper explains the methodology established for predicting failure strength under pull-off load which is a first step towards certification of co-cured joints with and without manufacturing defects.
 
Publisher American Institute for Aeronautics and Astronautics ( AIAA )
 
Type Book / Book Chapter
PeerReviewed
 
Relation http://arc.aiaa.org/doi/pdf/10.2514/6.2014-1532
http://nal-ir.nal.res.in/12035/
 
Identifier Banker, Manisha M and Varughese, Byji Analytical Prediction of Failure Strength of Co-cured Composite Skin-Stiffener Joints. In: 55th AIAA/ASME/ASCE/AHS/SC Structures, Structural Dynamics and Materials Conference 2014. American Institute for Aeronautics and Astronautics ( AIAA ), Proceedings of a meeting held 13-17 January 2014, National Harbor, Maryland, USA. Held at the AIAA SciTech Forum 2014. ISBN 978-1-63266-929-2