Experimental and theoretical studies of secondary bending of bonded composite butt joints in tension

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DOIResolve DOI: http://doi.org/10.2514/6.2010-3103
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Proceedings titleCollection of Technical Papers : AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
Conference51st AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, April 12-15, 2010, Orlando, Florida
SubjectA-plane; Adherends; Adhesive stress; Basic parameters; Bending stiffness; Butt joints; Closed form; Doublers; Edge region; Finite Element; Joint deformations; Out-of-plane direction; Plane strains; Plane stress condition; Safety margin; Secondary bending; Strain ranges; Theoretical models; Theoretical study; Three dimensional finite element model; Young's Modulus
AbstractThe deformation of adhesively bonded composite butt joints in tension was investigated experimentally, theoretically, and numerically. Two single-strap butt joints were tested, the only difference between them being the thickness of the doubler. The case 1 joint was fabricated using identical laminated composite panels for both the adherends and the doubler, while the case 2 joint had a 50% thicker doubler. Expressions for the effective Young's modulus and bending stiffness for the composite butt joint were derived under both plane strain and plane stress conditions. Joint deformation in the out-of-plane direction and longitudinal elongation could then be theoretically analyzed. A theoretical model for the joint elongation was developed, and an approach was proposed to deal with the strain discontinuity at the overlap end of the joint using the derived theoretical method. Three-dimensional finite element models were created for the analysis of the unit-width joints under a plane strain condition. Good agreement in the predicted joint deformation (deflection, elongation, and strain) was achieved between the three methods. The results suggested that joint bending under both plane strain and plane stress condition should be studied so that the actual strain range in high bend areas (overlap edge regions) can be determined. Expressions for the four basic parameters in the coupled adhesive stress differential equations were also developed and two strategies were presented to explore the complete closed-form adhesive stress solutions in a general composite butt joint configuration. Finite element results showed that peak adhesive stresses were located at the inner overlap edge, and suggested that appropriate reinforcement should be made in this region to ensure a sufficient safety margin.
Publication date
AffiliationNRC Institute for Aerospace Research; National Research Council Canada
Peer reviewedNo
NPARC number21275952
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Record identifier2d270ba9-6935-421e-9dc9-51fdb2422980
Record created2015-08-18
Record modified2016-05-09
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