Analysis of tongue and groove joints for thick
laminates
K. Matous and George J. Dvorak
Department of Mechanical Engineering, Aeronautical
Engineering and Mechanics
Rensselaer Polytechnic Institute
110 8th Street, Troy, NY 12180
Abstract
A finite element evaluation of local stresses in the
adhesive and adherends is presented for a
tongue-and-groove joint of a homogenized thick composite
laminate to steel plate. The quasi-isotropic laminate is
made of glass fabric/vinyl ester plies. Most results are
obtained for elastic response of the Dexter-Hysol 9338
adhesive that was used in recent experiments (Dvorak,
G.J., Zhang, J. and Canyurt, O., ``Adhesive Tongue and
Groove Joints for Thick Composite Laminates'',
Composites
Science and Technology,
61, 1123-1142
(2001)). A nonlinearly viscoelastic adhesive is also
considered, with illustrative properties taken from
experiments on the FM-73 system. Both in-plane force
resultants and out-of-plane moments are included in the
applied loads. Scaling of the elastic results with regard
to plate thickness shows that for given levels of overall
stresses applied to the adherend plates, the stresses
supported by the adhesive do not depend on plate
thickness. Adhesive stress relaxation is shown to be
relatively small, and occurring in a short time period.
Conclusions
The results illustrate the stress distributions
encountered in adhesive tongue and grove joints of thick
laminated composite plates. As in other joint
configurations, the stress concentrations at the adhesive
leading edge depend on the local geometry of the
adherends. However, for given values of stresses in plate
sections removed from the joint, the stresses in the joint
remain independent of a plate thickness. This is a
significant advantage that does not hold in conventional
lap joints, and thus favors use of tongue and grove joints
of different configurations in joining of thick laminates,
where the unavoidable stress concentrations at the
adhesive leading edge can be amply supported by the high
in-plane strength of the laminated plate. Consideration of
the viscoelastic response of the adhesive indicates a
relatively small relaxation of the local stresses, within
a fairly short time period.
Acknowledgment
The authors appreciate financial support of this work by
the Ship Structures and Systems S&T Division of the
Office of Naval Research. Dr. Yapa D.S. Rajapakse served
as program monitor.