A detailed experimental programme of work is presented which examines the c
onstrained torsional response of carbon fibre composite beams for the canti
levered configuration with torque applied at the free end. The behaviour of
open-section beams and that of single-cell closed-section box beams is rep
orted and discussed and the experimental findings are shown to corroborate
simple engineering theoretical approaches. Tests have been carried out on z
ed and angle-section beams and thus the effects of primary and secondary wa
rping restraint respectively on the torsional response of open-section beam
s are examined; The behaviour of zed-section beams is governed, in the main
, by primary effects and that of angle-section beams is associated solely w
ith secondary effects. The stress distributions along the beams and around
the cross-sections are determined from the measured strains during test obt
ained from surface bonded strain gauges and comparison of these with theory
is shown to be in good agreement. The essential differences in response to
constrained torsion between open and closed-section beams are detailed in
the paper and the importance of experimental tests in the analysis of compo
site structures is highlighted. (C) 1998 Published by Elsevier Science Ltd.
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