This paper seeks to exploit the reciprocal modal vector orthogonality betwe
en experimentally-derived mode shapes and the corresponding measured freque
ncy response functions in order to derive a criterion for the detection of
structural non-linearities. Being based on the use of measured data and exp
erimentally-derived quantities only, the method is directly applicable to p
ractical engineering cases for which there are usually no spatial descripti
ons. A brief outline of the reciprocal modal vector theory is given first,
followed by a short description of a frequency-domain nonlinear response si
mulation technique using a harmonic balance approach. A detailed study of a
4-DOF system with cubic stiffness and friction damping nonlinearities is p
resented next. It is shown that the proposed nonlinearity detection criteri
on is relatively insensitive to measurement noise. It is concluded that the
method is effective for detecting nonlinear behaviour in a consistent and
quantitative fashion.