Affiliations: Department of Mechanical Engineering, Escola Superior
de Tecnologia, Polytechnic Institute of Setúbal Campus do IPS, Estefanilha,
2910-761 Setúbal, Portugal | Department of Mechanical Engineering, Instituto
Superior Técnico, Technical University of Lisbon Av. Rovisco Pais, 1049-001
Lisboa, Portugal
Abstract: The dynamic response of a structure can be described by both its
translational and rotational receptances. The latter ones are frequently not
considered because of the difficulties in applying a pure moment excitation or
in measuring rotations. However, in general, this implies a reduction up to
75% of the complete model. On the other hand, if a modification includes a
rotational inertia, the rotational receptances of the unmodified system are
needed. In one method, more commonly found in the literature, a so called
T-block is attached to the structure. Then, a force, applied to an arm of the
T-block, generates a moment together with a force at the connection point. The
T-block also allows for angular displacement measurements. Nevertheless, the
results are often not quite satisfactory. In this work, an alternative method
based upon coupling techniques is developed, in which rotational receptances
are estimated without the need of applying a moment excitation. This is
accomplished by introducing a rotational inertia modification when rotating the
T-block. The force is then applied in its centroid. Several numerical and
experimental examples are discussed so that the methodology can be clearly
described. The advantages and limitations are identified within the practical
application of the method.
