Abstract: | In modal frequency response analysis, the dynamic analyst is often faced with the structure’s dynamic behavior, the modal
contributions included, over a frequency window rather than at a single frequency. Therefore a new method in modal frequency
response analysis has been developed for computing both complex modal-contributions and real, actual modal-contributions over
a frequency range. Contributions from normal modes to displacement, velocity, or acceleration of a set of selected evaluation
points (grid-component combinations) are considered. The focus lies on identifying the major actual-contributions from normal
modes and the frequency range they are active in. The method is valid for all branches of mechanical engineering. With the
thorough knowledge of the dominant modal-contributions to the physical motion response of relevant structure locations and
the modal contributions’ frequency history, the traditional design process can substantially be enhanced. It is worthwhile
to notice that by the use of the presented procedure the dynamic analyst may find innovative redesigns which the automatic
structural optimizers are not able to find. Examples are given to demonstrate the application, the strength of the coupling
between modes, the influence of base and force excitation on the modal contributions and, finally, some recommendations on
how to reduce undesired structural responses. |