Dynamic properties of the structures with three level of symmetry

In the field of mechanical engineering, structural systems that can present different types of symmetries are frequently encountered. The choice of such solutions with symmetries is generally the result of considering factors such as reducing design and production costs, logistical considerations, but also for aesthetic reasons. The existence of these symmetries inside some structures brings new properties in the mechanical behavior and can be useful in simplifying the calculation, in the static and dynamic case. Symmetries can bring new properties when the problem of studying vibrations is raised. Thus, the dynamic analysis time can be reduced and the designer can get a quick picture of the behavior of the structure in operation. The paper aims to study a special situation of symmetry that can be encountered in engineering practice, namely the existence of three planes of symmetry within a structure. Such structures can be found frequently in the field of mechanical engineering but also in the construction of buildings. The presented properties can contribute to the reduction of dynamic analysis time and therefore to the reduction of design costs. An example from real life is analyzed in the work, highlighting the listed properties.