Study on robust structures (3rd report, design method and discussions on dynamic robust structure problems)

A structure with characteristics that are only slightly modified by any changes external forces, boundary conditions, and productive errors has advantages from the engineering point of view. This kind of structure is called `robust structure'. Robust structure problems are classified into the narrow sense and the broad sense. In this paper, dynamic robust structures in the broad sense are discussed. A design method of dynamic robust structures is proposed, which takes an eigenvalue as a reference function. The following three points are clarified from numerical examples of bar and plate structures. First, a dynamic robust structure can be designed when an eigenvalue is chosen as a reference function. Then a structure the mass of which is concentrated near the antinode of the vibration can gain the robustness. Finally, robust structures have advantages when the control system is designed since the optimum control gains have been only slightly affected in comparison with other designed structures.