Robust Assignment of Natural Frequencies and Antiresonances in Vibrating Systems through Dynamic Structural Modification

This paper proposes a novel method for the robust partial assignment of natural frequencies and antiresonances, together with the partial assignment of the related eigenvectors, in lightly damped linear vibrating systems. Dynamic structural modification is exploited to assign the eigenvalues, either of the system or of the adjoint system, together with their sensitivity with respect to some parameters of interest. To handle with constraints on the feasible modifications, the inverse eigenvalue problem is cast as a minimization problem and a solution method is proposed through homotopy optimization. Variables lifting for bilinear and trilinear terms, together with bilinear and double-McCormick’s constraints, are exploited to provide a convexification of the problem and to boost the attainment of the global optimum. The effectiveness of the proposed method is assessed through four numerical examples.

Antiresonance Assignment in Point and Cross Receptances for Undamped Vibrating Systems

This paper proposes an inverse structural modification method for the assignment of antiresonances in undamped vibrating systems by modifying the inertial and elastic properties of the existing degrees of freedom of the original system. Hence, no additional degrees of freedom are added to the system. The problem is formulated as an eigenstructure assignment approach since such a novel formulation is suitable for complex systems, such as those modeled through finite elements. Indeed, these systems are difficult to handle with the methods already proposed in the literature. Additionally, the proposed approach is suitable for both point and cross receptances. Assignment is cast as a constrained non-convex non-linear minimization problem and the proposed solving strategy is based on the homotopy optimization approach. The method effectiveness is shown through three meaningful test cases.