Influence mechanism of lumped masses on the flutter behavior of structures

It is well known that lumped masses can change the frequency characteristics of the structural system, and aeroelastic flutter happens due to the coalescence of two modes. Therefore, it can be expected to improve the aeroelastic stability by the lumped mass. This paper studies the influence mechanism of the lumped mass on the aeroelastic behaviors of two-dimensional (2D) panels in supersonic airflow, and proposes an axially functionally graded design method using the lumped mass. In this investigation, the finite element method (FEM) is used to formulate the aeroelastic equation of motion for the panels with the lumped mass and spring constraint. For 2D panels with the lumped mass, the local mode coalescence is observed, and the influences of the weight and location of the lumped mass on the flutter stability and their mechanism are analyzed. The optimal ranges for the weight and location of the lumped mass are given out. For 2D panels with the spring constraint, the sudden decrease of the flutter bound due to the mode veering are analyzed, and an effective method to eliminate it by using the lumped mass is proposed. Finally, a structural optimization method based on the axially functionally graded design is proposed.