Abstract
This paper describes vibration analysis using finite element method with Model Strain Energy Method for elastic frames with a damped panel connected by nonlinear concentrated springs under impact load. The panel is composed of a steel panel with a damping material. Damping material is made of viscoelastic body. And the panel has a curved surface. Finite element for the nonlinear springs are expressed and are connected to the elastic frames with the panel modeled by linear solid finite elements in consideration of complex modulus of elasticity. The restoring force of the spring has cubic nonlinearity and linear hysteresis damping. We calculated Modal loss factors and transient responses including internal resonances in the eigen modes among the non-linear springs, the panel and the frame structure. The non-linear discretization equation is converted from physical coordinate to normal coordinate corresponding to linear natural modes. Using this method, the responses in the large-scale degrees of freedom problems, were analyzed at high speed. And the dominant eigen modes contained in responses are picked up. Calculations were performed on the curved panel and the flat panel. We compared the obtained results. From the dominant eigen modes and the time histories, we clarified effects of the damping materials, the curvature and non-linear springs on the nonlinear damped responses.
