Abstract
This paper deals with nonlinear transient vibration analysis using finite element method for boxy structures made by six rectangular elastic plates supported by nonlinear springs. The bottom panel in the boxy structure is stiffened by beads. On the bottom plate, a viscoelastic damping material is laminated. The bottom plate is supported by four nonlinear concentrated springs near the four corners of this plate. The shape of the other five elastic plates is flat rectangle. The restoring force of the springs has cubic nonlinear terms and linear hysteresis damping. Finite elements for the nonlinear springs are expressed and are connected to the boxy structure modeled by linear solid finite elements. Further, the discretized equations in physical coordinate are transformed into the nonlinear ordinary coupled equations using normal coordinate corresponding to linear natural modes. Comparing shares of strain energy of the elastic plates, the damping layer and the springs, we investigate the influences of the bottom panel with/without the beads on modal loss factor. Furthermore, we evaluate the influences of the damping couplings on nonlinear transient responses by the differences of the bottom plate in the boxy structure.
