Study on experimental estimation of characteristics of nonlinear vibration with a gap under random vibration

This paper deals with evaluation of nonlinear vibration specific characteristic of a continuous body with a gap under stationary random input waves by experiments. The experimental model is a fixed beam with both ends which has mass on the center and a thin plate fixed with both ends with a gap between the mass and the plate. It was found that the form of a transfer function when the mass is colliding with the plate is the form with one large peak. If the collision is begun, the dominant frequency become larger than the eigen-frequency. Furthermore if the input acceleration becomes large, the dominant frequency changes to the larger one. If the collision is begun, equivalent damping ratio becomes large. When the input acceleration becomes large, the equivalent damping ratio becomes large and becomes to vary around a constant value. The probability density for peak magnitude of displacement (PDPMD) is expressed as the Rayleigh distribution, when not colliding. It was found that PDPMD is expressed in a sum of the Rayleigh distribution and the normal distribution approximately, when colliding. (author)