Dynamic study of gaps-structures subjected to random excitation

The nonlinear mechanic gaps-structures on motion are frequent in industrial constructions. Their movement is particularly complex when the excitation is a white noise process. After a modelization discussion of the problem and recalling principal mathematical definitions in the first chapter, we have shown in the second one the limits of stochastic modelization in the stationary case. We propose then a synthetic studies on numerical simulation of nonlinear gaps-structures in the third chapter, when an algorithm based on modal decomposition and Markov integration technique is kept. The study of movement of mechanic gaps-structures with numerical simulation technique show that the spectral response for white noise excitation have a linear multi-modal spectral response characteristic. In sense to linearized this response and to respect this character, a spectral linearization technic based on ARMA processes is developed in the fourth chapter. The originality of this technique is to find a linear equivalent mechanic system for nonlinear gap-oscillator. It's the aim of the second part of the same chapter. The fifth chapter is consecrated to many applications (nonlinear oscillator and multi-degrees of freedom structures) of spectral linearization and a linear equivalent mechanics systems are found. (author)