Caracterização experimental de sistemas mecânicos com comportamento não-linear

• Ano de defesa: 2015
• Autor(a) principal: Hansen, Cristian [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Sistemas não lineares; Monitoramento da integridade estrutural; Volterra, Equações de; Nonlinear systems
• Link de acesso: http://hdl.handle.net/11449/134107; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/14-01-2016/000857604.pdf

A large number of structural engineering designs are seeking for more economic concepts, which leads to lightweight and flexible structures. These structures have nonlinear beha- vior caused by large deformations. In that case, it is need to use models that include a mathematical function to represent the possible nonlinear behavior. The first step to find a model to describe the nonlinearities is to identify the presence of some nonlinear mechanisms, as for instance, jump, multi-harmonics, modal interactions etc. The Vol- terra series are introduced and used as tool on identification of nonlinear systems. After that, Volterra models are used on detection of structural changes on mechanical systems with inherent nonlinear behavior (in the healthy condition). This technique is based on identification of the Volterra kernels expanded in an orthonormal Kautz basis. The Volterra kernels are used to filter the linear and nonlinear contributions. To illustrate the results, several experimental tests are performed in three test rigs which simulate nonlinear behavior, both, hardening and softening. The excitations signals are applied with different amplitude levels to observe the non-linear vibration behavior. Structural changes are simulated in the systems by loads or magnetic coupling. The results obtained allow us to show the effectiveness of Volterra series for detection of structural changes and quantification of nonlinear behavior on nonlinear mechanical systems