Encurvadura confinada de placas retangulares

04/12/2023

In this dissertation, the analysis by the finite element method of thin plates under uniform membrane internal forces subjected to the buckling phenomenon considering the presence of unilateral point obstacles is addressed. Rectangular and square plates are analysed under various membrane uniform loadings, including compression and shear. Two types of finite elements, ACM and BFS, are employed to compute the bifurcation loads and instability modes in scenarios with and without unilateral obstacles. An appropriate algorithm was used to solve the complementarity problem of eigenvalues and eigenvectors, based on the extension of the Newton-Raphson method for nonlinear complementarity systems. For each plate and type of loading, the six lowest bifurcation loads, and corresponding modes are computed for different levels of mesh refinement. The dissertation confirmed that the convergence of bifurcation loads obtained using the BFS element is monotonically decreasing as the mesh is refined. In contrast, convergence is generally non-monotonic when using the non-conforming ACM element. It was also confirmed that, when unilateral obstacles are present the lowest bifurcation load, known as the critical load, can never be lower than the one of the homologous cases without unilateral obstacles.

Autores da comunidade :

• 

  J

  João Manuel Vasconcelos Magalhães Pereira de Figueiredo

  ist186870

Orientadores desta instituição:

• 

  A

  António Manuel Figueiredo Pinto da Costa

  ist12764

• 

  F

  Fernando Manuel Fernandes Simões

  ist12555

- Engenharia Civil

- Português

Instituto Superior Técnico