1D HERMITE ELEMENTS FOR C<sup>1</sup>-CONTINUOUS SOLUTIONS IN SECOND GRADIENT ELASTICITY

Authors

  • Christian Liebold Berlin University of Technology, Chair of Continuum Mechanics and Materials Theory, Einsteinufer 5, 10587 Berlin, Germany
  • Wolfgang H. Müller Berlin University of Technology, Chair of Continuum Mechanics and Materials Theory, Einsteinufer 5, 10587 Berlin, Germany

DOI:

https://doi.org/10.14311/APP.2017.7.0033

Abstract

We present a modified strain gradient theory of elasticity for linear isotropic materials in order to account for the so-called size effect. Additional material length scale parameters are introduced and the problem of static beam bending is analyzed. A numerical solution is derived by means of a finite element approach. A global C1-continuous displacement field is applied in finite element solutions because the higher-order strain energy density additionally depends on second gradients of displacements. So-called Hermite finite elements are used that allow for merging gradients between elements. The element stiffness matrix as well as the global stiffness matrix of the problem is developed. Convergence, C1-continuity and the size effect in the numerical solution is shown. Experiments on bending stiffnesses of different sized micro beams made of the polymer SU-8 are performed by using an atomic force microscope and the results are compared to the numerical solution.

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Published

2016-12-09

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Articles