THREE-DIMENSIONAL ANALYSIS OF SANDWICH STRUCTURES BY BOUND-ARY ELEMENT METHOD

THREE-DIMENSIONAL ANALYSIS OF SANDWICH STRUCTURES BY BOUND-ARY ELEMENT METHOD

Almeida, F. P. A.; Filho, R. S. Romão

Full Article:

The development of new materials has become increasingly important in the growth of various industrial sectors, awakening the interest of the aeronautical, naval, auto-mobile, offshore, sports and civil engineering industries. These materials include composites, which if well designed, enable the best characteristics of their constituent parts to be exploit-ed. However, along with all of its benefits, such materials pose significant challenges when it comes to determining their mechanical properties. Thanks to advances in technology and the constant evolution of computers, these properties can be determined numerically through such methods as the Finite Element Method (FEM) and the Boundary Element Method (BEM), among others. This study seeks to determine the linear mechanical behaviour of het-erogeneous structures through computer simulations, using a three-dimensional BEM/BEM coupling formulation, where the sub-region technique is applied. Linear approximation for triangular boundary elements is also considered. The effective mechanical properties of the sandwich structures obtained by the Boundary Element Method and the Mixing Rule were compared, as well as the relationships between stiffness and weight in the sandwich struc-tures and in the homogeneous plates. In all of the analyzed cases, the percentage error be-tween the methods was found to be high, with some reaching over 50%. This can be attributed to the simplicity of the Mixing Rule, where the Poisson ratio of the constituent materials is not taken into consideration. In other words, the strains resulting from the Poisson effect are con-stant throughout the material. With respect to the study of the relationship between stiffness and weight in sandwich structures and in comparison with equivalent homogeneous struc-tures, it was found that in all of the cases, the thickness of the homogeneous material was lower than that of the composite material. Materials with metal foam (light aluminum) display a higher stiffness-to-weight ratio than the homogeneous plates. Those containing polyure-thane have the lowest stiffness-to-weight ratio.

The development of new materials has become increasingly important in the growth of various industrial sectors, awakening the interest of the aeronautical, naval, auto-mobile, offshore, sports and civil engineering industries. These materials include composites, which if well designed, enable the best characteristics of their constituent parts to be exploit-ed. However, along with all of its benefits, such materials pose significant challenges when it comes to determining their mechanical properties. Thanks to advances in technology and the constant evolution of computers, these properties can be determined numerically through such methods as the Finite Element Method (FEM) and the Boundary Element Method (BEM), among others. This study seeks to determine the linear mechanical behaviour of het-erogeneous structures through computer simulations, using a three-dimensional BEM/BEM coupling formulation, where the sub-region technique is applied. Linear approximation for triangular boundary elements is also considered. The effective mechanical properties of the sandwich structures obtained by the Boundary Element Method and the Mixing Rule were compared, as well as the relationships between stiffness and weight in the sandwich struc-tures and in the homogeneous plates. In all of the analyzed cases, the percentage error be-tween the methods was found to be high, with some reaching over 50%. This can be attributed to the simplicity of the Mixing Rule, where the Poisson ratio of the constituent materials is not taken into consideration. In other words, the strains resulting from the Poisson effect are con-stant throughout the material. With respect to the study of the relationship between stiffness and weight in sandwich structures and in comparison with equivalent homogeneous struc-tures, it was found that in all of the cases, the thickness of the homogeneous material was lower than that of the composite material. Materials with metal foam (light aluminum) display a higher stiffness-to-weight ratio than the homogeneous plates. Those containing polyure-thane have the lowest stiffness-to-weight ratio.

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DOI: 10.5151/meceng-wccm2012-18533

Referências bibliográficas

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Como citar:

Almeida, F. P. A.; Filho, R. S. Romão; "THREE-DIMENSIONAL ANALYSIS OF SANDWICH STRUCTURES BY BOUND-ARY ELEMENT METHOD", p-1737-1753. In: In Proceedings of the 10th World Congress on Computational Mechanics [= Blucher Mechanical Engineering Proceedings, v. 1, n. 1]. São Paulo: Blucher, 2014.
ISSN 23580828, DOI 10.5151/meceng-wccm2012-18533