Showing papers by "Yiu-Yin Lee published in 2008"
TL;DR: In this paper, an improved IEFG method for two-dimensional elasticity is derived, where the orthogonal function system with a weight function is used as the basis function.
Abstract: This paper presents an improved moving least-squares (IMLS) approximation in which the orthogonal function system with a weight function is used as the basis function. The IMLS approximation has greater computational efficiency and precision than the existing moving least-squares (MLS) approximation, and does not lead to an ill-conditioned system of equations. By combining the element-free Galerkin (EFG) method and the IMLS approximation, an improved element-free Galerkin (IEFG) method for two-dimensional elasticity is derived. There are fewer coefficients in the IMLS approximation than in the MLS approximation, and in the IEFG method that is formed with the IMLS approximation fewer nodes are selected in the entire domain than are selected in the conventional EFG method. Hence, the IEFG method should result in a higher computing speed. For two-dimensional fracture problems, the enriched basis function is used at the tip of the crack to give an enriched IEFG method. When the enriched IEFG method is used, the singularity of the stresses at the tip of the crack can be shown better than that in the IEFG method. To provide a demonstration, numerical examples are solved using the IEFG method and the enriched IEFG method.
116 citations
TL;DR: In this article, a mixed finite element and classical formulation for the nonlinear multimodal structural acoustic interaction of a composite plate backed by a three dimensional cavity was developed by adopting the non-linear finite element modal reduction method for the two-dimensional plate and the classical solution for the three-dimensional acoustic cavity, respectively.
Abstract: This study aims to develop a mixed finite element and classical formulation for the nonlinear multimodal structural acoustic interaction of a composite plate backed by a three dimensional cavity. The formulation is developed by adopting the nonlinear finite element modal reduction method for the two-dimensional plate and the classical solution for the three-dimensional acoustic cavity, respectively. The main advantages of the adopted approach are as follows. 1) There is no need to update the nonlinear matrices; 2) the sizes of the nonlinear matrices can be reduced drastically; and 3) the acoustic pressure that acts on the plate can be obtained from the classical solution of the three-dimensional wave equation (i.e., no boundary element is required). Hence, the proposed approach can avoid the numerical error induced from the coupling between the two dimensional finite elements and three dimensional boundary elements. The frequency ratios for the fundamental modes of the structural-acoustic system at various plate vibration amplitudes, the contribution of each linear mode to the overall plate vibration, and the effect of air cavity depth on the frequency ratios are also studied.
9 citations
TL;DR: In this article, a probabilistic approach is introduced and used to distinguish between the interior pressures that are induced from two independent sound sources within a rectangular room, one source is a vibrating wall of the room and the other is an interior point source.
4 citations
TL;DR: Lee et al. as mentioned in this paper presented a full-scale experiment to identify the sound leakages on a wall of an enclosed room using the probabilistic approach, which is an unknown parameter in the identification process.
3 citations
TL;DR: In this article, the authors present the first full-scale experiment to verify the effectiveness of the probabilistic approach to distinguish between the interior pressures that are induced from independent sources within a room.