The Microstructure and Compressive Response of Closed-cell Aluminum Foam
|關鍵字:||封閉式泡沫材料;微觀結構;數值模擬;closed-cell foam;microstructure;FEM simulation|
|摘要:||本研究主要目的在以實驗及數值模擬方式探討 ALPORAS 封閉式泡沫鋁材料之微觀結構與其受壓力學響應。實驗方面，本研究採用微電腦斷層掃描方式，呈現ALPORAS泡沫鋁材料內部三維結構。利用三維影像重建技巧，量測材料內部包含細胞尺寸、細胞之表面積、細胞之幾何形狀、細胞寬高比與細胞圓球率等幾何特徵。另將材料結構分為支柱與細胞壁面，分別量測其彎曲之最大振幅。
The present study aims to investigate the microstructure and compressive response of ALPORAS closed-cell foam by means of both experimental and numerical efforts. Toward this end the micro-CT technique was first adopted to generate the three-dimensional representations of the interior structure of the foam from which the geometrical characteristics of the foam cellular microstructure, including the size, surface area, geometrical shape, aspect ratio, and sphericity of cells were measured. Also the struts and cell walls were separated from the material, so that the maximum amplitude of strut as well as cell wall curvatures can be evaluated. Based on the measured geometric features, Laguerre tessellation type numerical models were developed. The effects of geometric parameters such as probability density functions, sphere volume fraction, and coefficient of variation in sphere volume on the geometrical characteristics of the developed numerical models were examined. In addition, modified Laguerre numerical models were also developed by introducing additional geometric characteristics such as the strut curvature, the cell wall curvature, the cell wall variation and the missing cell walls. Numerical results revealed that the foam Young's modulus and the initiation stress decreased with increasing geometric characteristic factors. Finally both Laguerre as well as modified Laguerre modes were used to simulate the complete compressive response. While Laguerre and modified Laguerre models were capable of reproducing the deformation patterns and deformation revolutions observed in the crushing experiments, the modified Laguerre model outperformed the Laguerre model extensively as compared to the experimental results.
|Appears in Collections:||Thesis|