非等向性岩層受拱彎褶皺之數值模擬初探
Date Issued
2004
Date
2004
Author(s)
吳方義
DOI
zh-TW
Abstract
The mechanics of folding has long been an important issue for those interested in structural geology. Although the theoretical model about the buckle of homogeneous isotropic materials has been established, few have concerned about anisotropic materials, which are more realistic. This thesis aims to study the buckle fold composed of anisotropic materials through numerical simulation.
This thesis uses ABAQUS developed by H.K.S. Inc., a finite element progrom, and the end-rotational method developed by Chang (1999). I constructed this model that is a two dimensional plane strain model, where the competent layer is surrounded by matrix, and the materials in this model are linear elastic. The factors, including material properties (degree of anisotropy, direction of the axis of symmetry of rotation… etc.), and boundary conditions were considered.
The relation between the force to buckle an isotropic elastic layer surrounded by matrix and its subsequent wavelength has been discussed. When the force is smaller than a critical value, the amplitude of the fold will be attenuated. On the contrary, the waveform comprises of two frequencies when the force is bigger than that critical value. The change of Young’s modulus in matrix in the direction normal to layer parallel shortening, and in competent layer in the direction of layer parallel shortening, affects waveform significantly. If we replace the Young’s modulus in the theoretical buckle formula by the Young’s modulus mentioned above, the theoretical formula fits the simulation results well. The largest strain elongation direction pattern corresponds to the description of folds with combined tangential longitudinal strain and layer parallel shear. The largest strain elongation directions are almost the same whether the models are comprised by isotropic or transversely isotropic material. But the aspect ratio R of the strain ellipse is affected by the anisotropy of material and the final waveform of the fold. The R of the transversely isotropic matrix model is larger than isotropic model if the final wave number of the two model are the same.
Subjects
褶皺
拱彎
非等向性
數值模擬
橫向等方性
anisotroy
transverse isotropy
buckle
folding
numerical simulation
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-93-R90224111-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):8a0af3267b8c1337bb3d212547f1b596