| Summary: | 碩士 === 國立臺灣大學 === 地質學研究所 === 88 === This thesis aims to identify the mechanisms associated with folding of a single visco-elastic layer based on a series of numerical analyses, using finite element program, ABAQUS. The factors, including material properties, strain rate as well as simulation skill were considered.
The analyzed results indicate that: (1) The waveform is dominated by the compressing rate, namely the strain rate. As the layer is compressed under fast strain rate the waveform of the yielded fold is dominated by the elastic competence contrast R, and has a critical wave length; (2) As the strain rate is slow, the waveform is controlled by the initial geometrical perturbation.
To exclude the influence of initial perturbation, this research develops a perturbation method without introducing the geometry imperfection. Again, when compressed under fast strain rate, the waveform is controlled by the elastic properties. When the applied force F is greater then a certain value , the waveform comprises of two frequencies. When F is less then a certain value , the waveform has only one frequency with decreasing amplitudes away from the perturbed end.
As the layer is two-stage compressed with a fast and a slow strain rates, we found the waveform yielded at initial stage with fast strain rate can be maintained to later stage regardless the slow strain rate. On the other hand, the waveform yielded at initial stage with slow strain rate can be altered by the later fast strain rate.
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