Study On The Viscous-Spring Boundary And The Transmitting Boundary

For the dynamic analysis of some important complex structures such as high-rise,high dam, nuclear power station and so on, the wave propagation from structure intoinfinite foundation should be considered. The problem is huge for solution, and mayinclude mediums coupling, medium material nonlinearity and dynamic contactinterfaces etc. Therefore, an effective numerical method must be provided for thedynamic analysis of this large complex system. The combination method of theexplicit finite element method and the local artificial boundary is applicable to solutethe above complicated problem because of its uncoupling characteristic. In thedissertation, the studies on the viscous-spring boundary and the transmitting boundaryare carried out and some useful conclusions are achieved. In the dissertation, a kind of new calculation formulation of viscous-springboundary is proposed. Comparing with the existing viscous-spring boundaries, it hasadvantage as flowing: (1) the boundary model is simple and doesn't include the addedmass. (2) The boundary expressions include all medium material constant. (3) Themethod's accuracy is high. The numerical analysis of stability for transmitting boundary indicates that theexisting methods of control instability are experiential, be short of the objective basisof parameter choosen and affect the accuracy in some conditions. The analysis of accuracy indicates that the accuracy of viscous-spring boundaryin the dissertation correspond to that of second-order transmitting boundary. Theanalysis of effect of finite element model indicate: (1) when the different finiteelement models are used to analyze the same problem on the premise that theaccuracy of wave finite element is satisfied, the result of viscous-spring boundary fordifferent model is stabler than that of the transmitting boundary. (2) The analysis onwave problem with load outside finite field needs bigger boundary size than that withload inside finite field. The analysis of the local landform problem of hemisphere canyon and thecoupling problem of layered medium of fluid and solid indicate that the combination IIAbstractmethod of the explicit finite element method and the viscous-spring boundary iseffective.