Non-Stationary Division by the Space Time Finite Element Method in Vibration Analysis,
WYZSZA SZKOLA INZYNIERSKA ZIELONA GORA (POLAND) DEPT OF CIVIL ENGINEERING
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Commonly known methods of integration of the motion equation require the same partition of the structure into finite elements in each time step. The stiffness, mass and damping matrices formulated at the begining are valid throughout the whole time period of computations. If non-linear problems are considered the global matrix formulation is performed in each step. In plasticity problems for example the influence of the plastic regions is taken into account while element matrices are computed. Different functions are integrated in different parts of the element area. Also in teh case of a beam or a plate placed on the unilateral foundation the construction in each moment is described by different differential equations. If the partition is stationary the line which limits the area of the soil-structure contact does not coincide with the division mesh. It should be emphasized that in the static analysis the structure is divided into elements choosing characteristic points or some characteristic curves, for example in places were material properties or thickness are changed.