PRINCIPLE OF VIRTUAL DISPLACEMENTS OF VISCOUS-SPRING ARTIFICIAL BOUDARIES

The paper takes the structure and near-field foundation as a dynamic equilibrium system and decomposes the input wave on artificial boundaries into free waves and dispersion waves that are mutually independent. Based on the above assumptions, the paper analyzes the dynamic equilibrium relation between the structure and near-field foundation and promulgation mechanism of free fields, deduces uniform expressions of the displacement, velocity and equipollent loads acting on artificial boundaries, and then sets up the dynamical integral week equations of viscous-spring artificial boundaries. Meanwhile, based on Finite Element Program Generator (FEPG), boundary element codes are developed for viscous-spring boundary conditions. Thus viscous-spring boundary conditions can be simply and rapidly applied like general displacements and stress conditions. The computational results show that element codes are accurate and reliable.