Determination of the region of the limiting states occurrence in RVS-20000 with the subsidence of the external bottom contour

The problem of the limiting states occurrence in the structures of a vertical steel tank is investigated in this work. To study the SSS of the metal structures of the object, the authors created a numerical model of the RVS-20000 tank in the ANSYS software complex. The model considers the maximum number of elements with their geometry and connections affecting the tank SSS under non-axisymmetric loading, including beyond the elasticity of steel. Dependences between the parameters of intrinsic stiffness of the VST are obtained. The results of the finite element analysis made it possible to develop a technique for assessing the technical condition of the structure with the development of irregular subsidence of the external bottom contour. The proposed technique can be used by both operating and design organizations in making managerial decisions regarding the repair of RVS-20000 subjected to the base subsidence.

Analysis of the stress-strain state of a tank in case of irregular subsidence along the periphery

In the article, the authors proposed a calculation model for determining the SSS of a vertical steel tank in case of irregular subsidence of the external bottom contour in accordance with the geometric parameters of a real RVS-20000 m3 tank. An experiment is planned and presented including a scheme with two influencing factors: the geometric model of the tank and the value of the dimensionless coefficient m. The influencing factors have 3 and 5 combinations respectively, which is represented in the experiment matrix. The article shows diagrams of displacements, stresses of the tank structures, and graphically depicts the dependences of the displacements of shells on the values of subsidence zones. The presence of a stiffening ring and a stationary roof provides the least values for vertical and horizontal displacements. Conclusions about the influence of the factors considered on the SSS of a tank in case of irregular subsidence of the external bottom contour are presented.

Study of Curve Planning Algorithm for Partition-Type Rotary Burrs

For traditional rotary burrs, cutter teeth converge at the vertex, which means small chip space and poor cutting condition. In order to increase the chip space and to improve the cutting condition, a new type of rotary burrs with partition blade teeth, which took the feasibility of the actual process into consideration, was proposed. The curve planning algorithm planned the blade curves on the tooth bottom contour surface, and adjusted the tooth bottom contour model by some parameters, such as the small central angle and the position of oblique planes, to control the contour and blade shape for rotary burrs effectively. Experimental results demonstrate the effectiveness of the proposed algorithm.

On the parabolic equation method for water-wave propagation

A parabolic approximation to the reduced wave equation is investigated for the propagation of periodic surface waves in shoaling water. The approximation is derived from splitting the wave field into transmitted and reflected components.In the case of an area with straight and parallel bottom contour lines, the asymptotic form of the solution for high frequencies is compared with the geometrical optics approximation.Two numerical solution techniques are applied to the propagation of an incident plane wave over a circular shoal.