DYNAMIC CALCULATION OF THE BALL TANK UNDER THE ACTION OF LOADS AT THE SUPPORT SUBSIDENCE

The work is devoted to the study of stress-strain state (SSS) of a ball tank under the action of loads at support subsidence, to conducting static and dynamic calculation. The essence of the study is the development and verification of a tool for assessing the SSS of a ball tank under the action of dynamic and static loads.The aim of this study is to analyze the stress-strain state of the ball tank for storage of liquefied gases under the action of loads at the support subsidence with the modeling of remote sensing technology, conducting modal analysis of the structure and subsequent analysis of natural frequencies of  structure vibrations to prevent resonance.Objectives of the study: Creation and preparation for analysis by finite element method of the three-dimensional model built in ANSYS PC on the cloud of points obtained as a result of calculations in the simulation of laser survey in Microsoft Excel spreadsheet program; Conducting modal analysis of the ball tank, studying the natural frequencies of structural vibrations to prevent resonance, which may be caused by dynamic loads, under normal operating conditions; Modeling the support subsidence and roll of the tank, further analyzing the natural frequencies of structure vibration, and evaluating the effect of  the roll angle changing on the dynamic performance; Modal analysis for different filling levels (fully filled and half full tank).  The reasons causing non-uniform distribution of loads, negative consequences in case of coincidence of natural and external frequencies are considered, the relevance and necessity of the calculation in the program complex are substantiated.Modeling of support subsidence, tank roll is carried out in ANSYS software, calculations in which are based on the finite element method. The process of ball tank model creating is presented, as well as detailed instructions in the development of the model for modal analysis of various operating conditions that can cause changes in dynamic parameters.Based on modal analysis results it is revealed that the structure roll leads to a change in natural vibration frequency by no more than 1 %, and the support subsidence causes the emergence of new dangerous cases combining the two directions of the structure response. Analyzing the dependence of natural frequencies of vibrations on the level of tank filling, it is revealed that with the increase in the level of filling there is a decrease in the frequency of natural vibrations (from 3.0183 Hz in a full tank to 0.00043 Hz in a half full) and a change in the pattern of deformation distribution  in the structure.