Finite Element Analysis of High Pressure Storage Tank

ICS solar systems with horizontal cylindrical storage tank and reflector of CPC or involute geometry

Based on the principle of axial active magnetic bearing system with single degree of freedom, the difference between magnetic system vibration mode and the traditional bearing system vibration mode were described. Initial four order natural frequencies and vibration mode were calculated by the module of modal analysis of ANSYS11. Axial displacement and control current influence on natural frequencies and vibration mode were also analyzed. At last they were compared with the results of experimental modal analysis. Analysis shows that there was a certain difference between the results of finite element method and experimental model analysis, but the difference was small. It provided theoretical basis for flexible system design and dynamic design.

The floating roofs are widely used to prevent evaporation of content in the large oil storage tanks. The 2003 Tokachi-Oki earthquake caused severe damage to the floating roofs due to liquid sloshing. The structural integrity of the floating roofs for the sloshing is urgent issue to establish in the petrochemical and oil refining industries. This paper presents the sloshing characteristics of single deck floating roofs in cylindrical storage tanks. The hydrodynamic coupling of fluid and floating roof is taken into consideration in the axisymmetric finite element analysis. It is assumed that the fluid is incompressible and inviscid, and the roof is linear elastic while the sidewall and the bottom are rigid. The basic vibration characteristics, natural periods and vibration modes, of the floating roof due to the sloshing are investigated. These will give engineers important information on the floating roof design.

With constant development of machine tools toward the direction of high speed, high precision, high efficiency and high compound rapidly. The performance of high-speed machine tools is affected by the dynamic characteristic of machine tools in the very great degree. More and more attention is played to them and higher and higher demands are proposed. Finite element method is a kind of fast and efficient auxiliary tools in modern engineering analysis and design. Three-dimensional finite element model of spindle box is established in this paper based on large finite element analysis software ANSYS. Through modal analysis, the first five order natural frequency, vibration mode and various order vibrating modal characteristics are obtained. These results are verified by using the method of experimental modal. Harmonic response analysis is carried after doing modal analysis on spindle box. Response and stress under different frequency are obtained. Continuous dynamic characteristics are forecasted.

According to the actual needs of rehabilitation training after knee joint replacement surgery, and based on ergonomics, the idea of personification design and the basic design idea of force transfer between human body and exoskeleton are discussed, objective to develop a rehabilitation exoskeleton robot for leg rehabilitation after knee joint replacement surgery. The robot can detect the movement trend of the human body, judge the motion intention in use, and promote the movement of the hind leg, so as to achieve the purpose of rehabilitation training of the knee joint. The modal analysis of the lower limb rehabilitation exoskeleton robot is carried out, and the first six order natural frequencies and vibration modes are obtained.

Damage reports from 11 different earthquakes are summarized in tabular format for typical oil refinery structures, such as cylindrical and spherical storage tanks, tall columns and chimneys, heat exchangers, pumps, and pipes. Information included herein is limited to damage caused by direct ground-motion effects. These data reveal that the most vulnerable refinery structure is the cylindrical storage tank. Other structures, such as distilling towers and pipes, are only occasionally damaged, and rarely is this damage severe. The consequences of these rare events, however, can be very costly when they involve fires.

Fluid sloshing hydrodynamics in a cryogenic fuel storage tank under different order natural frequencies

A novel compliant mechanism with three degree of freedom (DOF) is proposed, based on the method of Freedom and Constraint Topology (FACT). One movement and two rotations are obtained in Case 3, Type 2 freedom space. A redundant constraint is added to improve the symmetry. The finite element modal (FEM) is established and static force analysis is conducted. Results demonstrate that the compliant mechanism is decoupled. Modal analysis is carried out with the finite element method. And four orders natural frequency and main vibration mode are obtained.

This paper describes the vibration tests, in which sinusoidal wave excitations with large input are conducted to the scale model tank of a thin-walled cylindrical water storage tank, and the theoretical analysis on the vibratory behaviours which are observed during the vibration tests. Large input excitation tests are carried out, in which the test tank is excited intensively by sinusoidal waves of a resonance frequency. The response of the tank, which means beamtype vibration, is not excited in proportion to the input acceleration above a certain level. Since oval-type vibrations largely appear on the sidewall of the tank in the tests, the interaction of oval-type vibrations over beam-type vibrations is considered. Concerning the deformation of the sidewall of tank by the oval-type vibrations, it is found that a large decrease in the flexural rigidity reduces the response of beam-type vibrations. A nonlinear vibration model is proposed assuming the flexural rigidity depends on the amplitude of oval-type vibrations. The analysis using this model has a good agreement with the results of the tests. Thus, it is demonstrated both empirically and analytically that the response of beam-type vibrations is reduced and the resonance frequency of beam-type vibrations is lowered by the coupling with oval-type vibrations.

Cylindrical steel storage tanks are more vulnerable to local buckling when subjected to external pressure, axial loading, or lateral ground motion.This paper presents the static and seismic nonlinear analysis of empty shell and liquid-filled (83.4%) steel storage tanks using finite element analysis (FEA) commercial software ABAQUS.Firstly, to substantiate the accuracy of FEA, a perfect cylindrical specimen is considered for buckling analysis.Based on this study, the cylindrical steel storage tank is seismically excited in the horizontal direction under two real-world ground motions (Friuli 1974 and Northridge 1994 earthquake).Initially, the tank is subjected to the gravity load and hydrostatic nonlinear analysis in steps 1 and 2 for 1 second each.Then the dynamic implicit analysis is carried out for 20 and 30 seconds in each case to evaluate the seismic behavior of the storage tank.The results from static analysis show that the FEA buckling pressure is closely matched with the test and theoretical solution.Furthermore, from the parametric study, Nonlinear analysis shows that the maximum von Mises and hoop stresses are more dominant near the tank base.The response acceleration, distribution of the stresses including longitudinal and circumferential (hoop) stresses, and maximum pressure vs time response are evaluated.The results from seismic nonlinear analysis indicate that the tank experienced a maximum acceleration response when subjected to the Friuli earthquake which is slightly higher than the tank's response under the Northridge earthquake.Furthermore, the response shows that maximum excitation is in the lateral direction (x-component) where the ground motion is applied at the storage tank's base.The other components (y and zcomponents) do not significantly affect the tank's seismic performance.it can also be seen that the response in Z-direction is almost negligible.In case of the Northridge input excitation, the x-component represents the maximum response of the tank and the remaining components (y and z-components) does not have significant contribution in the tank excitations.Lastly, the pressure response shows that the tank under Friuli seismic excitation has a maximum peak compared to the tank subjected to the Northridge earthquake.

Aiming at the lightweight design of a vehicle-mounted radar array structure, the static analysis and modal analysis of the design model were carried out by Ansys to obtain the deformation, stress distribution cloud diagram and the first 6 order natural frequencies and modes of vibration. The calculation results show that the safety factor of each part of the radar array structure is above 2 and the maximum deformation is less than 20mm after the main array plate weight is reduced by 8%. The overall stiffness and strength of the radar array structure are good, which can meet the design requirements.

Coupled vibration analysis of liquid-filled rigid cylindrical storage tank with an annular plate cover

It is important in the confirmation of the safety of the nuclear power plant to clarify the response behavior of a vertical cylindrical water storage tank under seismic motion. When a vertical cylindrical tank is shaken by a large earthquake, deformation of side shell due to the elephant foot buckling, the oval vibration etc. may occur. The occurrence of those deformations depends on materials, shapes, stored water level and time history of seismic motion. Then, response behavior was obtained for a condensate storage tank (CST) model under large seismic motion such as standard earthquake Ss multiplied by 2 with the elastic-plastic finite element calculation. In this calculation, dynamic water pressure and elastic-plastic characteristics of the material were taken into account. In this case, the elephant foot bulge did not occur but the oval vibration of side shell became dominant. Based on the result, we estimated the structural integrity of the tank.

Based on the principle of axial active magnetic bearing rotor-system with single degree of freedom, magnetic rotor-system vibration mode was described. A 3D finite element model of active magnetic bearing rotor-system was established by ANSYS11. Initial six order natural frequencies and vibration mode were calculated by the module of modal analysis of ANSYS11, and compared with the results of system identification. Analysis shows that there was a certain difference between the results, but the difference was small. The analysis result indicates that it is an effective method to apply FEA in the design of the active magnetic bearing. It provided the foundation for structure optimal design of the system and theoretical basis for flexible system design.

In order to study the superposition effect of physical explosion and chemical explosion shock wave of liquefied natural gas storage tank and obtain the distribution law of load and overpressure, this paper uses ANSYS/LSDYNA to establish the finite element model and conduct numerical simulation calculation. The results show that the overpressure decreases with the increase of the circumferential angle in the shock wave superimposed region. As the surface of the storage tank increases in the addition of shock waves, its explosive load decreases gradually as the rearward Angle increases. As the height increases, the explosive load decreases first, then increases and then decreases. The overpressure time history curve of each point on the cylindrical storage tank is affected by the superposition of shock wave, reflection and diffraction of superimposed shock wave, and the peak overpressure in front of the device is slightly higher than that in the rear.