Behavior Of Cylindrical Structures Research Articles

A Study of the hydrodynamic behavior of cylindrical structure with double porous outer shelters

Porous structure can effectively reduce the loads caused by the water wave, which results in lowering the cost of engineering project. The double porous shelter performs even better. Therefore, it receives much attention from researches. However, most of the previous studies dealing with the analysis of the interaction between water wave are porous structure were based on two-dimensional plane wave assumption. This can hardly reflect the real phenomena of complex wave action. In this paper, a semi-analytical solution to the hydrodynamic interaction between the three-dimensional short-crested wave and the cylindrical structure with double porous shelters is performed by employing the scaled boundary finite element method (SBFEM). The SBFEM possesses the advantages of finite element method (FEM) and boundary element method (BEM): the spatial dimension of the problem is reduced by one, no fundamental solution is needed and no singularity occurs. Meanwhile, this method can meet the infinity of the boundary condition automatically. In the SBFEM, the total computational domain is divided into three sub-domains, two ring-shaped finite sub-domains and one outer infinite sub-domain. A variational principle approach is proposed to establish the SBFE governing equations, which describe the variation of the velocity potential of wave motion in the radial direction. Bessel functions and Hankel functions are chosen as the basis functions for the solution of bounded and unbounded sub-domain problems, respectively. Numerical examples show that the proposed approach achieves very high accuracy and converges rapidly with quite few discretized nodes at the outer boundary. In comparison with the cylindrical structure with single porous shelter, the former performs better for the reduction of the water wave force. In addition, The influences of the wave parameters and the configuration of the structure on the system hydrodynamics, including the wave force, wave and diffracted wave contour are extensively examined. This research provides a valuable insight into the hydrodynamic analysis of cylindrical structure with double porous shelters and their structural design.

Thermal Ratcheting Behavior of a Cylindrical Structure with Plate-to-Shell Junction

In this study the progressive inelastic deformation behavior of the 316L stainless steel cylindrical structure with plate-to-shell weld junction under cyclic thermal loads was carried out by structural test and analysis. This structural test intends to simulate the thermal ratcheting behavior occurring at the thermal liner of the liquid metal reactor as free surface of hot sodium pool moves up and down under plant heat-up, cool down and other thermal transients. A thermal ratchet load that heats the cylindrical structure up to 550°C was applied cyclically and residual deformation was measured. The temperature distribution of the test specimen along the axial direction was measured and was used for the ratcheting analysis. The thermal ratchet deformations were analyzed with the constitutive equation of the non-linear combined hardening model and the analysis results were compared with those of the test. The ratcheting deformations for different plate thickness in plate-to-shell junction and different traveling lengths obtained by the analysis using the combined hardening model were in reasonable agreement with those of the structural tests.

Inelastic Behavior of Finite Circular Cylindrical Shells

In the design of elevated temperature components such as those encountered in Liquid Metal Fast Breeder Reactor (LMFBR) service, the designer/analyst is often faced with the task of having to assess structural adequacy of pressure vessel and piping components which experience high cyclic thermal stresses. Expensive and time consuming detailed inelastic analyses using finite element techniques are often necessary for such an assessment. Experience with the design of the LMFBR components has focused on an urgent need for simplified inelastic analysis methods which can aid the designer/analyst in scoping the design and minimize the number of parts requiring detailed inelastic analysis. Through its participation in the FFTF (Fast Flux Test Facility) and CRBRP (Clinch River Breeder Reactor Plant), Foster Wheeler Energy Corporation has developed a series of simplified analysis computer programs. The underlying philosophy in this work has been to make simplifying assumptions on the structural model but to solve the resulting boundary value problem as exactly as practicable so that approximations in the stress state or constitutive equations are not introduced. This paper is the third in a series [1, 11] by the authors dealing with the elastic-plastic-creep behavior of cylindrical structures. A rate formulation is presented for the elastic-plastic-creep analysis of finite circular cylindrical shells with various end conditions subjected to varying axisymmetric pressure loads, through-the-wall and along-the-length temperature gradients, and either axial loads or axial deformations. The solution procedure is based on direct integration and successive approximation and shown to be efficient in dealing with complicated loading histories. Applications of the present method of analysis are illustrated by numerical examples of elevated temperature design problem.