Investigation on Snap-Through Buckling Behavior of Dished Shells Under Uniform External Pressure

2020 ◽  
Vol 87 (12) ◽  
Author(s):  
Surya Mani Tripathi ◽  
Digendranath Swain ◽  
R. Muthukumar ◽  
S. Anup
Keyword(s):  
Numerical Study ◽  
Plastic Material ◽  
External Pressure ◽  
Image Correlation ◽  
Geometrical Parameters ◽  
Imperfection Sensitivity ◽  
Value Analysis ◽  
Uniform External Pressure ◽  
Buckling Behavior ◽  
Non Linear

Abstract Previously, the buckling behavior of several conical and spherical shells have been studied with great rigor. In this paper, snap-through buckling behavior for metallic dished shells under uniform external pressure is investigated. These shells are geometrically complex since they consist of a shallow conical frustum with a flat closed top. Such shells find many engineering applications, for instance as actuator elements in control components in cryogenic engines. Currently, no clear guidelines exist for design performance evaluation of such peculiar shells. This paper aims to establish a valid FE methodology for snap-through buckling and post-buckling analysis of such shells using abaqus in tandem with experiments. A parametric study is carried out to understand the effect of geometrical parameters and imperfection sensitivity of these shells to snap-through buckling. Moreover, experiments were carried out using 3D Digital Image Correlation (3D-DIC) for measuring whole-field deflection and strains. Numerical analysis was carried out, using generalized Eigen value analysis and non-linear analysis using a modified-Riks technique with various material models to correlate with the experimental observations. Non-linear elasto-plastic analysis with a perfectly elastic-plastic material model agrees well with the experimental observations. A comparison of experimental results with that of the numerical study indicates that material plasticity has a major effect on critical buckling pressure.

scholarly journals Non-stationary extreme value analysis applied to seismic fragility assessment for nuclear safety analysis

2019 ◽  
Author(s):  
Jeremy Rohmer ◽  
Pierre Gehl ◽  
Marine Marcilhac-Fradin ◽  
Yves Guigueno ◽  
Nadia Rahni ◽  
...  
Keyword(s):  
Failure Probability ◽  
Linear Models ◽  
Extreme Value ◽  
Steam Line ◽  
Information Criteria ◽  
Extreme Value Analysis ◽  
Geometrical Parameters ◽  
Value Analysis ◽  
Gev Distribution ◽  
Non Linear

Abstract. Fragility curves (FC) are key tools for seismic probabilistic safety assessments that are performed at the level of the nuclear power plant (NPP). These statistical methods relate the probabilistic seismic hazard loading at the given site and the required performance of the NPP safety functions. In the present study, we investigate how the tools of non-stationary extreme value analysis can be used to model in a flexible manner the tail behaviour of the engineering demand parameter as a function of the considered intensity measure. We focus the analysis on the dynamic response of an anchored steam line and of a supporting structure under seismic solicitations. The failure criterion is linked to the exceedance of the maximum equivalent stress at a given location of the steam line. A series of three-component ground-motion records (~ 300) were applied at the base of the model to perform non-linear time history analyses. The set of numerical results was then used to derive a FC, which relates the failure probability to the variation of peak ground acceleration (PGA). The probabilistic model of the FC is selected via information criteria completed by diagnostics on the residuals, which support the choice of the generalized extreme value GEV distribution (instead of the widely used log-normal model). The GEV distribution is here non-stationary and the relationships of the GEV parameters (location, scale and shape) are established with respect to PGA using smooth non-linear models. The procedure is data-driven, which avoids the introduction of any a priori assumption on the shape/form of these relationships. To account for the uncertainties in the mechanical and geometrical parameters of the structures (elastic stiffness, damping, pipeline thicknesses, etc.), the FC is further constructed by integrating these uncertain parameters. A penalisation procedure is proposed to set to zero the variables of little influence in the smooth non-linear models. This enables us to outline which of these parametric uncertainties have negligible influence on the failure probability as well as the nature of the influence (linear, non-linear, decreasing, increasing, etc.) with respect to each of the GEV parameters.

Nonlinear Buckling Behavior of Cylindrical Shells of Uniform Thickness under Wind Load

2012 ◽  
Vol 594-597 ◽  
pp. 2753-2756
Author(s):  
Lei Chen ◽  
Yi Liang Peng ◽  
Li Wan ◽  
Hong Bo Li
Keyword(s):  
Cylindrical Shells ◽  
External Pressure ◽  
Pressure Vessels ◽  
Wind Pressure ◽  
Uniform Thickness ◽  
Nonlinear Buckling ◽  
Buckling Modes ◽  
Uniform External Pressure ◽  
Aspect Ratios ◽  
Buckling Behavior

Abstract: Cylindrical shells are widely used in civil engineering. Examples include cooling towers, nuclear containment vessels, metal silos and tanks for storage of bulk solids and liquids, and pressure vessels. Cylindrical shells subjected to non-uniform wind pressure display different buckling behaviours from those of cylinders under uniform external pressure. At different aspect ratios, quite complex buckling modes occur. The geometric nonlinearity may have a significant effect on the buckling behavior. This paper presents a widely study of the nonlinear buckling behavior of cylindrical shells of uniform thickness under wind loading. The finite element analyses indicate that for stocky cylinders, the nonlinear buckling modes are the circumferential compression buckling mode, which is similar to cylinders under uniform external pressure, while for cylinders in mediate length, pre-buckling ovalization of the cross-section has an important influence on the buckling strength.

scholarly journals Buckling of a Short Cylindrical Shell Surrounded by an Elastic Medium

1999 ◽  
Vol 67 (1) ◽  
pp. 212-214 ◽  
Author(s):  
S. Naili ◽  
C. Oddou
Keyword(s):  
Tube Wall ◽  
Surrounding Medium ◽  
External Pressure ◽  
Elastic Tube ◽  
Geometrical Parameters ◽  
Buckling Mode ◽  
Uniform External Pressure ◽  
Cylindrical Structure ◽  
Thin Tube ◽  
Theoretical Results

The lateral surface of a cylindrical structure, which is composed of a thin tube embedded in a large outer medium, is submitted to a uniform external pressure. The buckling pressure of such a structure, corresponding to a low flexural state of the inner tube wall, is theoretically analyzed on the basis of the asymptotic method. The theoretical results are compared with experimental ones obtained from a compression test realized on an elastic tube inserted in a foam. It is found that the Euler pressure and the associated buckling mode index strongly depend upon the rheological and geometrical parameters of both the tube and the surrounding medium. [S0021-8936(00)00201-4]

Buckling Behavior of General Dome Ends under External Pressure, Using Finite Element Analysis

2011 ◽  
Vol 471-472 ◽  
pp. 833-838 ◽  
Author(s):  
Behzad Abdi ◽  
Hamid Mozafari ◽  
Ayob Amran
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Major Axis ◽  
External Pressure ◽  
Geometrical Parameters ◽  
Element Analysis ◽  
Buckling Behavior ◽  
Ellipse Method ◽  
The Finite Element Analysis ◽  
Critical Buckling Pressure

In this paper, the finite element analysis is used to investigate the effect of shape of dome ends on the buckling of pressure vessel heads under external pressure. The Finite Element Analysis (FEA) with the use of elastic buckling analysis was applied to predict the critical buckling pressure. The influence of geometrical parameters such as thickness, knuckle radius, and the ratio of minor axis to the major axis of dome ends, on the weight and the critical buckling pressure of hemispherical, ellipsoidal, and torispherical dome ends, was studied. The four-centered ellipse method was used to describe the geometry of the dome end.

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