Dynamic Plastic Response of Cylindrical Shells Under Gaussian Impulse

1980 ◽  
Vol 24 (01) ◽  
pp. 24-30
Author(s):  
S. Anantha Ramu ◽  
K. J. Iyengar
Keyword(s):  
Cylindrical Shells ◽  
Yield Condition ◽  
Longitudinal Axis ◽  
Plastic Behavior ◽  
Plastic Response ◽  
Marine Structures ◽  
Impulsive Load ◽  
Tresca Yield Condition ◽  
Impulsive Loads

The determination of the inelastic response of cylindrical shells under general impulsive loads is of relevance to marine structures such as submarines, in analyzing their slamming damages. The present study is concerned with the plastic response of a simply supported cylindrical shell under a general axisymmetric impulsive load. The impulsive load is assumed to impart an axisymmetric velocity to the shell, with a Gaussian distribution along the longitudinal axis of the shell. A simplified Tresca yield condition is used. The shell response is determined for various forms of impulses ranging from a concentrated impulse to a uniform impulse over the entire length of the shell. Conclusions about the influence of geometry of the shell and the spatial distribution of impulse on the plastic behavior of cylindrical shells are presented.

The Influence of Rotatory Inertia and Transverse Shear on the Dynamic Plastic Behavior of Beams

1979 ◽  
Vol 46 (2) ◽  
pp. 303-310 ◽  
Author(s):  
Norman Jones ◽  
J. Gomes de Oliveira
Keyword(s):  
Transverse Shear ◽  
Shear Force ◽  
Yield Criterion ◽  
Yield Condition ◽  
Bending Moment ◽  
Plastic Behavior ◽  
Plastic Response ◽  
Rotatory Inertia ◽  
Perfectly Plastic ◽  
Theoretical Procedure

The theoretical procedure presented herein examines the influence of retaining the transverse shear force in the yield criterion and rotatory inertia on the dynamic plastic response of beams. Exact theoretical rigid perfectly plastic solutions are presented for a long beam impacted by a mass and a simply supported beam loaded impulsively. It transpires that rotatory inertia might play a small, but not negligible, role on the response of these beams. The results in the various figures indicate that the greatest departure from an analysis which neglects rotatory inertia but retains the influence of the bending moment and transverse shear force in the yield condition is approximately 11 percent for the particular range of parameters considered.

Elastic-Plastic Analysis of a Spherical Shell Loaded Radially Through a Flexible Cylindrical Nozzle

1990 ◽  
Vol 112 (3) ◽  
pp. 296-302 ◽  
Author(s):  
C.-P. Leung ◽  
G. N. Brooks
Keyword(s):  
Spherical Shell ◽  
Efficient Solution ◽  
Yield Condition ◽  
Geometric Parameters ◽  
Plastic Behavior ◽  
Elastic Plastic ◽  
Cylindrical Nozzle ◽  
Tresca Yield Condition ◽  
Failure Loads ◽  
Range Of Values

This study investigates the elastic-plastic behavior of a shallow spherical shell loaded radially through a flexible cylindrical nozzle. Both the sphere and the cylinder can yield and exhibit plastic deformation. The Tresca yield condition is employed to derive elastic-plastic moment-curvature relationship in a simple form which is implemented in an efficient solution scheme. Three geometric parameters represent the relative dimensions of the structure. Numerical results are obtained for a range of values of these parameters. Various situations involving the failure of the sphere and/or the cylinder are studied. The ultimate or failure loads of the structure are plotted as functions of the geometric parameters.

New method of determination of limit plastic load in intersecting cylindrical shells

2012 ◽  
Vol 48 (1-2) ◽  
pp. 15-21
Author(s):  
V. N. Skopinskii ◽  
N. A. Berkov ◽  
A. D. Emelyanova
Keyword(s):  
Cylindrical Shells ◽  
New Method ◽  
Method Of Determination

Experimental and Numerical Plastic Response and Failure of Laterally Impacted Rectangular Plates

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
B. Liu ◽  
R. Villavicencio ◽  
C. Guedes Soares
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Failure Modes ◽  
Mesh Size ◽  
Plastic Behavior ◽  
Finite Element Models ◽  
Rectangular Plates ◽  
Marine Structures ◽  
Fine Mesh ◽  
The Impact

Experimental and numerical results of drop weight impact test are presented on the plastic behavior and fracture of rectangular plates stuck laterally by a mass with a hemispherical indenter. Six specimens were tested in order to study the influence of the impact velocity and the diameter of the indenter. The impact scenarios could represent abnormal actions on marine structures, such as ship collision and grounding or dropped objects on deck structures. The tests are conducted on a fully instrumented impact tester machine. The obtained force-displacement response is compared with numerical simulations, performed by the LS-DYNA finite element solver. The simulations aim at proposing techniques for defining the material and restraints on finite element models which analyze the crashworthiness of marine structures. The mesh size and the critical failure strain are predicted by numerical simulations of the tensile tests used to obtain the mechanical properties of the material. The experimental boundary conditions are modeled in order to represent the reacting forces developed during the impact. The results show that the critical impact energy until failure is strongly sensitive to the diameter of the striker. The shape of the failure modes is well predicted by the finite element models when a relatively fine mesh is used. Comments on the process of initiation and propagation of fracture are presented.

Tables for Frequencies and Modes of Free Vibration of Infinitely Long Thin Cylindrical Shells

1954 ◽  
Vol 21 (2) ◽  
pp. 178-184
Author(s):  
M. L. Baron ◽  
H. H. Bleich
Keyword(s):  
Free Vibration ◽  
Poisson’S Ratio ◽  
Cylindrical Shells ◽  
Bending Stiffness ◽  
Poisson's Ratio ◽  
Underlying Theory ◽  
Half Wave ◽  
Quick Determination ◽  
Circumferential Waves

Abstract Tables are presented for the quick determination of the frequencies and shapes of modes of infinitely long thin cylindrical shells. To make the problem tractable, the shells are first treated as membranes without bending stiffness, and the bending effects are introduced subsequently as corrections. The underlying theory is based on the energy expressions for cylindrical shells. The tables cover the following range: lengths of longitudinal half wave L from 1 to 10 radii a; number n of circumferential waves from 0 to 6. The results apply for Poisson’s ratio ν = 0.30.

Application of Finite-Element Method to Interstiffener Buckling in Submersible Cylindrical Hulls

1983 ◽  
Vol 27 (04) ◽  
pp. 281-285
Author(s):  
K. Rajagopalan ◽  
C. Ganapathy Chettiar
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Computer Program ◽  
Cylindrical Shells ◽  
Geometric Stiffness ◽  
Stiffness Matrices ◽  
Finite Element Procedure ◽  
Stepwise Variation ◽  
Thin Walled

A finite-element procedure for the determination of buckling pressure of thin-walled cylindrical shells used in ocean structures is presented. The derivation of the elastic and geometric stiffness matrices is discussed in detail followed by a succinct description of the computer program developed by the authors during the course of this study for the determination of the buckling pressure. Particular attention is paid to the boundary conditions which strongly influence the buckling pressure. Applications involving the interstiffener buckling in submersible hulls and cylindrical shells with stepwise variation in wall thickness are considered and the results compared with the solutions and procedures available in the literature.

Influence of Rock Plastic Behavior on the Wellbore Stability

2021 ◽  
Author(s):  
Elena Grishko ◽  
Aboozar Garavand ◽  
Alexey Cheremisin
Keyword(s):  
Failure Criteria ◽  
Wellbore Stability ◽  
Standard Approach ◽  
Plastic Behavior ◽  
Element Formulation ◽  
Geomechanical Model ◽  
Plastic Properties ◽  
Plastic Deformations ◽  
3D Geomechanical Model

Abstract Currently, the standard approach to building a geomechanical model for analyzing wellbore stability involves taking into account only elastic deformations. This approach has shown its inconsistency in the design and drilling of wells passing through rocks with pronounced plastic properties. Such rocks are characterized by the fact that when the loads acting on them change, they demonstrate not only elastic, but also plastic (irreversible) deformations. Plastic deformations have an additional impact on the distribution of stresses in the rock of the near-wellbore zone on a qualitative and quantitative level. Since plastic deformations are not taken into account in the standard approach, in this case the results of the wellbore stability analysis are based on incorrectly calculated stresses acting in the rock. As a result, it can lead to misinterpretation of the model for analysis, suboptimal choice of trajectory, incorrect calculation of safe mud window and an incorrectly selected set of measures to reduce the risks of instability. The aim of this work is to demonstrate the advantages of the developed 3D elasto-plastic program for calculating the wellbore stability in comparison with the standard elastic method used in petroleum geomechanics. The central core of the work is the process of initialization of the elasto-plastic model according to the data of core tests and the subsequent validation of experimental and numerical loading curves. The developed 3D program is based on a modified Drucker-Prager model and implemented in a finite element formulation. 3D geomechanical model of wellbore stability allows describing deformation processes in the near-wellbore zone and includes the developed failure criteria. The paper shows a special approach to the determination of the mud window based on well logging data and core tests by taking into account the plastic behavior of rocks. An important result of this study is the determination of the possibility of expanding the mud window when taking into account the plastic criterion of rock failure.

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