scholarly journals Plastic Deformation and Rupture of Ring-Stiffened Cylinders under Localized Pressure Pulse Loading

1994 ◽  
Vol 1 (3) ◽  
pp. 289-301 ◽  
Author(s):  
Michelle S. Hoo Fatt
Keyword(s):  
Plastic Deformation ◽  
Cylindrical Shell ◽  
Pressure Pulse ◽  
Fracture Initiation ◽  
Pulse Loading ◽  
Rigid Plastic ◽  
Stiffened Shell ◽  
Closed Form Solutions ◽  
Stiffened Cylindrical Shell ◽  
Lumped Masses

An analytical solution for the dynamic plastic deformation of a ring-stiffened cylindrical shell subject to high intensity pressure pulse loading is presented. By using an analogy between a cylindrical shell that undergoes large plastic deformation and a rigid-plastic string resting on a rigid-plastic foundation, one derives closed-form solutions for the transient and final deflection profiles and fracture initiation of the shell. Discrete masses' and springs are used to describe the ring stiffeners in the stiffened shell. The problem of finding the transient deflection profile of the central bay is reduced to solving an inhomogeneous wave equation with inhomogeneous boundary conditions using the method of eigenfunction expansion. The overall deflection profile consists of both global (stiffener) and local (bay) components. This division of the shell deflection profile reveals a complex interplay between the motions of the stiffener and the bay. Furthermore, a parametric study on a ring-stiffened shell damaged by a succession of underwater explosions shows that the string-on-foundation model with ring stiffeners described by lumped masses and springs is a promising method of analyzing the structure.

Rigid-Plastic Deformation of a Ring-Stiffened Shell Under Blast Loading

1997 ◽  
Vol 119 (4) ◽  
pp. 467-474 ◽  
Author(s):  
M. S. Hoo Fatt
Keyword(s):  
Plastic Deformation ◽  
Cylindrical Shell ◽  
Structural Model ◽  
Dynamic Equilibrium ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
Body Motion ◽  
Fine Tuning ◽  
Rigid Plastic ◽  
Stiffened Cylindrical Shell

An approximate solution for the plastic deformation of a ring-stiffened cylindrical shell in response to a nonaxisymmetric, exponentially decaying pressure load, is presented. The analogy between the ring-stiffened cylindrical shell and a rigid-plastic string-on-foundation with discrete plastic resisting elements is used to find closed-form solutions for the transient and final deformations of the shell. Dynamic equilibrium of the central bay of the shell and the adjacent ring-stiffeners results in an inhomogeneous wave equation with inhomogeneous boundary conditions for the string. The initial-boundary value problem is solved by the method of eigenfunction expansion and a suitable orthogonality condition. The zeroth mode for the string describes rigid-body motion of the bay due to the remaining inertia of adjacent stiffeners. Permanent deformations are obtained using a plastic unloading criterion whereby the velocity and strain rate for each eigenmode vanish simultaneously. In the example problem, higher eigenmodes decay and vanish rapidly and final shell deformations are primarily governed by lower eigenmodes. The structural model gives qualitatively correct transient deflections and would be amenable to fine-tuning with numerical analysis and experimental evidence.

scholarly journals Rigid-Plastic Approximations for Predicting Plastic Deformation of Cylindrical Shells Subject to Dynamic Loading

1996 ◽  
Vol 3 (3) ◽  
pp. 169-181 ◽  
Author(s):  
Michelle S. Hoo Fatt ◽  
Tomasz Wierzbicki ◽  
Minos Moussouros ◽  
John Koenig
Keyword(s):  
Plastic Deformation ◽  
Tensile Force ◽  
Bending Moment ◽  
Expansion Method ◽  
Rigid Plastic ◽  
Closed Form Solutions ◽  
Eigenfunction Expansion Method ◽  
Longitudinal Bending ◽  
Final Deformation ◽  
String State

A theoretical approach was developed for predicting the plastic deformation of a cylindrical shell subject to asymmetric dynamic loads. The plastic deformation of the leading generator of the shell is found by solving for the transverse deflections of a rigid-plastic beam/string-on-foundation. The axial bending moment and tensile force in the beam/string are equivalent to the longitudinal bending moments and membrane forces of the shell, while the plastic foundation force is equivalent to the shell circumferential bending moment and membrane resistances. Closed-form solutions for the transient and final deformation profile of an impulsive loaded shell when it is in a “string” state were derived using the eigenfunction expansion method. These results were compared to DYNA 3D predictions. The analytical predictions of the transient shell and final centerline deflections were within 25% of the DYNA 3D results.

Study of the Titanium Alloy Deformation Behavior in Equal Channel Angular Extrusion

2007 ◽  
Vol 345-346 ◽  
pp. 177-180 ◽  
Author(s):  
Dyi Cheng Chen ◽  
Yi Ju Li ◽  
Gow Yi Tzou
Keyword(s):  
Plastic Deformation ◽  
Titanium Alloy ◽  
Deformation Behavior ◽  
Equal Channel Angular Extrusion ◽  
Effective Strain ◽  
Processing Conditions ◽  
Rigid Plastic ◽  
Die Geometry ◽  
Extrusion Processing ◽  
Plastic Deformation Behavior

The shear plastic deformation behavior of a material during equal channel angular (ECA) extrusion is governed primarily by the die geometry, the material properties, and the processing conditions. Using commercial DEFORMTM 2D rigid-plastic finite element code, this study investigates the plastic deformation behavior of Ti-6Al-4V titanium alloy during 1- and 2-turn ECA extrusion processing in dies containing right-angle turns. The simulations investigate the distributions of the billet mesh, effective stress and effective strain under various processing conditions. The respective influences of the channel curvatures in the inner and outer regions of the channel corner are systematically examined. The numerical results provide valuable insights into the shear plastic deformation behavior of Ti-6Al-4V titanium alloy during ECA extrusion.

Analyses of Full-Scale Tank Car Shell Impact Tests

2007 ◽  
Author(s):  
Y. H. Tang ◽  
H. Yu ◽  
J. E. Gordon ◽  
M. Priante ◽  
D. Y. Jeong ◽  
...  
Keyword(s):  
Finite Element ◽  
Test Data ◽  
Three Dimensional ◽  
Full Scale ◽  
Collision Dynamics ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Rigid Plastic ◽  
Element Analysis ◽  
Closed Form Solutions

This paper describes analyses of a railroad tank car impacted at its side by a ram car with a rigid punch. This generalized collision, referred to as a shell impact, is examined using nonlinear (i.e., elastic-plastic) finite element analysis (FEA) and three-dimensional (3-D) collision dynamics modeling. Moreover, the analysis results are compared to full-scale test data to validate the models. Commercial software packages are used to carry out the nonlinear FEA (ABAQUS and LS-DYNA) and the 3-D collision dynamics analysis (ADAMS). Model results from the two finite element codes are compared to verify the analysis methodology. Results from static, nonlinear FEA are compared to closed-form solutions based on rigid-plastic collapse for additional verification of the analysis. Results from dynamic, nonlinear FEA are compared to data obtained from full-scale tests to validate the analysis. The collision dynamics model is calibrated using test data. While the nonlinear FEA requires high computational times, the collision dynamics model calculates gross behavior of the colliding cars in times that are several orders of magnitude less than the FEA models.

scholarly journals Strain Growth in a Finite-Length Cylindrical Shell Under Internal Pressure Pulse

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Qi Dong ◽  
Q. M. Li ◽  
Jinyang Zheng
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Internal Pressure ◽  
Finite Length ◽  
Pressure Pulse ◽  
Elastic Response ◽  
Local Dynamic ◽  
Growth Phenomenon ◽  
Modal Coupling ◽  
Elastic Responses

Strain growth is a phenomenon observed in the elastic response of containment vessels subjected to internal blast loading. The local dynamic response of a containment vessel may become larger in a later stage than its response in the earlier stage. In order to understand the possible mechanisms of the strain growth phenomenon in a cylindrical vessel, dynamic elastic responses of a finite-length cylindrical shell with different boundary conditions subjected to internal pressure pulse are studied by finite-element simulation using LS-DYNA. It is found that the strain growth in a finite-length cylindrical shell with sliding–sliding boundary conditions is caused by nonlinear modal coupling. Strain growth in a finite-length cylindrical shell with free–free or simply supported boundary conditions is primarily caused by the linear modal superposition, possibly enhanced by the nonlinear modal coupling. The understanding of these strain growth mechanisms can guide the design of cylindrical containment vessels.

Laminated Composite Stiffened Cylindrical Shell Panels with Cutouts under Free Vibration

2015 ◽  
Vol 5 (3) ◽  
pp. 37-63 ◽  
Author(s):  
Sarmila Sahoo
Keyword(s):  
Cylindrical Shell ◽  
Free Vibration ◽  
Laminated Composite ◽  
Beam Element ◽  
Benchmark Problems ◽  
Finite Element Code ◽  
Optimum Size ◽  
Isoparametric Element ◽  
Stiffened Cylindrical Shell ◽  
Practical Constraints

The free vibration of laminated composite stiffened cylindrical shell panels in the presence of cutout is investigated. A finite element code is developed using eight-noded curved quadratic isoparametric element for shell with a three noded beam element for stiffener and the formulation is validated through solution of benchmark problems which were earlier solved by other researchers. Parametric study is carried out varying the size of the cutouts and their positions with respect to the shell centre for different edge constraints. The results are presented in the form of figures and tables. The results are further analyzed to suggest guidelines to select optimum size and position of the cutout with respect to shell centre considering the different practical constraints.

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