Closed-form aftershock reliability of damage-cumulating elastic-perfectly-plastic systems

2013 ◽  
Vol 43 (4) ◽  
pp. 613-625 ◽  
Author(s):  
Iunio Iervolino ◽  
Massimiliano Giorgio ◽  
Eugenio Chioccarelli
Keyword(s):  
Closed Form ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Closed-Form Plastic Collapse Loads of Pipe Bends Under Combined Pressure and In-Plane Bending

2006 ◽  
Author(s):  
Chang-Sik Oh ◽  
Yun-Jae Kim
Keyword(s):  
Closed Form ◽  
Three Dimensional ◽  
Plastic Collapse ◽  
Plastic Limit ◽  
Perfectly Plastic ◽  
Plastic Materials ◽  
Bending Mode ◽  
Wide Range ◽  
Plane Bending ◽  
Elastic Perfectly Plastic

Based on three-dimensional (3-D) FE limit analyses, this paper provides plastic limit, collapse and instability load solutions for pipe bends under combined pressure and in-plane bending. The plastic limit loads are determined from FE limit analyses based on elastic-perfectly plastic materials using the small geometry change option, and the FE limit analyses using the large geometry change option provide plastic collapse loads (using the twice-elastic-slope method) and instability loads. For the bending mode, both closing bending and opening bending are considered, and a wide range of parameters related to the bend geometry is considered. Based on the FE results, closed-form approximations of plastic limit and collapse load solutions for pipe bends under combined pressure and bending are proposed.

Use of API 579-1/ASME FFS-1 Limit-Load Criteria for Establishing Load Limits for Pressure Vessel Internals

2010 ◽  
Author(s):  
Brian R. Macejko
Keyword(s):  
Closed Form ◽  
Pressure Vessel ◽  
Limit Load ◽  
Process Equipment ◽  
Maximum Pressure ◽  
Plastic Collapse ◽  
Closed Form Solutions ◽  
Perfectly Plastic ◽  
Section Viii ◽  
Elastic Perfectly Plastic

The 2007 edition of ASME Boiler & Pressure Vessel Code Section VIII Division 2 and the 2007 edition of Fitness-For-Service API 579-1/ASME FFS-1 provide the option to use the limit-load method to assess protection against plastic collapse for components of pressurized process equipment. Per the methodology presented therein, the allowable load on a component is established by applying design factors to the elastic-perfectly plastic limit-load such that the onset of gross plastic deformation (plastic collapse) will not occur. Typically, the design limitations of pressure vessel internal components have been assessed through closed form solutions with conservative assumptions. It has been found that the maximum pressure delta across vessel internals established through closed form solutions can become limiting in determination of time between equipment shutdowns. This paper will outline a practical example of industry applied use of the limit-load method to qualify extended limits on mechanical loads applied to pressure vessel internals.

Closed-Form Collapse Moment Equations of Throughwall Circumferentially Cracked Elbows Subjected to In-Plane Bending Moment

2004 ◽  
Vol 126 (3) ◽  
pp. 307-317 ◽  
Author(s):  
J. Chattopadhyay ◽  
A. K. S. Tomar ◽  
B. K. Dutta ◽  
H. S. Kushwaha
Keyword(s):  
Closed Form ◽  
Bending Moment ◽  
Moment Equations ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Circumferential Crack ◽  
Opening Mode ◽  
Plane Bending ◽  
Elastic Perfectly Plastic ◽  
Bending Modes

A large throughwall circumferential crack in an elbow subjected to in-plane bending moment can significantly reduce its collapse load. Therefore, it is very important to know the collapse moment of an elbow in the presence of a throughwall circumferential crack. The existing closed-form collapse moment equations of throughwall circumferentially cracked elbows are either too conservative or inadequate to correctly quantify the weakening effect due to the presence of the crack, especially for opening mode of bending moment. Therefore, the present study has been carried out to investigate through elastic-plastic finite element analysis the effect of a throughwall circumferential crack on the collapse moment of an elbow under in-plane bending moment. A total of 72 cases of elbows with various sizes of circumferential cracks (2θ=0–150 deg), different wall thickness (R/t=5–20), different elbow bend radii Rb/R=2,3 and two different bending modes, namely closing and opening have been considered in the analysis. Elastic-perfectly plastic stress-strain response of material has been assumed. Collapse moments have been evaluated from moment-end rotation curves by twice-elastic slope method. From these results, closed-form expressions have been proposed to evaluate collapse moments of elbows under closing and opening mode of bending moment. The predictions of these proposed equations have been compared with 8 published elbow test data and are found to be within ±11% variation except for one case.

A Comparison of Flow and Deformation Theories in a Radially Stressed Annular Plate

1973 ◽  
Vol 40 (1) ◽  
pp. 283-287 ◽  
Author(s):  
P. C. T. Chen
Keyword(s):  
Internal Pressure ◽  
Closed Form ◽  
Deformation Theory ◽  
Annular Plate ◽  
Yield Condition ◽  
Flow Theory ◽  
Quantitative Comparison ◽  
The Other ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Two mathematically consistent solutions to the strains and displacement in a partly plastic, annular plate stressed by internal pressure are obtained according to the deformation theory of Hencky and to the flow theory of Prandtl-Reuss. In both cases, the material is assumed to be elastic, perfectly plastic and obeying the Mises yield condition. It is shown that one solution is expressed in closed form and the other, in terms of simple integrals. A quantitative comparison of two theories is given and the effect of compressibility is discussed.

Penetration of 6061-T651 Aluminum Targets With Rigid Long Rods

1988 ◽  
Vol 55 (4) ◽  
pp. 755-760 ◽  
Author(s):  
M. J. Forrestal ◽  
K. Okajima ◽  
V. K. Luk
Keyword(s):  
Closed Form ◽  
Cylindrical Cavity ◽  
Reasonable Agreement ◽  
Cavity Expansion ◽  
Cylindrical Cavity Expansion ◽  
Perfectly Plastic ◽  
Engineering Models ◽  
Elastic Perfectly Plastic ◽  
Penetration Depths

We developed engineering models for forces on rigid, long rods with spherical, ogival, and conical noses that penetrated rate independent, elastic-perfectly plastic targets. The spherical and cylindrical, cavity-expansion approximations simplified the target analyses, so we obtained closed-form penetration equations. To verify our models, we performed terminal-ballistic experiments with 7.1-mm dia., 0.024 kg, marging steel rods and 152-mm dia., 6061-T651 aluminum targets. The models predicted penetration depths that were in reasonable agreement with the data for impact velocities between 0.4-1.4 km/s.

scholarly journals A FEM analysis of the settlement of a tall building situated on loess subsoil

2020 ◽  
Vol 10 (1) ◽  
pp. 519-526
Author(s):  
Krzysztof Nepelski
Keyword(s):  
Fem Analysis ◽  
Actual Process ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Modified Cam Clay ◽  
Linear Behaviour ◽  
Subsequent Calculation ◽  
Elastic Perfectly Plastic ◽  
Subsoil Model ◽  
Storey Building

AbstractIn order to correctly model the behaviour of a building under load, it is necessary to take into account the displacement of the subsoil under the foundations. The subsoil is a material with typically non-linear behaviour. This paper presents an example of the modelling of a tall, 14-storey, building located in Lublin. The building was constructed on loess subsoil, with the use of a base slab. The subsoil lying directly beneath the foundations was described using the Modified Cam-Clay model, while the linear elastic perfectly plastic model with the Coulomb-Mohr failure criterion was used for the deeper subsoil. The parameters of the subsoil model were derived on the basis of the results of CPT soundings and laboratory oedometer tests. In numerical FEM analyses, the floors of the building were added in subsequent calculation steps, simulating the actual process of building construction. The results of the calculations involved the displacements taken in the subsequent calculation steps, which were compared with the displacements of 14 geodetic benchmarks placed in the slab.

Strength envelope of granular soil stabilized by multi-axial geogrid in large triaxial tests

2020 ◽  
Vol 57 (3) ◽  
pp. 448-452 ◽  
Author(s):  
A.S. Lees ◽  
J. Clausen
Keyword(s):  
Triaxial Compression ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Failure Envelope ◽  
Element Analysis ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Triaxial Compression Tests ◽  
Properties Of Soil

Conventional methods of characterizing the mechanical properties of soil and geogrid separately are not suited to multi-axial stabilizing geogrid that depends critically on the interaction between soil particles and geogrid. This has been overcome by testing the soil and geogrid product together as one composite material in large specimen triaxial compression tests and fitting a nonlinear failure envelope to the peak failure states. As such, the performance of stabilizing, multi-axial geogrid can be characterized in a measurable way. The failure envelope was adopted in a linear elastic – perfectly plastic constitutive model and implemented into finite element analysis, incorporating a linear variation of enhanced strength with distance from the geogrid plane. This was shown to produce reasonably accurate simulations of triaxial compression tests of both stabilized and nonstabilized specimens at all the confining stresses tested with one set of input parameters for the failure envelope and its variation with distance from the geogrid plane.

On the Conditions to Prevent Plastic Shakedown of Structures: Part I—Theory

1993 ◽  
Vol 60 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Castrenze Polizzotto
Keyword(s):  
Mechanical Load ◽  
Plastic Material ◽  
Perfectly Plastic ◽  
Shakedown Theory ◽  
Elastic Perfectly Plastic ◽  
Plastic Shakedown ◽  
Steady Load

For a structure of elastic perfectly plastic material subjected to a given cyclic (mechanical and/or kinematical) load and to a steady (mechanical) load, the conditions are established in which plastic shakedown cannot occur whatever the steady load, and thus the structure is safe against the alternating plasticity collapse. Static and kinematic theorems, analogous to those of classical shakedown theory, are presented.

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