Small plastic strain wave propagation in prestressed soft copper rods

This paper presents the strength and damage results based on elastic-plastic analysis to address the design feasibility of pulling in a steel catenary riser (SCR) through a pull tube with various bend configurations in a Spar. The example riser system contains an SCR of typical size, a tapered stress joint, a vertical pull tube with multiple bend sections, guide supports for the pull tube, and the associated pull head and pull chain connected to the top of the riser. The design methods discussed in the paper include: (1) Modeling of riser and pull tube in ABAQUS for strength analysis of the SCR; (2) Strain-based strain-life method to assess the associated fatigue damage; and (3) Strain-based Level 3B ECA design method to derive the critical surface flaw sizes for weld qualification of the SCR inside the pull tube. Comparisons are also presented between results derived from elastic and elastic-plastic analysis methods. The pull-in load on the example SCR increases with the water depth as well as the number and curvature of the bends on the pull tube. Calculated riser pull-in loads are about 11% to 51% higher than the submerged weight of the SCR. The elastic-plastic analysis shows small plastic zone and also small plastic strain on the example SCRs passing through pull tubes of a large bend radius of 125 ft. It also shows large plastic zone but small plastic strain on the SCR in a triple-bend pull tube with a small bend radius of 70 ft. The overall fatigue damage caused by cyclic plastic straining on the example SCRs due to pull in is lower than 3.3%. The allowable surface flaw sizes for the example SCRs are on the order of a × 2c = 8 × 10mm and 2.5 × 40mm for low aspect-ratio and high aspect-ratio surface flaws, respectively. Critical flaw sizes determined by Level 2A ECA are about 25% smaller than the flaw sizes based on Level 3B ECA for low aspect-ratio surface flaws. The specified maximum allowable flaw sizes are not very sensitive to the pull tube configuration and the water depth under the present study. The strength and damage analyses of SCR from other installation methods such as reeling are not included in this paper.

Download Full-text

Trigger for the occurrence of grain coarsening phenomenon of BS304S31 austenite stainless steel under small plastic strain at high temperature

Engineering Computations ◽

10.1108/02644400310488736 ◽

2003 ◽

Vol 20 (5/6) ◽

pp. 499-512 ◽

Cited By ~ 3

Author(s):

Masayoshi Akiyama ◽

Yutaka Neishi ◽

Yoshitaka Adachi ◽

Kenjiro Terada

Keyword(s):

Stainless Steel ◽

High Temperature ◽

Plastic Strain ◽

Grain Coarsening ◽

Austenite Stainless Steel ◽

Small Plastic ◽

Small Plastic Strain

Download Full-text

A connexion between the criterion of yield and the strain ratio relationship in plastic solids

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1947.0126 ◽

1947 ◽

Vol 191 (1027) ◽

pp. 441-446 ◽

Cited By ~ 14

Keyword(s):

Plastic Strain ◽

Yield Stress ◽

Principal Stress ◽

Strain Differences ◽

Strain Ratio ◽

Stress Criterion ◽

Small Plastic ◽

Maximum Work ◽

Work Done ◽

Small Plastic Strain

The assumption that the work done during a small plastic strain is a maximum as the yield - stress criterion is varied is shown to give rise to a connexion between the yield-stress and the strain-ratio relationship. The strain-ratio relationship is that which exists between the ratios of principal stress differences and the ratios of the corresponding strain differences. It is common to assume that this relationship is one of simple proportionality. Experiments, however, show that this assumption is not true in metals. The observed strain-ratio relationship is used in conjunction with the assumption of maximum work during a given strain to calculate the criterion of yield. It is found that this is very close to, but not identical with, the Mises-Heneky criterion.

Download Full-text

Creep of a Hollow Sphere

Journal of Applied Mechanics ◽

10.1115/1.2891985 ◽

1990 ◽

Vol 57 (2) ◽

pp. 276-281

Author(s):

T. Sakaki ◽

T. Kuroki ◽

K. Sugimoto

Keyword(s):

Thermal Stress ◽

Plastic Strain ◽

Hollow Sphere ◽

Strain Range ◽

Steady Creep ◽

Steady State Creep Rate ◽

Plastic Strain Range ◽

Small Plastic ◽

Numerical Calculation Method ◽

Small Plastic Strain

Using internal stress arising from a spherically symmetric, finite plastic strain, creep of a hollow sphere subjected to inner and outer pressures, and also thermal stress, is discussed. If computer-aided numerical calculation method is used, creep is easily followed up to a finite plastic strain range including initial transient creep, whatever type of creep law is employed. If assumed in a steady state, creep rate, stress, small plastic strain leading to a stress state in steady creep, and another small plastic strain relaxing thermal stress are analytically obtained. Numerical method is also applicable to creep relaxation. Further, the origin of residual stress after unloading is clarified.

Download Full-text

Error Bounds on Elastic-Plastic Strain Wave Measurements

Journal of Basic Engineering ◽

10.1115/1.3425284 ◽

1971 ◽

Vol 93 (4) ◽

pp. 478-480 ◽

Cited By ~ 1

Author(s):

J. G. Wagner

Keyword(s):

Wave Propagation ◽

Plastic Strain ◽

Lower Bounds ◽

Upper And Lower Bounds ◽

Strain Wave ◽

One Dimensional ◽

Elastic Plastic ◽

Strain Behavior ◽

Wave Measurements ◽

Dimensional Wave

Bounds are established on the errors associated with elastic-plastic strain wave measurements involving finite gage lengths. Attention is restricted to the case of one-dimensional wave propagation in a semi-infinite bar. A bi-linear model of the stress-strain behavior provides a means of calculating realistic upper and lower bounds on the relative error of amplitude measurements. Rise time errors are also discussed and illustrated.

Download Full-text

Abundant exact solutions to the strain wave equation in micro-structured solids

Modern Physics Letters B ◽

10.1142/s021798492150439x ◽

2021 ◽

pp. 2150439

Author(s):

Karmina K. Ali ◽

R. Yilmazer ◽

H. Bulut ◽

Tolga Aktürk ◽

M. S. Osman

Keyword(s):

Wave Propagation ◽

Wave Equation ◽

Exact Solutions ◽

Rational Function ◽

Physical Interpretation ◽

Function Method ◽

Nonlinear Partial Differential Equations ◽

Singular Solutions ◽

Strain Wave ◽

Important Place

In this study, the strain wave equation in micro-structured solids which take an important place in solid physics is presented for consideration. The generalized exponential rational function method is used for this purpose which is one of the most powerful methods of constructing abundantly distinct, exact solutions of nonlinear partial differential equations. In micro-structured solids, wave propagation is based on the structure of the strain wave equation. As a consequence, we successfully received many different exact solutions, including non-topological solutions, periodic singular solutions, topological solutions, singular solutions, like periodic lump solutions. Furthermore, in order to better understand their physical interpretation, 2D, 3D, and counter plots are graphed for each of the solutions acquired.

Download Full-text