Simplified, Detailed, and Isochronous Analysis and Test Results for the In-Plane Elastic-Plastic and Creep Behavior of an Elbow

1986 ◽  
Vol 108 (3) ◽  
pp. 297-304 ◽  
Author(s):  
L. H. Sobel ◽  
S. Z. Newman
Keyword(s):  
Creep Behavior ◽  
Bending Moment ◽  
Time Dependent ◽  
304 Stainless Steel ◽  
Plastic Behavior ◽  
Test Results ◽  
Creep Properties ◽  
Elastic Plastic ◽  
Creep Analysis ◽  
Simplified Analysis

Predictions obtained from simplified and detailed MARC analyses are compared with experimental results for the elastic-plastic and creep behavior of a 16-in-dia 304 stainless steel piping structure subjected to an in-plane closing bending moment. The piping structure is composed of a 90-deg elbow and two straight tangent pipes. The simplified analysis is found to considerably overestimate the measured results, especially for the case of creep behavior. The correlation of detailed analysis predictions with measured results is satisfactory for the elastic-plastic behavior of the structure, and inconclusive for the creep behavior, since the creep predictions are based on a commonly used creep law rather than on the actual (but unmeasured) creep properties. The paper also shows that predictions of creep deformation obtained from the relatively inexpensive time-independent isochronous method of analysis agree well with results given by a “complete” and more costly time-dependent creep analysis.

Load Regime Diagram of a Pipe With Cyclically Plastic Bending

2002 ◽  
Author(s):  
Yanping Yao ◽  
Ming-Wan Lu
Keyword(s):  
Axial Force ◽  
Bending Moment ◽  
Boundary Curve ◽  
Plastic Behavior ◽  
Cyclic Bending ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Load Regime ◽  
Reversed Cyclic ◽  
Cyclic Bending Moment

The criteria of piping seismic design based on linear elastic analysis has been proved to be conservative, which is mainly because the influence of plastic deformation on piping dynamic response is neglected. In the present paper, a pipe under seismic excitation is simplified as an beam with tubular cross section subjected to steady axial force and fully reversed cyclic bending moment, and the elastic-plastic behavior of the pipe is studied. Various behavior of the pipe under different combinations of axial force and cyclic bending moment is discussed and the boundary curve equations between them are obtained. Also the load regime diagram for a pipe which is formed by the boundary curve equations in the loading plane is given, from which the elastic-plastic behavior of the pipe can be determined directly.

MULTI-SCALE CREEP ANALYSIS OF PLAIN-WOVEN LAMINATES USING TIME-DEPENDENT HOMOGENIZATION THEORY: EFFECTS OF LAMINATE CONFIGURATION

2008 ◽  
Vol 22 (31n32) ◽  
pp. 6173-6178 ◽  
Author(s):  
K. NAKATA ◽  
T. MATSUDA ◽  
M. KAWAI
Keyword(s):  
Boundary Condition ◽  
Glass Fiber ◽  
Creep Behavior ◽  
Present Method ◽  
Time Dependent ◽  
Homogenization Theory ◽  
Multi Scale ◽  
Creep Analysis ◽  
Internal Structures ◽  
Woven Glass Fiber

In this study, multi-scale creep analysis of plain-woven GFRP laminates is performed using the time-dependent homogenization theory developed by the present authors. First, point-symmetry of internal structures of plain-woven laminates is utilized for a boundary condition of unit cell problems, reducing the domain of analysis to 1/4 and 1/8 for in-phase and out-of-phase laminate configurations, respectively. The time-dependent homogenization theory is then reconstructed for these domains of analysis. Using the present method, in-plane creep behavior of plain-woven glass fiber/epoxy laminates subjected to a constant stress is analyzed. The results are summarized as follows: (1) The in-plane creep behavior of the plain-woven GFRP laminates exhibits marked anisotropy. (2) The laminate configurations considerably affect the creep behavior of the laminates.

Effect of Temperature Variation on Cyclic Elastic-Plastic Behavior of SUS 304 Stainless Steel

1990 ◽  
Vol 112 (2) ◽  
pp. 152-157 ◽  
Author(s):  
Y. Niitsu ◽  
K. Ikegami
Keyword(s):  
Stainless Steel ◽  
Temperature Variation ◽  
Cyclic Hardening ◽  
Experimental Results ◽  
304 Stainless Steel ◽  
Effect Of Temperature ◽  
Plastic Behavior ◽  
Elastic Plastic ◽  
Temperature Conditions ◽  
Hardening Models

The cyclic elastic-plastic behavior of SUS 304 stainless steel was investigated experimentally under various temperatures and temperature-changing conditions. The specimens were cyclically loaded between fixed axial strain limits at constant temperatures in the range from room temperature to 600°C. The effects of the cyclic strain amplitude on the saturation property of cyclic hardening were obtained at various temperatures. The effects of temperature variations on the cyclic hardening were examined under the temperature conditions of changing between two different temperatures. From these experimental results, the effects of the temperature variation on the saturation properties were found under several temperature conditions. The three different hardening models accounting for these cyclic hardening properties were proposed. The experimental results were compared with the results calculated by those three cyclic hardening models.

Full Life Elastic-Plastic-Creep Analysis and Comparison to Tests of Axially Cycled Pressurized Tubular Specimens

1982 ◽  
Vol 104 (2) ◽  
pp. 96-101
Author(s):  
I. Berman ◽  
M. S. M. Rao ◽  
G. D. Gupta
Keyword(s):  
Material Properties ◽  
Fatigue Behavior ◽  
Test Results ◽  
Elastic Plastic ◽  
Creep Analysis ◽  
Creep Fatigue ◽  
Incoloy 800 ◽  
Full Life ◽  
Tubular Specimens ◽  
Plastic Creep

Full life elastic-plastic-creep analyses of axially cycled pressurized tubular 316H stainless steel and Incoloy 800 specimens were run in order to evaluate creep ratcheting and creep fatigue behavior. Analytical results were obtained for the loading conditions and the 593°C (1100°F) material properties of the tests reported by Majumdar [1]. Both “book” value and other material property assumptions were used in the analyses and compared with the test results. Some conclusions from these tests are that book property analyses can, in some cases, underestimate the results. Modification of the material properties to more closely mirror actual conditions can, in some cases, greatly improve the predictions.

Simplified Inelastic Time Independent (SITI) Method for Predicting Creep

2007 ◽  
Author(s):  
Jeries J. Abou-Hanna ◽  
Osama Ali ◽  
Venkata Tatikonda ◽  
Timothy E. McGreevy
Keyword(s):  
Creep Behavior ◽  
Inelastic Strain ◽  
Material Model ◽  
Time Dependent ◽  
Computationally Efficient ◽  
Element Analysis ◽  
State Variable ◽  
Creep Analysis ◽  
Inelastic Strains ◽  
Very High

In an effort to address inelastic creep behavior for very high temperature (VHT) applications, a unified state variable material model was used in a time dependent finite element analysis to generate isochronous curves. The resulting isochronous curves were then used in an efficient time-independent plastic analysis to predict the creep behavior of components. This simplified inelastic time-independent (SITI) method can significantly reduce the geometric and load uncertainties, and the over-conservatism in predicting inelastic strain levels. SITI is an effective and computationally efficient approach for predicting inelastic strains of components operating at high and very high temperatures such as the case in the Next Generation Nuclear Plant. This work compares the SITI inelastic strains to those obtained using fully inelastic time-dependent elastic-plastic-creep analysis, and illustrates the effectiveness of the approach in obtaining creep strain predictions without elaborate full inelastic time-dependent simulation.

Numerical Study of Defect Free Elbows Subjected to In-Plane Bending Moment

2011 ◽  
Vol 189-193 ◽  
pp. 1494-1497
Author(s):  
Wang Chen ◽  
Yin Pei Wang ◽  
Pei Ning Li ◽  
Chen Jin ◽  
Xiao Ming Sun
Keyword(s):  
Numerical Study ◽  
Plastic Material ◽  
Three Dimensional ◽  
Bending Moment ◽  
Plastic Behavior ◽  
Piping System ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Bending Radius ◽  
Elastic Perfectly Plastic

Elbow is a type of components widely used in a piping system, and so it is very important to know the plastic carrying capacity of elbow. In this study, the elastic-plastic behavior of elbows with various ratios of t/rm and relative bending radius R/rm were investigated in detail by using of three-dimensional (3D) non-linear finite element (FE) analyses, assuming elastic-perfectly-plastic material behaviour and taking geometric nonlinearity into account. The analyses indicated that elbow exhibited different behavior obviously at the elastic-plastic states subjected to In-Plane opening bending moment and closing bending moment. The closed form equations of elbow involving effect of tangent pipes were established.

Plastic Behaviour of Small Bore Piping Bend/Elbow Under Combined Internal Pressure and Bending Moment

2011 ◽  
Author(s):  
Xinjian Duan ◽  
Michael Kozluk
Keyword(s):  
Internal Pressure ◽  
Bending Moment ◽  
Plastic Behavior ◽  
Test Results ◽  
Modes Of Failure ◽  
Wall Loss ◽  
Cold Worked ◽  
Loading Modes ◽  
Reactor Operating ◽  
Design Pressure

This paper presents some preliminary observations from six representative tests on the plastic behavior of small bore carbon steel piping bends/elbows with general and local wall loss subject to combined internal pressure and bending moment loading at typical CANDU® reactor operating temperature. These six tests include three materials (normalized elbow, stress relieved bend and cold worked bend), two piping sizes (NPS 2 and NPS 2 1/2), two loading modes (monotonic and cyclic) and three modes of failure (collapse, burst and leak). The test results show that a collapsed piping bend/elbow can still withstand five times design pressure without the loss of pressure boundary. The stress relieved bend appears to offer a compromise in the resistance to both environmental assisted cracking and plastic collapse relative to the normalized elbow and cold worked bend.

Elevated Temperature Elastic-Plastic-Creep Test of an Elbow Subjected to In-Plane Moment Loading

1977 ◽  
Vol 99 (2) ◽  
pp. 291-297 ◽  
Author(s):  
A. Imazu ◽  
R. Miura ◽  
K. Nakumura ◽  
T. Nagata ◽  
K. Okabayashi
Keyword(s):  
Creep Behavior ◽  
304 Stainless Steel ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Curved Pipes ◽  
Theoretical Predictions ◽  
Stationary Creep ◽  
Type 304 ◽  
Type 304 Stainless Steel ◽  
Plastic Creep

This paper describes the results of test on elastic-plastic-creep behavior of a 12-in. Sch. 20 type 304 stainless steel elbow-pipe assembly subjected to in-plane moment loading at 600°C (1112°F). During the test, loads at seven different levels were applied to the specimen. In each stage of the test, the load, deflection, strains at specific locations, and ovalization of the cross section were measured. The results were compared with Spence’s theoretical predictions on the stationary creep behavior of smooth curved pipes and the inelastic solutions obtained by the MARC finite element analysis program.

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