A Study on the Estimation of Fracture Behaviour for a Circumferentially Through-Wall Cracked Pipe

2007 ◽  
Vol 120 ◽  
pp. 15-20
Author(s):  
Weon Keun Song ◽  
Jae Sil Park
Keyword(s):  
Fracture Behavior ◽  
Standard Specimen ◽  
Separation Method ◽  
Experimental Results ◽  
Displacement Curve ◽  
Fracture Test ◽  
Load Line ◽  
Load Line Displacement ◽  
Load Separation ◽  
Geometry Function

It is known that fracture characteristics are changed due to the geometric configuration. Also, it is known that toughness data obtained from the standard specimen test are conservative to predict fracture behavior of the real piping. Thus fracture behavior by tests of pipes would to be applied to the integrity evaluation for the piping system. However, fracture test with real pipe is not only difficult to perform but also very expensive, and requires lots of experience. So an estimation method of pipe’s fracture behavior is necessary to solve this problem. The objective of this thesis is to propose a method to estimate the fracture behavior of a pipe from the result of the standard specimen fracture test. For this, fracture tests for standard specimens and pipes are conducted. The resultant load - load-line displacement record of the standard specimen was transformed to that of a pipe by load separation method. To begin with, the load versus load-line displacement curve of a standard specimen extracted from a pipe is normalized by a geometry function of the CT specimen. Then this normalized curve was converted to pipe’s load versus displacement curve by a geometry function of pipe. To verify the constraint factor and the geometric function of pipe, finite element analyses were performed. To demonstrate the proposed method, experimental results of pipes are compared with predicted results. Calculated results from CT specimens are similar to experimental results of pipes. Therefore the transformability from a CT specimen to a pipe by load separation method is proved. Consequently the applicability of the proposed method was proved.

A Study on Estimation of the Pipe Fracture Characteristics

2006 ◽  
Vol 321-323 ◽  
pp. 541-544
Author(s):  
Jae Sil Park ◽  
Chang Sung Seok
Keyword(s):  
Fracture Resistance ◽  
Fracture Behavior ◽  
Standard Specimen ◽  
Crack Mouth Opening Displacement ◽  
Ratio Method ◽  
Piping System ◽  
Resistance Curve ◽  
Fracture Test ◽  
Fracture Characteristics ◽  
The Real

In order to analyze the elastic-plastic fracture behavior of a structure, the fracture resistance curve of the material should be known. However, it is difficult to evaluate the fracture characteristics with an experiment on the piping system. Instead, the fracture toughness obtained from standard specimen tests is used to analyze the structure and assess the fracture characteristics of the total structure. It is known that toughness data from the standard specimen test are conservative to predict fracture behavior of the real piping. Thus the fracture resistance curve by the fracture test of the real scaled pipe specimen would be applied to the integrity evaluation for the piping system. However, it is not only difficult to perform but also very expensive to perform full-scale pipe tests. The objective of this thesis is to propose a method to estimate the fracture resistance curve of a pipe from the result of standard specimen fracture test. To estimate the fracture resistance curve for a pipe specimen, load – load-line displacement records of a standard specimen were transformed to those of the pipe specimen. The load ratio method was proposed in order to calculate the crack length from load – crack mouth opening displacement records for the pipe specimen. To prove the validity of this estimation results, fracture tests for pipe specimens were performed. Consequently the applicability of the proposed method was investigated by comparing estimated results with tested results.

Dynamic J-Integral Evaluation of Three-Point-Bend Beams with Various Geometrical Dimensions

2011 ◽  
Vol 488-489 ◽  
pp. 630-633
Author(s):  
Marius Gintalas ◽  
Antanas Žiliukas ◽  
Kaspars Kalniņš
Keyword(s):  
Fracture Toughness ◽  
Plastic Material ◽  
Rectangular Cross Section ◽  
Estimation Method ◽  
Displacement Curve ◽  
Elastic Plastic ◽  
Load Line ◽  
Load Line Displacement ◽  
Specimen Test

J-Integral is the main effective and commonly used tool for cracked elastic-plastic material resistance assessment. Determination of fracture toughness under impact loading conditions is related with problems of crack length measurement. Nevertheless, current experimental techniques restrict the specimen’s geometry taking into account span and height ratio, which is equal to four. Evaluation of fracture toughness estimation method which requires only experimental load-line displacement curve of single specimen is research object of dynamic fracture mechanics. This article proposes an approach of impact fracture toughness determination of elastic-plastic steel from single any size specimen test. Load-line displacement data obtained from three-point-bending tests of rectangular cross section specimens with V form single edge notch was used for J-integral calculation. Five series of specimens with different geometry were manufactured from ductile steel and tested.

scholarly journals Experimental Study and Extended Finite Element Simulation of Fracture of Self-Compacting Rubberized Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xinquan Wang ◽  
Hongguo Diao ◽  
Yunliang Cui ◽  
Changguang Qi ◽  
Shangyu Han
Keyword(s):  
Finite Element ◽  
Loading Rate ◽  
High Performance Concrete ◽  
The Self ◽  
Experimental Results ◽  
Crack Mouth Opening Displacement ◽  
Displacement Curve ◽  
Rubberized Concrete ◽  
Extended Finite Element ◽  
Self Compacting Concrete

Self-compacting rubberized concrete (SCRC) is a high-performance concrete that can achieve compacting effect by self-gravity without vibration during pouring. Because of its excellent fluidity, homogeneity, and stability, the application of self-compacting concrete in engineering can improve work efficiency and reduce project cost. The effects of loading rate on the fracture behavior of self-compacting concrete were studied in this paper. Three-point bend (TPB) tests were carried out at five loading rates of 1, 0.1, 0.001, 0.0001, and 0.00001 mm/s. The dimensions of the specimens were 100  mm × 100 mm × 400 mm. A precast crack was set in the middle of the specimen with a notch-depth ratio of 0.4. The experimental results show that the peak load on the load-CMOD (crack mouth opening displacement) curve gradually increases with the increase of the loading rate. Although the fracture energy a presented greater dispersion under the loading rate of 1 mm/s, the overall changes were still rising with the increase of the loading rate. Besides studying the softening characteristics of the self-compacting concrete, the constitutive softening curve of the self-compacting concrete was obtained using the bilinear model. Finally, curved three-point bending beams were simulated by using the extended finite element method based on ABAQUS. The fracture process of the self-compacting concrete under different loading conditions was analyzed more intuitively. The simulation results were compared with the experimental results, and the same conclusions were obtained.

Sensitivity Analysis for the Transverse Displacements of a Cracked Plate Using the Spatial Wavelet Approach

2005 ◽  
Author(s):  
H. Y. Sun ◽  
Y. Y. Lee ◽  
H. F. Lam ◽  
R. K. L. Su
Keyword(s):  
Finite Element Method ◽  
Sensitivity Analysis ◽  
Natural Frequencies ◽  
Experimental Results ◽  
Displacement Curve ◽  
Plate Surface ◽  
Wavelet Method ◽  
Crack Location ◽  
Cracked Plates ◽  
Small Cracks

In this paper, the effectiveness of the proposed technique is used for the sensitivity analysis of cracked plates, and verified theoretically and experimentally. The transverse displacements and natural frequencies of cracked plates are obtained using the fractal two-level finite element method The transverse displacements of the cracked plates are then transformed using the spatial wavelet method. The numerical and experimental results have concluded that 1) the natural frequencies are not very sensitive to small cracks. The presences of the small cracks and crack locations cannot be identified effectively by examining the natural frequencies; 2) the transformed transverse displacements are more sensitive to the crack extent and change significantly at the crack locations, provided that the wavelet dilation index is high enough (i.e., the wavelet transform resolution is fine enough); 3) however, the experimental results show that if the wavelet dilation index is set too high, the crack locations cannot be detected from the transformed displacements. It is because the plate surface roughness in the experiment cases induces some local variations on the transformed displacement curve to mask the crack location.

Applicability of J Estimation Procedures for Overmatched SE(T) Fracture Specimens

2010 ◽  
Author(s):  
Lenin M. Paredes ◽  
Henrique S. S. Carvalho ◽  
Claudio Ruggieri
Keyword(s):  
Primary Objective ◽  
Weld Strength ◽  
Evaluation Procedure ◽  
Single Edge ◽  
Load Line ◽  
Load Line Displacement ◽  
Edge Notch ◽  
Η Factor ◽  
Fracture Specimens ◽  
J Estimation

This work focuses on the evaluation procedure to determine the elastic-plastic fracture toughness J-integral based upon the η-method for welded SE(T) fracture specimens. The primary objective of this investigation is to address the significance of the η-factor on accurate and robust estimates of J clamped single edge notch tension (SE(T)) specimens using load-displacement records. Very detailed non-linear finite element analyses for plane-strain models provide the evolution of load with increased load-line displacement to define the applied load as a separable function dependent upon crack geometry, strength mismatch level and specimen deformation. The analyses reveal that η-factors for clamped SE(T) fracture specimens based on load-line displacement (LLD) records and plastic area are relatively insensitive to weld strength mismatch.

Explicit formulation for the axial collapse of a pipe during drilling

2010 ◽  
Vol 224 (8) ◽  
pp. 1547-1549
Author(s):  
A Almasi
Keyword(s):  
Closed Form ◽  
Plastic Hinge ◽  
Variable Length ◽  
Experimental Results ◽  
Displacement Curve ◽  
Explicit Formulation ◽  
Theoretical Predictions ◽  
Hinge Zone ◽  
Good Agreement

New closed-form expressions are introduced for ax-symmetric progressive axial collapse of pipes that use a plastic folding mechanism based on variable length of an active plastic hinge zone. A procedure for determination of a load—displacement curve of axial pipe collapse is presented. Theoretical predictions give a good agreement with the experimental results owing to the influence of presented new refinements.

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