Comparison of J-Integral Measurement Methods on Clamped Single-Edge Notched Tension Specimens

2016 ◽  
Author(s):  
Timothy S. Weeks ◽  
Jeffrey W. Sowards ◽  
Ross A. Rentz ◽  
David T. Read ◽  
Enrico Lucon
Keyword(s):  
Mouth Opening ◽  
Surface Strain ◽  
Image Correlation ◽  
Crack Mouth Opening Displacement ◽  
J Integral ◽  
Crack Mouth ◽  
Single Edge ◽  
Opening Displacement ◽  
Strain Gradients

This paper reports an extension of a previous study that compared methods of evaluating J by the crack mouth opening displacement and by surface strain gradients. Here, the surface strain gradients are measured by three-dimensional digital image correlation. The results herein represent a small test matrix that involved evaluation of the J-integral for clamped single-edge notched tensile specimens from API 5L X65 base-metal, weld metal and the adjacent heat affected zone; the J-integral was evaluated by a standardized procedure utilizing the crack mouth opening displacement (CMOD) and by the contour integral method on an external surface strain contour. Digital image correlation provides sufficient full-field strain data for use by this method and is considerably more robust than surface-mounted strain gage instrumentation. A series of validity checks are presented that demonstrate that the data are useful and valuable. Experimental determination of the J-integral is not limited to thoroughly analyzed test geometries and may be achieved with limited instrumentation. Furthermore, the method described does not require a determination of crack size nor any instrumentation that requires access to the crack mouth.

Impact fracture behaviors of three-dimensional braided composite U-notch beam subjected to three-point bending

2018 ◽  
Vol 28 (3) ◽  
pp. 404-426 ◽  
Author(s):  
Baohui Shi ◽  
Shengkai Liu ◽  
Amna Siddique ◽  
Yongcan Du ◽  
Baozhong Sun ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Mouth Opening ◽  
Impact Fracture ◽  
Image Correlation ◽  
Crack Mouth Opening Displacement ◽  
Crack Mouth ◽  
Opening Displacement ◽  
Braided Composite ◽  
Fracture Behaviors ◽  
The Impact

Impact fracture behaviors of three-dimensional braided composites are critical to designing the braided composite parts. Here we report the impact fracture behaviors of three-dimensional braided composite U-notch beam tested on a modified split Hopkinson pressure bar. Crack mouth opening displacement, deformation process, and crack evolutions were recorded with high-speed photography camera. The digital image correlation method was used to calculate deformation contours of the braided composite. A microstructure model of the three-dimensional braided composite U-notch beam was established for analyzing damage evolution and fracture mechanisms. The histories of deformation, the load, and the crack mouth opening displacement were obtained from the impact fracture test and finite element analysis. It was found that the impact fracture resistance and morphologies were influenced by the braided structure and braided yarn orientations. The crack generated at the notch tip and then propagated along the braided angle direction rather than the perpendicular direction that often occurred for isotropic materials, such as the epoxy resin solid. The combinations of different braided angle and yarns are recommended for high impact fracture behavior design.

Revised Incremental J-Integral Equations for ASTM E1820 Using the Crack Mouth Opening Displacement

2009 ◽  
Vol 37 (3) ◽  
pp. 102183 ◽  
Author(s):  
M. R. Mitchell ◽  
R. E. Link ◽  
Xian-Kui Zhu ◽  
James A. Joyce
Keyword(s):  
Integral Equations ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
J Integral ◽  
Crack Mouth ◽  
Opening Displacement

Development of a Low-Constraint SE(T) Toughness Test

2011 ◽  
Vol 488-489 ◽  
pp. 126-129 ◽  
Author(s):  
W. R. Tyson ◽  
G. Shen ◽  
J. A. Gianetto ◽  
D.Y. Park
Keyword(s):  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
J Integral ◽  
Single Edge ◽  
Opening Displacement ◽  
Bending Loads ◽  
Low Constraint ◽  
Girth Welds ◽  
Crack Tip Constraint ◽  
Tension Loading

CANMET-MTL has developed a low-constraint test designed to reduce unnecessary conservatism in the measurement of toughness for use in the assessment of flaws in pipeline girth welds. The design is based on tension loading using fixed (clamped) grips of a single-edge-notched BxB SE(T) specimen, side-grooved to promote plane-strain conditions. Equations have been developed to derive J-integral, CTOD and crack growth from measurement of load and crack-mouth opening displacement. Loading conditions (essentially distance between the grips) have been chosen to reproduce the crack-tip constraint of a circumferential surface flaw in a pipe in service under tensile or bending loads. In this paper, the development of the test and the principal findings from its use will be described.

Effect of Side Grooves on Compliance, J-Integral and Constraint of a Clamped SE(T) Specimen

2010 ◽  
Author(s):  
Guowu Shen ◽  
William R. Tyson ◽  
James A. Gianetto ◽  
Dong-Yeob Park
Keyword(s):  
Plane Strain ◽  
Crack Depth ◽  
Mouth Opening ◽  
Crack Tip ◽  
Crack Mouth Opening Displacement ◽  
J Integral ◽  
Single Edge ◽  
Opening Displacement ◽  
Element Analysis ◽  
Crack Tip Constraint

The effect of side grooves on crack mouth opening displacement (CMOD) compliance, distribution of J-integral and crack-tip constraint parameters Q and A2 along the thickness of a clamped single-edge-notched tension (SE(T)) specimen were studied by finite element analysis (FEA). Focus was on the effect of depth of side grooves on J-integral and constraint parameters Q and A2 for shallow and deep cracks. The 3-D results were compared with those of SE(T) specimens in plane strain. The results show that the effective thickness equation used in ASTM E 1820 to evaluate compliance of side-grooved SE(B) and C(T) specimens can be used for clamped SE(T) specimens with reasonable accuracy. The results also suggest that the depth of the side grooves affects the distribution of the J-integral: the highest J-integral is at the center of the thickness for a SE(T) specimen with side grooves equal to or less than 10% of total thickness, and near the root of the side grooves for side grooves greater than 10% for a deeply-cracked specimen when the applied load P≥PY. The FEA results also show that the depth of side grooves affects the distribution of the constraint parameters: the crack-tip constraint is highest at the center of the thickness for a specimen with 0% side grooves (plain-sided), and near the root of the side grooves for side grooves equal to or greater than 10%. It was also found from FEA that the crack-tip constraint of a SE(T) specimen with 20% side grooves with shallow (a/W = 0.2) or deep (a/W = 0.5) crack is higher than that of a SE(T) specimen with the same crack depth in plane strain. As a result, the J-resistance of a SE(T) specimen with 20% side grooves may be lower than that of the same specimen in plane strain.

Comparison study of crack propagation in rubberized and conventional prestressed concrete sleepers using digital image correlation

2021 ◽  
pp. 095440972110205
Author(s):  
Guoqing Jing ◽  
Du yunchang ◽  
Ruilin You ◽  
Mohammad Siahkouhi
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Prestressed Concrete ◽  
Mouth Opening ◽  
Image Correlation ◽  
Crack Mouth Opening Displacement ◽  
Experimental Program ◽  
Pure Bending ◽  
Opening Displacement ◽  
Rubber Concrete

Rubber concrete (RC) has been confirmed to be suitable for concrete sleeper production. This paper studies the cracking behaviour of conventional and rubber-reinforced concrete sleepers based on the results of an experimental program. The cracking behaviour in the pure bending zone was analysed up to a load of 140 kN. The crack mouth opening displacement (CMOD) was accordingly measured using a digital image correlation (DIC) method. The DIC results show that the rubber prestressed concrete sleeper (RPCS) has a resistance against crack initiation that is 20% greater than that of the conventional prestressed concrete sleeper (CPCS) under the same loading condition; however, due to the higher crack growth rate of the RPCS, the first crack detected by the operator forms at 60 kN, which corresponds to a strength approximately 9% lower compared with the 65 kN load at which the first crack is detected in the CPCS. Before the first crack (60 kN), the RPCS has a deflection 35% lower than that of the CPCS, but after cracking, at loads of 80 kN, 100 kN and 140 kN, the RPCS has a deflection 15%, 4% and 24% higher than that of the CPCS, respectively.

A Crack Mouth Opening Displacement Gauge made with Passive UHF RFID Technology

2021 ◽  
pp. 1-1
Author(s):  
A. DiNatale ◽  
A. DiCarlofelice ◽  
E. DiGiampaolo
Keyword(s):  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Rfid Technology ◽  
Uhf Rfid ◽  
Crack Mouth ◽  
Opening Displacement ◽  
Passive Uhf Rfid

Wide Range Compliance Solutions for Various Fracture Test Specimens Using Crack Mouth Opening Displacement

2017 ◽  
Author(s):  
Claudio Ruggieri ◽  
Rodolfo F. de Souza
Keyword(s):  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Width Ratio ◽  
Fracture Test ◽  
Single Edge ◽  
Opening Displacement ◽  
Element Analysis ◽  
Single Edge Notch ◽  
Wide Range ◽  
Edge Notch

This work addresses the development of wide range compliance solutions for tensile-loaded and bend specimens based on CMOD. The study covers selected standard and non-standard fracture test specimens, including the compact tension C(T) configuration, the single edge notch tension SE(T) specimen with fixed-grip loading (clamped ends) and the single edge notch bend SE(B) geometry with varying specimen spam over width ratio and loaded under 3-point and 4-point flexural configuration. Very detailed elastic finite element analysis in 2-D setting are conducted on fracture models with varying crack sizes to generate the evolution of load with displacement for those configurations from which the dependence of specimen compliance on crack length, specimen geometry and loading mode is determined. The extensive numerical analyses conducted here provide a larger set of solutions upon which more accurate experimental evaluations of crack size changes in fracture toughness and fatigue crack growth testing can be made.

scholarly journals Estimation of Crack Mouth Opening Displacement in Concrete Using Optical Fiber Sensors

2018 ◽  
Vol 03 (01) ◽  
Author(s):  
Sobha B ◽  
Samrajyam K ◽  
Sai Prasad RLN ◽  
Rao GTD
Keyword(s):  
Optical Fiber ◽  
Mouth Opening ◽  
Optical Fiber Sensors ◽  
Crack Mouth Opening Displacement ◽  
Crack Mouth ◽  
Opening Displacement ◽  
Fiber Sensors

TEST STUDY ON THE BEST PASTING LAYER OF FRP REINFORCED CONCRETE

2019 ◽  
Vol 27 (02) ◽  
pp. 1950105
Author(s):  
XIANGQIAN FAN ◽  
JUEDING LIU
Keyword(s):  
Fracture Toughness ◽  
Acoustic Emission ◽  
Reinforced Concrete ◽  
Crack Depth ◽  
Mouth Opening ◽  
Bending Test ◽  
Crack Mouth Opening Displacement ◽  
Displacement Curve ◽  
Crack Mouth ◽  
Opening Displacement

To optimize the strengthening method using the fiber reinforced polymer (FRP) for the reinforcement of the concrete structure with cracks, the three-point bending test was conducted on the concrete beams wrapped with different layers of FRP materials. The strain gauges were pasted on the surface of the specimens to measure the initial cracking load. The crack mouth opening displacement (CMOD) was utilized to test the load–crack mouth opening displacement curve. According to the improved calculation formula of the fracture toughness, the critical effect crack length [Formula: see text], initiation fracture toughness [Formula: see text] and instability fracture toughness [Formula: see text] of specimens were calculated. The test results showed that, under the same initial crack depth, the peak load of FRP reinforced concrete decreases with the increase of FRP pasting layer. When there was one layer wrapped over the specimen, the instability toughness of the specimen reached the maximum value and the crack resistance was the best. Based on acoustic emission testing method, the acoustic emission parameters of the above-mentioned concrete during fracture process were identified and collected. The optimal layer of the FRP reinforced concrete with cracks was analyzed from the acoustic emission method.

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