Experimental Investigation Into the Fracture Toughness of Polyethylene Pipe Material

2005 ◽  
Vol 127 (1) ◽  
pp. 70-75 ◽  
Author(s):  
Ihab Mamdouh Graice ◽  
Maher Y. A. Younan ◽  
Soheir Ahmed Radwan Naga
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Experimental Tests ◽  
Compact Tension ◽  
Test Method ◽  
Elastic Behavior ◽  
Plastic Behavior ◽  
Specimen Thickness ◽  
Pipe Material ◽  
Opening Displacement

The mechanical behavior of the recently produced gas pipes material PE100 is investigated and compared to the commonly used material PE80 to determine their relative advantages. The two materials show plastic behavior at room temperature. The fracture toughness of the two materials is experimentally determined using the two common elastic plastic fracture mechanics methods: the American Society for Testing and Materials (ASTM) multiple specimen test method for determining the J-R curve of the materials, and the crack opening displacement method. The investigation of the fracture behavior of the two materials includes the effect of the specimen thickness as well as specimen configuration. The experimental tests were carried on the compact tension specimens and the single edge notch bending (SENB) specimens. At −70°C, the materials show elastic behavior, the ASTM test method for determining fracture toughness is applied to SENB specimens to determine KIC of both materials. PE80 shows greater resistance to fracture than PE100.

Experimental Investigation Into the Fracture Toughness of Polyethylene Pipe Material

2004 ◽  
Author(s):  
Ihab Mamdouh Graice ◽  
Maher Y. A. Younan ◽  
Soheir Ahmed Radwan Naga
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Experimental Tests ◽  
Compact Tension ◽  
Test Method ◽  
Elastic Behavior ◽  
Plastic Behavior ◽  
Specimen Thickness ◽  
Pipe Material ◽  
Opening Displacement

The mechanical behavior of the recently produced gas pipes material PE100 is investigated and compared to the commonly used material PE80 to determine their relative advantages. The two materials show plastic behavior at room temperature. The fracture toughness of the two materials is experimentally determined using the two common elastic plastic fracture mechanics methods: the ASTM multiple specimen test method for determining the J-R curve of the materials, and the crack opening displacement (COD) method. The investigation of the fracture behavior of the two materials includes the effect of the specimen thickness as well as specimen configuration. The experimental tests were carried on the compact tension (CT) specimens and the single edge notch bending (SENB) specimens. At −70°C, the materials show elastic behavior, the ASTM test method for determining fracture toughness is applied to SENB specimens to determine KIC of both materials. PE80 shows greater resistance to fracture than PE100.

The Fracture Toughness of Hardened Tool Steels

1987 ◽  
Vol 109 (4) ◽  
pp. 314-318 ◽  
Author(s):  
D. F. Watt ◽  
Pamela Nadin ◽  
S. B. Biner
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Slow Crack Growth ◽  
Crack Opening ◽  
Compact Tension ◽  
Testing Procedure ◽  
Tool Steels ◽  
Opening Displacement ◽  
Tempering Temperature ◽  
Toughness Testing

This report details the development of a three-stage fracture toughness testing procedure used to study the effect of tempering temperature on toughness in 01 tool steel. Modified compact tension specimens were used in which the fatigue precracking stage in the ASTM E-399 Procedure was replaced by stable precracking, followed by a slow crack growth. The specimen geometry has been designed to provide a region where slow crack growth can be achieved in brittle materials. Three parameters, load, crack opening displacement, and time have been monitored during the testing procedure and a combination of heat tinting and a compliance equation have been used to identify the position of the crack front. Significant KIC results have been obtained using a modified ASTM fracture toughness equation. An inverse relationship between KIC and hardness has been measured.

Influence of Sulfur Content on the Fracture Toughness Properties of 2 1/4 Percent Cr-1 Percent Mo Steel

1976 ◽  
Vol 98 (2) ◽  
pp. 135-142 ◽  
Author(s):  
J. F. Copeland
Keyword(s):  
Fracture Toughness ◽  
Sulfur Content ◽  
Detrimental Effect ◽  
Crack Opening ◽  
Analytical Techniques ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Tension Specimen ◽  
Microvoid Coalescence ◽  
Opening Displacement

The effects of sulfur content on the fracture toughness properties of 2 1/4Cr-1 Mo steel were evaluated at test temperatures above, at, and below the nil ductility transition temperature (NDTT) of −23°C (−10°F). Small, 12.7-mm (0.5-in.) thick compact tension specimen results were combined with J-integral, Equivalent Energy, and Crack Opening Displacement analytical techniques to provide KIc results up to 22°C (72°F). It was found that the sulfur content of this steel has a large detrimental effect on KIc at the NDTT and above, where microvoid coalescence is the fracture mode. Sulfur has no significant effect at −73°C (−100°F) where cleavage occurs. These results also indicate that the higher Charpy V-notch energy at NDTT, shown by lower sulfur steels, is translatable into increased fracture resistance.

Compact Tension Testing of Asphalt Binders at Low Temperatures

2017 ◽  
Author(s):  
Michelle Edwards
Keyword(s):  
Fracture Toughness ◽  
Fracture Energy ◽  
Low Temperatures ◽  
Compact Tension ◽  
Small Sample ◽  
Test Method ◽  
Asphalt Binders ◽  
Notch Depth ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement

This presentation will document and discuss the development of a compact tension test for the grading of asphalt binders at low temperatures. The geometry was chosen because it provides an easy way to obtain the plane ­strain fracture toughness, fracture energy, and crack tip opening displacement in brittle failure on a small sample. It is believed that the method will allow for a better ranking of binders in regard to their low ­temperature fracture resistance. Compact tension specimens were prepared in different sizes with varying notch depths. Fracture toughness was found to be constant, regardless of the notch depth or specimen width for both straight and modified binders. Fracture energy was found to decrease with notch depth, which is thought to be the result of energy ­absorbing mechanisms away from the crack­tip. Deeper notches or an energy correction is able to account for that issue. Reproducibility of the fracture test was found to be good with a standard deviation of five to ten percent for fracture toughness and fifteen to twenty percent for fracture energy, which is typical for such tests. Given the fact that brittle fracture properties can vary by orders of magnitude for binders of the same Superpave grade, it is concluded that the test method has a high ability to reveal statistically significant differences in toughness.

Numerical Simulation and Experimental Investigation of Damage Behaviour on Al6061 Laser Welded Joints

2014 ◽  
Vol 627 ◽  
pp. 105-108
Author(s):  
H.Y. Tu ◽  
Siegfried Schmauder ◽  
Ulrich Weber
Keyword(s):  
Numerical Simulation ◽  
Fracture Toughness ◽  
Welded Joints ◽  
Welded Joint ◽  
Volume Fraction ◽  
Crack Opening ◽  
Compact Tension ◽  
Void Volume Fraction ◽  
Opening Displacement ◽  
Hardness Tests

The ductile damage behaviour of an aluminium laser welded joint is studied experimentally and numerically. The dimensions of the weld regions are fixed by hardness tests. Fracture toughness tests of Al6061 laser beam welded joints were performed with the compact tension (C(T)) specimens. The Rousselier model is used and the parameters: initial void volume fraction (f0) and average void distance (lc) are identified by metallographic investigations, for the BM, the FZ and the HAZ. Numerical calibration of the Rousselier parameters is performed on notched round specimens. The same Rousselier parameters are used to predict force vs. Crack Opening Displacement (COD) of C(T) specimens.

A New Methodology for Estimating Fracture Criterion of Thin Sheets

2009 ◽  
Vol 417-418 ◽  
pp. 305-308
Author(s):  
Kalyan Kumar Ray ◽  
Ashmita Patra ◽  
Debashish Bhattacharjee
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Specimen Thickness ◽  
Interstitial Free ◽  
Thin Sheets ◽  
If Steel ◽  
Opening Displacement ◽  
Critical Crack ◽  
Suggested Technique ◽  
Critical Crack Opening

A simple and reliable method has been proposed for determining fracture toughness of thin sheets. The principle of the method considers that critical crack opening displacement (c) corresponds to a specific amount of load drop during fracture toughness tests. The suggested technique yields c value for an interstitial free (IF) steel as 2.04 mm in excellent correspondence with an indirect estimate of 1.97 mm from the popular energy extrapolation technique. The magnitude of c for IF steel sheets is found to decrease with decreasing thickness in agreement with the expected variation of this criterion with specimen thickness in gross yielding fracture mechanics (GYFM) regime.

Applicability of a Deterministic Approach to Predict the Minimum Fracture Toughness in the DBTT Region From Tensile Test Results: Example for 0.5T SE(B) and 1TCT Specimens

2016 ◽  
Author(s):  
Toshiyuki Meshii ◽  
Yusuke Fujita ◽  
Teruhiro Yamaguchi
Keyword(s):  
Fracture Toughness ◽  
Tensile Test ◽  
Size Effects ◽  
Crack Opening ◽  
Crack Tip ◽  
Thickness Effect ◽  
Specimen Thickness ◽  
Test Results ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement

Fracture toughness Jc of the material in ductile to brittle transition temperature region is known to have two specimen size effects; the planar size effect and the test specimen thickness effect. It was presented that these size effects can be solved by applying modified Richie-Knott-Rice failure criterion in previous research. As a next step, in this study, engineering method to predict the minimum Jc for a specimen type and thickness from only tensile test results is proposed. The method focused on our finding the crack-opening stress σ22, measured at a distance from the crack tip equal to four times the crack-tip opening displacement (CTOD) δt, denoted as σ22d, saturated with increasing load, and the J corresponding to the load first reaching this saturated σ22d, denoted as Js, seemed to predict the minimum toughness for a given specimen and material at a specific temperature. The method was validated for 0.5T SE(B) and 1TCT specimen. The material was 0.55% carbon steel JIS 0.55C, which was tested at master curve reference temperature.

Study of Constraint Issues in Elasto-Plastic Fracture Analysis Using Experimental and Finite Element Simulation

2017 ◽  
Author(s):  
Md Ibrahim Kittur ◽  
Krishnaraja G. Kodancha ◽  
C. R. Rajashekar
Keyword(s):  
Finite Element ◽  
Mild Steel ◽  
Compact Tension ◽  
Specimen Thickness ◽  
J Integral ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
3D Fea ◽  
The Comparative Study ◽  
Crack Tip Opening

In this investigation, the variation of J-integral considering Compact Tension (CT) specimen geometry varying a/W and σ using 2D and 3D elasto-plastic Finite Element (FE) analysis have been studied. Further, the investigation has been done to examine the relationship between the J and δ for varied a/W and σ. The plane stress and plane strain elasto-plastic FE analyses have been conducted on the CT specimen with a/W = 0.45–0.65 to extract the J and Crack-tip Opening Displacement (CTOD) values for mild steel. The comparative study of the variation of dn with a/W of mild steel with earlier results of IF steel is carried out. The study clearly infers the effect of yield stress on the variation of the magnitude of dn with reference to a/W ratio. The present analysis infers that while converting the magnitude of the CTOD to J one needs to carefully evaluate the value of dn depending on the material rather than considering it to be unity. Further, the study was extended to experimental and 3D FEA wherein J-integral and CTOD were estimated using the CT specimen. Experimental results reveal that the crack length, the specimen thickness, and the loading configuration have an effect on the fracture toughness measurements. The error analysis between the results obtained by 3D FEA and experimentation were conducted and found to be within limits.

Using Torsion Bar Testing to Determine Fracture Toughness of Ceramic Materials

2002 ◽  
Author(s):  
J. A. Wang ◽  
K. C. Liu ◽  
G. A. Joshi
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Torsion Test ◽  
Ceramic Materials ◽  
Type Specimen ◽  
Small Region ◽  
Fracture Load ◽  
Test Method ◽  
Finite Element Program ◽  
Spiral Line

A new method, designated as Spiral Notch Torsion Test (SNoTT), is introduced for determining fracture toughness KIC of materials ranging from metallic alloys to brittle ceramics and their composites. A round-rod specimen having a V-grooved spiral line with a 45° pitch is subjected to pure torsion. This loading configuration creates a uniform tensile-stress crack-opening mode, Mode-I, with a transverse plane-strain state along the grooved line. This technique is analogous to the conventional test method using a compact-type specimen with a thickness equivalent to the full length of the spiral line. KIC values are determined from the fracture load and crack length with the aid of an in-house developed 3-D finite element program (TOR3D-KIC). A mixed mode (modes I and III) fracture toughness value can be determined by varying the pitch of the spiral line or varying the ratio of axial to torsion loads. Since the key information needed for determining KIC values is manifested within a small region near the crack tip, the specimen can be significantly miniaturized without the loss of generality. Limited results obtained for various materials are compared with published KIC values, showing differences of less than 2% in general and 6% maximum in one case. The experimental technique and theoretical basis of the proposed method are presented in detail.

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