Improved Elastic Compliance Equation and its Inverse Solution for Compact Tension Specimens

2017 ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Crack Length ◽  
Maximum Error ◽  
Compact Tension ◽  
Crack Size ◽  
Accurate Solution ◽  
Elastic Compliance ◽  
Load Line Displacement ◽  
Standard Specimens ◽  
Specimen Test ◽  
Toughness Testing

ASTM E1820 is a well-developed fracture test standard and has been used worldwide for fracture toughness testing on ductile materials in terms of the J-integral or J-R curve. This standard recommends the elastic unloading compliance technique for measuring crack length in a single specimen test, and an accurate elastic compliance equation is needed to estimate physical crack length. Compact tension (CT) specimen is one of the most often used standard specimens with crack length ratios of 0.45≤a/W≤0.70 prescribed in E1820 for J-R curve testing. The stress intensity factor K of CT specimens used in E1820 was developed by Srawley (IJF, 1976) and has been commonly accepted as the most accurate solution. The compliance equation of CT specimens was developed by Saxena and Hudak (IJF, 1978) and has been used in ASTM E1820 for decades. However, recent results showed that the load-line displacement (LLD) compliance equation is not consistent with that determined from its K solution, and the maximum error of LLD compliance can be larger than 7% at a/W = 0.32 and ∼ 5% at a/W = 0.45 (E1820 standard crack size). The FEA results confirmed that the K solution in E1820 is indeed very accurate, but its compliance equation is less accurate. Thus, an improved compliance equation with high accuracy is developed from the accurate K solution using the numerical integration technique and shooting method.

Determination of Eurofer97 Fracture Toughness by Testing Small C(T) Specimens

2021 ◽  
Author(s):  
David Andres ◽  
Marta Serrano ◽  
Rebeca Hernandez ◽  
Yiqiang Wang ◽  
Mark Richardson
Keyword(s):  
Fracture Toughness ◽  
Compact Tension ◽  
Main Concern ◽  
Martensitic Steels ◽  
Term Operation ◽  
Standard Specimens ◽  
Specimen Test ◽  
Water Reactors ◽  
The One

Abstract The use of small specimen test techniques (SSTT) to determine the mechanical properties of irradiated materials has been studied over the past decades both in fission and fusion programs, but also to characterise and optimise new materials by nuclear and non-nuclear communities. Currently a number of activities are running that focus on the standardisation of SSTT to determine fracture toughness properties for fusion reactor materials (IAEA [1], EUROfusion [2], F4E [3]), and to support the long-term operation of light-water reactors (CRIEPI [4]). The determination of the T0 reference temperature (ASTM E1921 [5]) has been successfully achieved by testing small compact tension (C(T)) specimens (W = 8mm, B = 4mm) of non-irradiated and irradiated pressure vessel materials. However, some concerns exist regarding the use of the Master Curve (MC) on ferritic-martensitic steels, not only with SSTT but also with standard specimens. The main concern is the slope of the MC [6, 7], that seems to be steeper than the standard one. In this paper, the fracture toughness of Eurofer97 has been obtained by testing small C(T) specimens with the geometry selected in IFMIF-DONES (W = 9.2mm, B = 4.6mm) in the transition region. T0 has been determined and compared to the one obtained from 0.5T-C(T) specimens (both normalised to 1T). The scatter of the results has also been assessed to validate the scatter description of the MC.

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.

Fracture Toughness Behaviour of 316L Stainless Steel Samples Manufactured Through Selective Laser Melting

2018 ◽  
Author(s):  
Catrin M. Davies ◽  
Ruijan Zhou ◽  
Olivia Withnell ◽  
Richard Williams ◽  
Tobias Ronneberg ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Selective Laser Melting ◽  
316L Stainless Steel ◽  
Compact Tension ◽  
Crack Plane ◽  
Laser Melting ◽  
Growth Plane ◽  
Toughness Testing ◽  
Tension Fracture

Selective laser melting (SLM) is a relatively new manufacturing technique which offers many benefits. However the utilisation of SLM manufactured components depends on the assurance of their integrity during operation. Fracture toughness testing (JIC) has been performed on as-built compact tension fracture mechanics samples manufactured in three orthogonal directions. When the crack growth plane was transverse to the interface of the build layers, the fracture toughness values were found to be similar to those manufactured using conventional techniques. However, the fracture toughness is significantly reduced when the crack plane is parallel to the interface of the build layers. Simple heat treatments have been performed on Charpy fracture samples and the resulting impact energy values indicate that the fracture toughness of a component may be improved by heat treatment.

Single Edge Precrack V-Notched Beam (SEPVNB) Fracture Toughness Testing on Silicon Nitride

2019 ◽  
Vol 962 ◽  
pp. 205-209
Author(s):  
Tjokorda Gde Tirta Nindhia ◽  
Tanja Lube
Keyword(s):  
Fracture Toughness ◽  
Silicon Nitride ◽  
Crack Size ◽  
Fracture Toughness Test ◽  
Single Edge ◽  
Razor Blade ◽  
Sintered Ceramic ◽  
Toughness Test ◽  
Toughness Testing ◽  
Diamond Paste

The previous Measurement of fracture toughness test by using bright indentation for precracked beam method (ASTM C1421) was found difficult to be carried out due to difficulty in precrack generation and measurement of the crack size. In this research single edge precrack V-notch beam (SEPVNB) is introduced as an alternative to solve the problem from previous standardized method. A real crack that can created with referred size is recognized as the best condition for fracture toughness test. The material prepared for this purpose was silicon nitride (Si3N4) produced by CeramTec (Plochingen, Germany) under the name SL200 B. It is a gas pressure sintered ceramic containing 3 wt.% Al2O3 and 3 wt.% Y2O3. The V Notch was prepared by using razor blade with diamond paste following ISO/FDIS 23146 standard preparation with more addition on precrack introduction. The precrack was introduced by so called opposite roller loading. The fracture toughness test was carried out by following procedure in ISO/FDIS 23146 . The result then was compared for validation with both single edge V-notch beam standard (ISO/FDIS 23146 ) and Surface crack in Flexure SCF (ASTM C 1421). The result of fracture toughness by using method that is introduce in this research is found 5.8270.275 MPa1/2 which is close to the result of SCF (5.335 0.222 MPa1/2). Meanwhile the value of fracture toughness by using V-notch beam is 4.9130.098 MPa1/2

Effects of Overload on Fatigue Strength of SUS316 Having a Crack-Like Surface Defect

2010 ◽  
Author(s):  
Hiroko Oosedo ◽  
Koji Takahashi ◽  
Kotoji Ando
Keyword(s):  
Fatigue Strength ◽  
Fatigue Test ◽  
Surface Defect ◽  
Compact Tension ◽  
Crack Size ◽  
Fatigue Tests ◽  
Stress Intensity Factor Range ◽  
Bending Fatigue ◽  
Bending Fatigue Test ◽  
Key Factor

The effects of overload on the fatigue strength and threshold stress intensity factor range (ΔKth) in SUS316 were studied. Tensile overload was applied to compact tension (CT) specimens with a large crack and fatigue tests were carried out to determine the ΔKth. Tensile or compressive overload was applied to bending fatigue test specimens with a small crack-like surface defect and fatigue tests were carried out to determine the fatigue limit and ΔKth. It was found that the ΔKth increased by tensile overloading. The increasing rate of ΔKth in the CT specimen is larger than that in the bending fatigue test specimen. Thus, the crack size effects on the improvement of ΔKth after overloading were observed. The results are discussed from the viewpoint of fracture mechanics. The size of compressive residual stress is the key factor of the increasing rate.

Rationalizing spacing requirements for nailed wood connections by induced wood splitting

1992 ◽  
Vol 19 (5) ◽  
pp. 842-846
Author(s):  
Peter W. C. Lau
Keyword(s):  
Moisture Content ◽  
Crack Length ◽  
Digital Imaging ◽  
Critical Stress ◽  
Imaging Techniques ◽  
Crack Size ◽  
Parallel Study ◽  
Dimension Lumber ◽  
Different Types ◽  
Nail Diameter

Nails of five different types and sizes were driven through test specimens cut from 35 × 85 mm Douglas-fir and eastern spruce (spruce-pine-fir) dimension lumber, preconditioned to 12% moisture content. Each specimen received either a single nail or two identical nails, spaced at 10 times the nail diameter for common and spiral nails, or at 25 mm for glulam rivets. Nail-induced crack size was evaluated using digital imaging techniques. These crack data were analysed together with the data on single-nail specimens obtained in a parallel study. This permitted the development of a model predicting mean crack length on the basis of spacing between nails. This model was used to generate the spacing requirements based on a criterion on critical stress for fracture, and on crack length. Key words: nailing, wood connections, cracking, nail spacing.

Detection of Multiple Cracks in Triangular Cantilevers Based on Frequency Measurements

2006 ◽  
Vol 324-325 ◽  
pp. 259-262
Author(s):  
Fei Wang ◽  
Xue Zeng Zhao ◽  
Jia Ying Chen
Keyword(s):  
Damage Index ◽  
Maximum Error ◽  
Crack Size ◽  
Force Sensors ◽  
Multiple Cracks ◽  
Cantilever Deflection ◽  
Local Flexibility ◽  
Small Force ◽  
The Relationship ◽  
Number Of Segments

Triangular cantilevers are used as small force sensors. Prediction of location and size of multiple cracks from experimental results will be of value to users and designers of cantilever deflection force sensors. We extend a method for prediction of location and size of multiple cracks in rectangular cantilevers to deal with triangular cantilevers in this paper. The cracks are assumed to introduce local flexibility change and are modeled as rotational springs. The beam is divided into a number of segments, and each segment is associated with a damage index, which can be calculated through the relationship between the damage index and strain energy of each segment and the changes in the frequencies caused by the cracks. The location of cracks can be obtained with high accuracy with sufficient segment numbers. The size of a crack can be calculated through the relationship between the crack size and its stiffness, which can be obtained from the damage index related to the crack. The maximum error in prediction of the crack position in the case of double cracks is less than 15%, and it is less than 25% in prediction of the crack size.

Determination of the Fracture Toughness Parameters for an MDF Cement Composite

1985 ◽  
Vol 64 ◽  
Author(s):  
M. Arzamendi ◽  
R. L. Sierakowski ◽  
W. E. Wolfe
Keyword(s):  
Fracture Toughness ◽  
Cement Composite ◽  
Compact Tension ◽  
Test Methods ◽  
Standard Test ◽  
Elastic Behavior ◽  
Hardened Cement ◽  
Linear Elastic ◽  
Toughness Testing

ABSTRACTThe experimental results of fracture toughness testing of a Macro Defect (MDF) Free cement are presented. The material, a hydraulic cement with hydrolyzed polyvinyl polymers, behaves much like a hardened ceramic with measured maximum compressive and tensile strengths of 380 MN/m2 and 69 MN/m2 respectively. Fracture toughness tests were performed on compact tension (CT) and single edge notched beam (SENB) specimens cut from test panels which were supplied in 3mm, 5mm and 10mm thicknesses. The results were evaluated with respect to the fracture toughness parameter Kic using a modification of standard test methods as determined by observed natural behavior. The MDF material exhibited an essentially linear elastic behavior with a fracture toughness slightly higher than typical values recorded for hardened cement paste.

Prediction of Fatigue Crack Growth of 2024-T351 by Grey GM(1,1) Model with Rolling Check

2013 ◽  
Vol 690-693 ◽  
pp. 1779-1783 ◽  
Author(s):  
Chih Chung Ni
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Length ◽  
Crack Growth ◽  
Compact Tension ◽  
Growth Data ◽  
Alloy Plate ◽  
Loading Cycle ◽  
Crack Growth Curve ◽  
Accuracy Of Prediction

The study is focused on the investigations into applying the grey model with rolling check to the prediction of fatigue crack growth. Fatigue crack growth data of compact tension specimens made of 2024-T351 aluminum-alloy plate tested under constant-amplitude loads were carried out for verifications. The optimal values of parameter affecting the accuracy of prediction were found by variational analysis. Using four experimental crack lengths as the source series and the optimal value of parameter for modelling with rolling check, it was found almost entire fatigue crack growth curve of the specimen can be predicted accurately. Besides, the analyzed results including number of rolling check performed, loading cycle corresponding to the maximum predicted crack length, fractured cycle of specimen, cycle ratio of loading cycle and fractured cycle, and percentage of error between maximum predicted and experimental crack length for all specimens were tabulated.

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