Chevron-Notched Specimens for Measuring Adhesive Fracture Toughness

2009 ◽  
pp. 69-69-14 ◽  
Author(s):  
J Spingarn
Keyword(s):  
Fracture Toughness ◽  
Adhesive Fracture ◽  
Notched Specimens

Fracture Toughness and Cracking Behaviour of SCC Compared to VC

2013 ◽  
Vol 577-578 ◽  
pp. 205-208
Author(s):  
Sara Korte ◽  
Veerle Boel ◽  
Wouter de Corte ◽  
Geert de Schutter
Keyword(s):  
Fracture Toughness ◽  
Fracture Process ◽  
Critical Value ◽  
Fracture Parameter ◽  
Self Compacting Concrete ◽  
Bending Tests ◽  
Three Point Bending ◽  
Notched Specimens ◽  
Subsequent Determination

Vibrated concrete (VC) and self-compacting concrete (SCC) have a substantially different composition, resulting in dissimilar mechanical properties regarding cracking behaviour. The critical value of the mode I stress-intensity factor KICis an appropriate fracture parameter for evaluating fracture toughness and can be obtained from three-point bending tests (3PBT) on small, notched specimens. Subsequent determination of the energy release rate thus allows to examine the crack propagation and fracture process of both concrete types. This paper describes the results of such 3PBTs on samples, made from VC and SCC. Evaluation of the cracking behaviour, derived from these results, reveals remarkable differences.

Fracture Toughness Characterization of Carbon Bonded Alumina Using Chevron Notched Specimens

2017 ◽  
Vol 754 ◽  
pp. 71-74 ◽  
Author(s):  
H. Zielke ◽  
Martin Abendroth ◽  
Meinhard Kuna
Keyword(s):  
Fracture Toughness ◽  
Ceramic Material ◽  
Bending Test ◽  
Parameter Study ◽  
Zone Model ◽  
Displacement Curve ◽  
Notched Specimens ◽  
Load Displacement ◽  
Set Up

A new generation of multifunctional filters is made of carbon bonded alumina and is investigated within the collaborative research center 920 (CRC920). These filters are used during a casting process with the aim of reducing non-metallic inclusions in the cast product. The high thermal and mechanical loading of the filter requires a fracture mechanical characterization of the investigated ceramic material. In order to determine the fracture toughness of the ceramic material, a chevron-notched beam method (CNB) is applied. A 4-point-bending test set-up was constructed and brought into service, at which the load-displacement curve of small chevron-notched specimens (5 x 6 x 25 mm3) can be measured. The set-up offers the possibility of testing specimens at temperatures up to 1000oC. Preceding numerically work using the finite element method was performed to identify a suitable notch geometry. For this purpose a cohesive zone model was used. A parameter study is presented, which shows the influence of the notch parameter on the load-displacement curve.

Notch Effects on Room Temperature Tensile and Bend Properties of Ni3Al and Ni3Al+B

1988 ◽  
Vol 133 ◽  
Author(s):  
P. S. Khadkikar ◽  
J. D. Rigney ◽  
J. J. Lewandowski ◽  
K. Vedula
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Stress ◽  
Room Temperature ◽  
Tensile Tests ◽  
Boron Addition ◽  
Notched Specimens ◽  
Grain Boundary Fracture ◽  
Bend Tests ◽  
Boundary Fracture

ABSTRACTThe notched mechanical properties of Ni3AI and Ni3Al+B prepared by powder metallurgy techniques have been determined in both tension and bending at room temperature. Ten- sile tests performed using double notched specimens containing relatively blunt notches produced intergranular fracture in both Ni3Al and Ni3AI+B, with evidence of fracture initiating in an intergranular manner ahead of the blunt notch in both cases. Estimates of notched fracture toughness from bend tests and of local grain boundary fracture stress from the notched tensile tests suggest an increase in these values with boron addition.

Effect of Crystallographic Orientation on The Fracture Toughness of NiAl Single Crystals

1994 ◽  
Vol 364 ◽  
Author(s):  
S. Shrivastava ◽  
F. Ebrahimi
Keyword(s):  
Fracture Toughness ◽  
Single Crystals ◽  
Heat Treating ◽  
Sem Analysis ◽  
Internal Stresses ◽  
Electric Discharge Machine ◽  
Notched Specimens ◽  
Heat Treated ◽  
Before And After ◽  
Discharge Machine

AbstractIn the present study, single-edge notched bend specimens of NiAl single crystals were tested in {100}<010>, {101}<101=, and {101}<010} orientations before and after heat-treating the notched specimens at 1000°C for one hour. The fracture toughness data for the non heat-treated specimens were found to be consistent with the previous results. An increase in the fracture toughness of NiAl was observed in all orientations studied upon heat-treating the notched specimens. The toughness ratio for the two orientations obtained from the heat-treated notched specimens was found to be 1.2. This ratio is in agreement with the reported stress analysis considering the crack kinking in {100} oriented specimens. A detailed SEM analysis revealed that the electric discharge machine (EDM) cutting of the notch caused the formation of sharp microcracks at the notch front and also created internal stresses in the vicinity of the notch. The increase in toughness upon heat treatment is attributed to the modification of EDM damage.

scholarly journals Fracture toughness of ice and firn determined from the modified ring test

1995 ◽  
Vol 41 (138) ◽  
pp. 383-394 ◽  
Author(s):  
Mark P. Fischer ◽  
Richard B. Alley ◽  
Terry Engelder
Keyword(s):  
Fracture Toughness ◽  
Loading Rate ◽  
Greenland Ice Sheet ◽  
Average Density ◽  
Ring Test ◽  
Ring Specimen ◽  
Near Surface ◽  
Water Ice ◽  
Notched Specimens ◽  
Vertical Variations

AbstractThe modified ring test is used to determine the fracture toughness of synthetic, granular, fresh-water ice average density 0.891 Mg m−3and firn (average density 0.605 Mg m3) from depths between 26 and 27.2 m in the E core of the Greenland Ice Sheet Project II. Average fracture toughness is 145.7kPa m2for the manufactured ice and 108.6kPam½for the firn. Comparison between the ice and firn suggests that ice-fracture toughness decreases with decreasing density (i.e. increasing porosity), suggesting lateral and vertical variations in the near-surface fracture resistance of glaciers and ice sheets may be related to firn densification. The modified ring test has many advantages over conventional, notch-based specimens in that complications which arise in notched specimens due to crack-length, loading-rate, notch-acuity and specimen-size effects are irrelevant for a modified ring-specimen geometry.

Rate effects on the estimation of fracture toughness by small punch tests in hydrogen embrittlement

2019 ◽  
Vol 54 (7-8) ◽  
pp. 390-400 ◽  
Author(s):  
Borja Arroyo ◽  
Jose Alberto Álvarez ◽  
Federico Gutiérrez-Solana ◽  
Roberto Lacalle ◽  
Pablo González
Keyword(s):  
Fracture Toughness ◽  
Hydrogen Embrittlement ◽  
Slow Rate ◽  
Environment Interaction ◽  
Small Punch Test ◽  
Small Punch ◽  
Notched Specimens ◽  
Punch Test ◽  
Material Environment ◽  
Rate Effects

In this article, different techniques to test notched small punch test samples in fracture conditions in aggressive environments are studied, based on the comparison of the micromechanisms at different rates. Pre-embrittled samples subsequently tested in air at rates conventionally employed (0.01 and 0.002 mm/s) are compared to embrittled ones tested in environment at the same rates (0.01 and 0.002 mm/s) and at a very slow rate (5E–5 mm/s). A set of samples tested in environment under a set of constant loads that produce very slow rates completes the experimental results. As a conclusion, it is recommended to test small punch test notched specimens in environment at very slow rates, of around E–6 mm/s, when characterizing in hydrogen embrittlement scenarios, in order to allow the material–environment interaction to govern the process.

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