scholarly journals Evaluation of linear-elastic fracture toughness of the teeth restored with different post and core systems

2015 ◽  
Vol 7 (8) ◽  
pp. 125-129
Author(s):  
Lamartine De Moraes Melo Neto Clovis ◽  
Afonso Franciscone Paulo ◽  
Mondelli Jose ◽  
Sbeghen Sabio Silvia ◽  
Lorenzi Poluha Rodrigo ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Post And Core

Validation of Linear Elastic Fracture Mechanics in Predicting the Fracture Toughness of Polyethylene Pipe Materials

2015 ◽  
Author(s):  
Tarek M. A. A. El-Bagory ◽  
Hossam E. M. Sallam ◽  
Maher Y. A. Younan
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Linear Elastic Fracture Mechanics ◽  
Operating Conditions ◽  
Specimen Thickness ◽  
Crosshead Speed ◽  
Linear Elastic ◽  
Piping Systems ◽  
Elastic Fracture ◽  
Point Bend

The main purpose of the present paper is to compare between the fracture toughness based on linear elastic fracture mechanics (GIC), and that based on nonlinear fracture mechanics (JIC). The material of the investigated pipe is a high-density polyethylene (HDPE), which is commonly used in natural gas piping systems. The welds at the pipe junction are produced by butt-fusion (BF), welding. Curved three-point bend (CTPB), fracture specimens are used. The crosshead speed ranged from 5 to 500 mm/min and specimen thickness ranged from 9 to 45mm for both welded and unwelded specimens at room temperature Ta, equal 23°C. The study reveals that the crosshead speed has a significant effect on the fracture toughness of both welded and unwelded specimens. The results of GIC for different specimen thickness and crosshead speed found previously by the authors [1] have been compared with JIC under the same operating conditions [2]. The comparison between welded and unwelded specimens revealed that in the welded specimens there is a marginal difference between fracture toughness measured using linear elastic fracture mechanics LEFM and elastic plastic fracture mechanics EPFM, for both crosshead speeds.

Mechanical Modal and Numerical Simulation of Fracture Process of Block Wall

2011 ◽  
Vol 217-218 ◽  
pp. 1438-1443
Author(s):  
Yan Li ◽  
Xin Sheng Yin ◽  
Bo Wang
Keyword(s):  
Numerical Simulation ◽  
Fracture Toughness ◽  
Fracture Process ◽  
Concrete Block ◽  
Critical Value ◽  
Specimen Size ◽  
Linear Elastic ◽  
Block Wall ◽  
Elastic Fracture ◽  
Aerated Concrete

Aerated concrete is a typical non-uniform quasi-brittle materials, the fracture process is very complicated. To slove the problem of cracks in this block walls, a practical analytical method was proposed based on the vertical mortar joint model to solve the equivalent fracture toughness (the critical value which the crack occurred to spread unstable) With the use of the basic principle of composite material mechanics and linear elastic fracture mechanics. Against the results of the related experiments, the standard deviation and the coefficient of variation of Analytical Solution are smaller, , and the equivalent fracture toughness is the effective fracture parameters of independent of specimen size. So the suggested method is more feasible and applicable, which can forecast autoclaved aerated concrete block wall’s cracking and destroying.

Fracture Toughness Study on Zr-based Bulk Metallic Glasses

2007 ◽  
Vol 1048 ◽  
Author(s):  
Jin-yoo Suh ◽  
Mary Laura Lind ◽  
C. Paul Kim ◽  
R. Dale Conner ◽  
William L Johnson
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Metallic Glasses ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Fracture Surfaces ◽  
Linear Elastic ◽  
Elastic Fracture

AbstractThe fracture toughness of Zr-based bulk metallic glasses of various compositions was studied in the as-cast and annealed condition. Properties were characterized using x-ray and differential scanning calorimetry (DSC) and fracture surfaces were examined using electron microscopy (SEM). Quaternary Zr-Ti-Cu-Be alloys consistently had linear elastic fracture toughness values greater than 80 MPa·m1/2, while Vitreloy 1, a Zr-Ti-Cu-Ni-Be alloy, had an average fracture toughness of 48.5 MPa·m1/2 with a large amount of scatter. The addition of iron to Vitreloy 1 reduced the fracture toughness to 25 MPa·m1/2. Fracture surfaces were carefully analyzed using electron microscopy. Some samples had highly jagged patterns at the beginning stage of crack propagation, and the roughness of this jagged pattern correlated well with the measured fracture toughness values. These jagged patterns, the main source of energy dissipation in the sample, were attributed to the formation of shear bands inside the sample. The Zr-Ti-Cu-Be alloy, having KQ=85 MPa·m1/2 as cast, was annealed at various time/temperature combinations. When the alloy was annealed 50°C below Tg, the fracture toughness dropped to 6 MPa·m1/2, while DSC and X-ray showed the alloy to still be amorphous. The roughness of the fracture surfaces on relaxed samples also compared well with the relative fracture toughness.

scholarly journals Void Content and its Influence on the Fracture Behaviour of Long Fibre Reinforced Injection Molded Polypropylene

2004 ◽  
Vol 13 (6) ◽  
pp. 096369350401300
Author(s):  
Victor Iliev Rizov
Keyword(s):  
Fracture Toughness ◽  
Testing Machine ◽  
Compact Tension ◽  
Void Content ◽  
Linear Elastic ◽  
Static Testing ◽  
Glass Fibre Reinforced ◽  
Injection Molded ◽  
Elastic Fracture ◽  
Static Testing Machine

The influence of void content on the fracture performance of discontinuous long glass fibre reinforced injection molded polypropylene was studied. Compact tension specimens were machined from simple plate-tools and were loaded in a static testing machine in a laboratory environment. From the resulting load-displacement curves the fracture toughness was determined on the basis of the linear elastic fracture mechanics. It was found that higher void content causes a decrease in the fracture toughness.

A Measure for the Fracture Toughness of Cement Based Materials

1984 ◽  
Vol 42 ◽  
Author(s):  
Y. S. Jenq ◽  
S. P. Shah
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Direct Method ◽  
Maximum Load ◽  
Nonlinear Finite Element ◽  
Linear Elastic ◽  
Cement Based Materials ◽  
Notch Length ◽  
Elastic Fracture ◽  
A Direct Method

It is frequently reported that the higher the strength of cement based materials, the more brittle is their behavior. It could he useful to quantitatively express the degree of brittleness. Many attempts [1–13] have been made to use linear elastic fracture mechanis (LEFM) to quantitatively express the degree of brittleness. For example, by testing notched beams one can calculate, using the formulas developed from LEFM, a quantity called fracture toughness and termed KIC from the measured maximum load and the initial notch-length. Unfortunalely, it has been observed that K thus calculated is dependent on the dimension of the beams. Many researchers have attempted to analyze this size dependency. Such approaches are usually quite cumbersome and are often based on expensive nonlinear finite element programs. In this paper a direct method is suggested to calculate two size-independent fracture toughness parameters from the experimental results. The method was developed based on tests on notched-beams of different mix proportions and different sizes.

Fracture Toughness and Quantitative Computed Tomography Number of Human Tibia Cortical Bone

1998 ◽  
Vol 02 (02) ◽  
pp. 151-165
Author(s):  
Gladius Lewis
Keyword(s):  
Computed Tomography ◽  
Fracture Toughness ◽  
Quantitative Computed Tomography ◽  
Compact Bone ◽  
Positive Influence ◽  
Ct Number ◽  
Linear Elastic ◽  
Key Variables ◽  
Elastic Fracture ◽  
Point Bend

In spite of its importance, the fracture toughness of human bone has been the subject of only a few studies. The objective of the first part of the present work was, thus, to expand this database. For this purpose, linear elastic fracture mechanics (LEFM) principles and single-edge-notched three-point bend specimens were used to determine the fracture toughness of compact bone cut from the tibiae of embalmed cadavers (donor ages between 36 and 94 years). The overall mean and standard deviations of the fracture toughness were 3.12 and 1.21 MP/m, respectively. The case for using LEFM principles, various aspects of four key variables, and the present results are all fully discussed. In the second part of the study, the computed tomography (CT) number of all the specimens were measured. Correlational analysis of all the results demonstrated that CT number exerts a moderately positive influence on fracture toughness for this bone. The clinical significance of this finding is discussed.

Study of Aggregate Size Effect on Fracture Toughness of Petreous Macrocomposites (Concrete)

2010 ◽  
Vol 636-637 ◽  
pp. 1342-1348 ◽  
Author(s):  
Ana S. Marques ◽  
Pedro M. Amaral ◽  
Luís Guerra Rosa ◽  
Jorge Cruz Fernandes
Keyword(s):  
Fracture Toughness ◽  
Particle Size ◽  
Aggregate Size ◽  
Ceramic Materials ◽  
Bending Test ◽  
Aggregate Particle ◽  
Linear Elastic ◽  
Rock Aggregate ◽  
Elastic Fracture ◽  
Fractographic Examination

The present study investigates the effect of rock aggregate size on the fracture toughness of a petreous macrocomposite material (concrete). The effect of aggregate size on the fracture properties of concrete was studied by analysing the fracture toughness KIC results obtained using single edge notched beam (SENB) specimens submitted to 4-point bending test. The results were obtained according to the methodology proposed by Srawley and Gross for monolithic ceramic materials. Additionally, the effect of aggregate size has been analysed by performing fractographic examination of unnotched beam specimens also submitted to 4-point bending test. KIc values obtained via linear elastic fracture mechanics (LEFM) theory applied to the fractographic data were comparable to those obtained by SENB method. The obtained results show that the fracture toughness of concrete depends on the aggregate particle size, although KIC is not linearly related with the particle size. Fracture behaviour depends on the interaction between the used mortar (a mixture of portland cement with sand and water) and the different rock (aggregate) particle sizes. This kind of studies allows further extending the knowledge on the failure mechanisms of concrete, which permits to improve the characteristics of these macrocomposite materials by understanding the effects related to the modification of their structure.

The fracture of wood in tension parallel to the grain

1977 ◽  
Vol 4 (4) ◽  
pp. 412-416 ◽  
Author(s):  
Sidney Mindess
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Physical Interpretation ◽  
Crack Extension ◽  
High Moisture ◽  
Linear Elastic ◽  
Moisture Contents ◽  
Apparent Fracture Toughness ◽  
Elastic Fracture ◽  
Uncracked Ligament

The fracture of commercial Hem-Fir boards in the LR and LT modes was studied, using both saturated and air-dry specimens. Notched samples were tested in flexure (third-point loading). It was found that the concepts of linear elastic fracture mechanics could be applied, even when the crack extension was in a direction perpendicular to the initial notch. However, the physical interpretation of the apparent fracture toughness, [Formula: see text], remains unclear. It was also found that the apparent flexural stsrength increased as the size of the uncracked ligament decreased. Finally, the results indicated that both the nominal flexural strength and the fracture toughness were greater for the saturated specimens, probably due to an increase in viscoelastic behaviour at high moisture contents.

Sign in / Sign up

Export Citation Format

Share Document